CN101656484B - Three-pin package constant current and voltage controller in critical conduction mode - Google Patents

Abstract

The invention discloses a kind of three-pin package constant current and voltage controller in critical conduction mode, there is less external component and can work in critical conduction mode, and still accurately control constant output current and voltage, can be used for realizing self-oscillation flyback converter.This constant current and voltage controller includes: switch control terminal, it is couple to inductor switch, described inductor switch is disconnected by the inductor switch controls signal with turn-on time, it is contained in the controller IC in described integrated antenna package and in constant current mode, adjusts described turn-on time so that the output constant current hold of flyback converter, and in constant voltage mode, adjust described turn-on time so that the output voltage of described flyback converter keeps constant；Feedback terminal, described controller IC receives electric power by described feedback terminal；And ground terminal, described controller IC passes through described ground terminal ground.

Description

Three-pin package constant current and voltage controller in critical conduction mode

Technical field

The present invention relates to Power convert field, a kind of controller in primary side regulation, it only uses three pins Produce constant output current and constant output voltage.

Background technology

Flyback converter is used as battery charger and AC adapter, can provide constant current and to light negative to heavy duty Carry (such as when battery is fully charged) and constant voltage is provided.Flyback converter can be with discontinuous conduction mode (DCM), critical conduction Pattern (CRM) or continuous conduction mode (CCM) work.In discontinuous conduction mode, it is being delivered to all energy of secondary inductor Measure after the most discharging, electric current is started again at before being ramped up by primary inductor, once-existing gap.Leading continuously In logical pattern, electric current stopped running through secondary inductor with release before transmission energy, electric current starts at primary inductor In ramp up.In critical conduction mode, about while electric current stops running through secondary inductor, electric current starts in primary Inducer ramps up.

Flyback converter works in critical conduction mode and has multiple advantage.Such as, work in critical conduction mode The self-oscillation ability of flyback converter can reduce switching loss.Additionally, for obtaining the peak electricity needed for given charge power Sensor electric current is lower than in discontinuous conduction mode in critical conduction mode.Although the average current in both situations is identical, But in critical conduction mode, there is no Dead Time (dead time).Higher energy can be realized when peak point current is relatively low Transmission efficiency.Additionally, higher efficiency can be realized in critical conduction mode than in continuous conduction mode, because leading continuously In logical pattern, just start to charge up at all energy primary inductor before secondary inductor discharges.

Self-oscillation and the flyback converter worked in critical conduction mode have multiple existing design.Fig. 1 (existing skill Art) the prior art self-oscillation flyback converter 10 of graphic extension exemplary, also referred to as " ringing choke converter (ringing choke converter)”.Self-oscillation is to utilize two bipolar transistors to realize.The first transistor Q111 is used as primary inductance The switch of device 12.Transistor seconds Q2 13 turns off the first transistor Q1 11 at the end of each switch cycles.Transducer 10 leads to Transmission from one meridian to another photo-coupler 15 receives feedback from the primary side of transformator 14 and controls its output electric current and voltage.Transducer 10 also utilizes Parallel reference U1 16 in primary side.Such as, parallel reference U1 16 is that its 3rd terminal is adjusted to three pins of 1.25 volts Formula parts TL431.

The shortcoming of transducer 10 is, owing to it uses many parts to perform constant output voltage and constant output current control System, thus it is costly.As it is shown in figure 1, parallel reference U1 16, resistance R2, R3 and R6 and capacitor C2 are for constant defeated Go out Control of Voltage.Transistor Q3 and resistance R4 and R5 controls for constant output current.Also need to photo-coupler 15, controlling Signal processed is delivered to primary side from the primary side of flyback converter 10.The outside bipolar transistor 11 and 13 of in primary side two And photo-coupler 15 and parallel reference 16 all can increase the cost of transducer 10.Additionally, the discrete parts of transducer 10 along with The passage of time is reliable not as the equivalent parts in integrated circuit.

When first transducer 10 is connected, the electric current flowing through startup resistance RSTART 17 makes the base stage electricity of transistor Q1 11 Pressure VB raises and makes transistor Q1 11 turn on.When transistor Q1 11 turns on, formed in secondary inductor 18 positive again Raw feedback, this feds back through R/C network 19 and is applied to the base stage of transistor Q1 11, so that transistor Q1 11 fast conducting. Along with the emitter current of transistor Q1 11 increases, the voltage at emitter resistance RE 20 two ends increases the feedback from photo-coupler 15 Voltage VFB, and raise the base voltage of transistor Q2 13.When transistor Q2 13 turns on, electric current is from transistor Q1's 11 Base stage is released, and base voltage VB reduces.When transistor Q1 11 begins to turn off, electric current stops running through primary inductor 12, And the voltage at all inducer two ends of transformator 14 all inverts according to common inverse-excitation type action.Electric current is by auxiliary Inducer 18 and R/C network 19 flows to the base stage of transistor Q1 11 and regeneration can be caused to turn off.Transistor Q1 11 is held off, directly In transformator 14, all energy of storage are all delivered to primary side.Under heavy load condition, controlled from feedback circuit The switch cycles making next be used for turn on transistor Q1 11 is immediately begun to by the resonance current of auxiliary winding.In light load or empty Under the conditions of load, when electric current is no longer flow through arbitrary inducer, the voltage at inducer two ends drops to zero.When secondary inductor 18 liang The voltage of end is zero and to flow through the input current of starting resistance RSTART 17 again the most long-pending in the base stage of transistor Q1 11 On Ju, transistor Q1 11 is by conducting and starts new circulation.

The embodiment simply too much of Fig. 2 (prior art) display self-oscillation flyback converter 21.Transducer 21 profit Self-oscillation is realized with two bipolar transistors.Received for regulating output electric current and voltage from reflected voltage by transformator 22 Feedback.Although transducer 21 does not use photo-coupler and parallel reference, but the two bipolar transistor and this many discrete parts Increase the cost of transducer.

Being similar to transducer 10, transducer 21 also utilizes Regenerative feedback to make its transistor turns and shutoff.When transducer 21 When first turning on, the electric current flowing through starting resistance RSTART 23 increases the base voltage of transistor Q1 24, and transistor Q1 24 begin to turn on.Transistor Q1 24 fast conducting subsequently, because when it turns on, electric current begins to flow through secondary inductor 25.? Secondary inductor 25 two ends form positive Regenerative feedback voltage, and this feedback voltage is applied to transistor Q1 24 by R/C network 26 Base stage.Along with the increase of the emitter current of transistor Q1 24, the voltage at emitter resistance RE 27 two ends makes transistor seconds Q2 The base voltage of 28 increases.When transistor Q1 24 turns off, the base voltage of transistor seconds Q2 28 is by secondary inductor 25 The feedback voltage at two ends sets, and this feedback voltage is then by by diode D1 and D2, resistance R1 and R2 and capacitor C1 shape The feedback network 29 become regulates.When the voltage at emitter resistance RE 27 two ends increases above by the electricity set by feedback network 29 During pressure, transistor Q1 24 begins to turn off.According to common inverse-excitation type action, when electric current stops running through the primary electrical of transformator 22 During sensor 30, the voltage at all inducer two ends of transformator 22 all inverts.

Now, regeneration is caused because electric current flows to the base stage of transistor Q1 24 by secondary inductor 25 and R/C network 26 Turn off, and make transistor Q1 24 turn off rapidly.Transistor Q1 24 is held off, until be stored in transformator 22 is all Energy is all delivered to primary side.Under heavy load condition, from the resonance current of the secondary inductor 25 that feedback circuit is controlled The switch cycles turning on transistor Q1 24 by making next be used for immediately begins to.Under light load or idle condition, when electric current no longer When flowing through arbitrary inducer, the voltage at inducer two ends drops to zero.When the voltage at secondary inductor 25 two ends is zero and flows The input current crossing starting resistance RSTART 23 gathers the most again in the base stage of transistor Q1 24, and transistor Q1 24 will Turn on and start new circulation.

Including diode D1 and D2, resistance R1 and capacitor C1 feedback network 29 for by turn off transistor Q1 24 To change its ON time to control constant output voltage.Emitter resistance RE 27, resistance R2, capacitor C2 and transistor seconds Q2 28 is used for controlling constant output current.The major defect of flyback converter 21 is output voltage and exports the accurate of electric current Spend poor.

It is an object of the invention to provide a kind of cheap self-oscillation, the flyback converter of primary side controlled, it should have There is less external component and can work in critical conduction mode but still accurately control constant output current and voltage. Such as, trying hard to provide a kind of the flyback converter with the self-oscillation of an external transistor, primary side controlled, it is by holding The controller IC being contained in the IC encapsulation with little pin is controlled.

Summary of the invention

The technical problem to be solved is to provide a kind of critical conduction mode three-pin package constant current voltage Controller, has less external component and can work in critical conduction mode, and still accurately controlling constant output current And voltage, save manufacturing cost.In order to solve above technical problem, the technical scheme is that

First, the invention provides a kind of integrated antenna package, comprising: switch control terminal, be couple to inducer and open Closing, described inductor switch is disconnected by the inductor switch controls signal with turn-on time, is contained in described integrated circuit envelope Controller IC in dress adjusts described turn-on time in constant current mode so that the output electric current of flyback converter is protected Hold constant, and in constant voltage mode, adjust described turn-on time so that the output voltage of described flyback converter keeps perseverance Fixed；Feedback terminal, described controller IC receives electric power by described feedback terminal；And ground terminal, described control Device integrated circuit passes through described ground terminal ground.

Secondly, present invention also offers a kind of integrated antenna package, comprising: switch control terminal, be couple to external electrical Sensor switch and internal power switch, described internal power switch is broken by the inductor switch controls signal with turn-on time Open, and the controller IC being contained in described integrated antenna package adjusts described turn-on time, so that inverse-excitation type turns The output voltage of parallel operation keeps constant；Feedback terminal, is used for receiving feedback signal, and described feedback signal is to turn from described inverse-excitation type The voltage at the first inducer two ends of parallel operation is derived, and wherein said feedback signal is that described controller IC is powered, and Described feedback signal is used for producing described inductor switch controls signal by described controller IC；And ground terminal, institute Stating controller IC by described ground terminal ground, described integrated antenna package is except described switch control terminal, described Outside feedback terminal and described ground terminal, no longer include other terminal.

Furthermore, present invention also offers a kind of power supply changeover device, comprising: primary inductor；Inductor switch, is couple to Described primary inductor, described inductor switch has base stage；Secondary inductor, is magnetically coupled to described primary inductor；And control Device integrated circuit processed, has internal power switch, feedback pad, base pad and ground pad, and described base pad is couple to Described internal power switch and the base stage of described inductor switch, described internal power switch is by the inducer with turn-on time Switch controlling signal disconnects, and described controller IC receives electric power by described feedback pad, and described feedback pad receives Feedback signal, described feedback signal is used for producing described inductor switch controls signal by described controller IC, and Described controller IC adjusts the turn-on time of described inductor switch controls signal in constant current mode, so that described electricity The output constant current hold of source converter.

It addition, present invention also offers a kind of method, comprising: primary inductor to be magnetically coupled to the auxiliary of power supply changeover device Helping inducer, during the turn-on time of inductor switch, inductor current flows through described primary inductor, described Power convert Utensil has controller IC, described controller IC to have feedback pad and base pad, and described power supply turns Parallel operation produces output electric current and output voltage；Receiving feedback signal on described feedback pad, described feedback signal is from described The voltage at secondary inductor two ends is derived；Utilizing described feedback signal is that described controller IC is powered；Utilize described instead Feedback signal determines described output voltage；Receiving base signal on described base pad, described base signal indicates described inductance Device electric current；Described base signal is utilized to disconnect described inductor switch；Described output electric current is determined with utilizing described base signal.

Finally, present invention also offers a kind of power supply changeover device, comprising: inductor switch, there is colelctor electrode and base stage, Described inductor switch has turn-on time；Primary inductor, is couple to the colelctor electrode of described inductor switch；Auxiliary induction Device, is magnetically coupled to described primary inductor；With the base pad of controller IC, described base pad is couple to described electricity The base stage of sensor switch, base signal existing on wherein said base pad makes described inductor switch disconnect；Be used for Receiving the device of feedback signal, described feedback signal is that the voltage from described secondary inductor two ends is derived, described feedback signal Both for powering for described controller IC, it is also used for adjusting the turn-on time of described inductor switch, so that described electricity The output voltage of source converter keeps constant.

In sum, a kind of self-oscillation flyback converter of the present invention includes being contained in and only has three below Controller IC (IC) in the IC encapsulation of terminal: ground terminal, switch control terminal and feedback terminal.Switch control terminal Son and feedback terminal are used to dual-use function.Controller IC passes through ground terminal ground.Switch control terminal is couple to external electrical The base stage of sensor switch, described external inductance on-off control flows through the electric current of the primary inductor of flyback converter.Control Device IC adjusts the turn-on time of inductor switch, so that exporting constant current hold in constant current mode and at constant voltage mode Middle output voltage keeps constant.In constant current mode, controller IC controls to flow through the peak value size of the electric current of primary inductor, with Make the output electric current of flyback converter less than scheduled current limit value.The turn-on time of inductor switch is corresponding to being used for controlling The turn-on time of the inductor switch controls signal of internal main power switch in controller IC.The drain electrode of main power switch is by opening Close control terminal and be couple to the base stage of external inductance switch.

The base signal received on switch control terminal not only makes inductor switch disconnect, but also in inductor switch Instruction about output electric current is provided during connection.Base signal indicator current flows through the speed of the primary inductor of flyback converter Rate.Inductor switch both turns off internal main power switch by inductor switch controls signal and connects, also by flowing through flyback The regenerative drives of the electric current of the secondary inductor of formula transducer and connect.The feedback signal received in feedback terminal is controller IC powers, and provides the instruction about output voltage when inductor switch disconnects.Feedback signal is from flyback converter Secondary inductor two ends voltage derive.

Although flyback converter works in constant current mode in critical conduction mode, controller IC still makes inductor switch Keep the shortest turn-off time, to prevent the efficiency of flyback converter from reducing under light load conditions.Work as flyback converter Be supported in critical conduction mode reduction and during threshold value that switch efficiency is increased to corresponding to the shortest turn-off time, inverse-excitation type Transducer becomes discontinuous conduction mode from critical conduction mode, and the highest switching frequency is restricted.

Controller IC includes automatic zero set (auto-zeroing) circuit and switched-capacitor circuit.Automatic zero set circuit leads to Cross the voltage to base signal and carry out automatic zero set so that the base-emitter bias voltage of inductor switch is eliminated, determine Flow through the electric current of primary inductor.When inductor switch is disconnected by switched-capacitor circuit, the negative voltage of feedback signal is supplied to instead One pole plate of feedforward capacitor, and will have like on the occasion of reference voltage be supplied to another pole plate of capacitor.

It addition, a kind of method operating power supply changeover device of the present invention comprises the following steps: by secondary inductor With the primary inductor that secondary inductor is magnetically coupled to power supply changeover device.Described power supply changeover device have external inductance switch and Controller IC, described controller IC has internal main power switch.The drain electrode of described internal main power switch be couple to described outside The base stage of portion's inductor switch.Described inner inductor switch by inductor switch controls signal carry out connecting with Regenerative feedback with Disconnect.

In a further step, the feedback pad of described controller IC receives feedback signal.Described feedback signal be from The voltage at described secondary inductor two ends is derived.In a further step, utilizing described feedback signal is that described controller IC is powered. In a further step, described feedback signal is utilized to determine the output voltage of described power supply changeover device.In a further step, described Base signal is received on the base pad of controller IC.The instruction of described base signal flows through the inducer electricity of described primary inductor Stream.In a further step, described base signal is utilized to disconnect described external inductance switch.Because electric current flows through described auxiliary induction Device and the regeneration that causes disconnects and also promotes described external inductance to switch off.In a further step, described base signal is utilized Determine output electric current.

In constant voltage mode, described base signal is utilized to adjust the turn-on time of described external inductance switch, with in institute The output voltage making described power supply changeover device when stating output electric current less than scheduled current limit value keeps constant.

In constant current mode, also utilize described base signal adjust described external inductance switch turn-on time, with Originally bigger output electric current is needed could to realize during the output voltage regulated, making output electric current at described scheduled current limit value Place keeps constant.

In another embodiment, a kind of power supply changeover device includes inductor switch, primary inductor, secondary inductor, base Pole pad, ground pad and for receiving the device of feedback signal.Described base pad and ground pad are positioned on controller IC. In addition to by described base pad, described ground pad and described device, electric current is not had to be delivered to described controller IC or from institute State controller IC to pass out.Described inductor switch has colelctor electrode and a base stage, and shows and have turn-on time.Described primary Inducer is couple to the colelctor electrode of described inductor switch.Described secondary inductor is magnetically coupled to described primary inductor.Described Base pad is couple to the base stage of described inductor switch.

Base signal present on described base pad makes described inductor switch disconnect, and is used for adjusting described inducer The turn-on time of switch, so that the output constant current hold of described power supply changeover device.The feedback signal that described device receives is Voltage from described secondary inductor two ends is derived, for powering for controller IC, and for adjusting the connection of inductor switch Time, so that the output voltage of power supply changeover device keeps constant.

Can obtain further by following accompanying drawing explanation and detailed description of the invention about the advantages and spirit of the present invention Understanding.

Accompanying drawing explanation

With detailed description of the invention the present invention is described in further detail below in conjunction with the accompanying drawings and is wherein identically numbered instruction Identical assembly.

Fig. 1 is the most controlled in prior art and has the simplification of self-oscillation flyback converter of discrete assembly Schematic diagram.

Fig. 2 is the most controlled in prior art and has the simplification of self-oscillation flyback converter of discrete assembly Schematic diagram.

Fig. 3 is the simplification signal with the self-oscillation of controller IC (IC), primary side controlled flyback converter Figure, described controller IC is contained in the integrated antenna package only with three pins.

Fig. 4 is the figure showing idealization waveform, the behaviour of flyback converter shown in these idealizations waveform graphic extension Fig. 3 Make.

Fig. 5 is the more detailed schematic diagram of the controller IC only with three pads of Fig. 3.

Fig. 6 is in constant current mode and flows through the peak electricity of secondary inductor of Fig. 3 flyback converter in constant voltage mode Flow time dependent schematic diagram.

Fig. 7 is the output voltage-output current diagram of Fig. 3 flyback converter, and its display is at constant current mode, constant voltage mould Working region in formula, critical conduction mode and discontinuous conduction mode.

Fig. 8 is the operational factor table of another embodiment of Fig. 3 flyback converter, depending on input line voltage, described Flyback converter becomes discontinuous conduction mode from critical conduction mode under different output current loading levels.

Fig. 9 is by adjusting the output electric current controlling Fig. 3 flyback converter turn-on time of inductor switch and electricity The flow chart of the method for pressure.

Figure 10 is under high and low AC input line voltage, the crest voltage limit value of Fig. 3 flyback converter and load cycle it Between relation schematic diagram.

Detailed description of the invention

Reference will now be made in detail to now certain embodiments of the present invention, the example of these embodiments is illustrated in the accompanying drawings.

Fig. 3 is the figure of flyback converter 35, and flyback converter 35 has the control being encapsulated in integrated antenna package 37 Device integrated circuit (IC) 36 processed.Although term " integrated circuit " is usually used in both representing integrated circuit, also illustrates that and wherein accommodate collection Become the integrated antenna package of circuit, but term used herein " integrated circuit " only represents integrated circuit die (die).Flyback Formula transducer 35 includes the transformator 38 for input voltage is converted into different output voltage.Transformator 38 includes primary inductance Device (winding) 39, secondary inductor 40 and secondary inductor 41.Primary inductor 39 has N_PCircle；Secondary inductor 40 has N_S Circle；And secondary inductor 41 has N_ACircle.

In one embodiment, input voltage is the voltage from wall plug, and output voltage is then for portable electric Child user device (such as mobile phone or portable electronic device) is charged.Inductor switch Q in transducer 35₁ During 42 connection, inductor current (I_LP) 43 begin flow through primary inductor 39.Ramped up by primary inductor 39 at electric current When to peak value and stopping subsequently, energy is transmitted to secondary inductor 40 in the magnetic field of the collapse around primary inductor 39.Electric current is opened The peak value begun when flowing through secondary inductor 40 is by turn ratio and the peak point current I flowing through primary inductor 39_PEAKRelevant.Electric current It is then out secondary inductor 40, to secondary side rectifier diode D₁44 apply forward bias, and are injected into output capacitor 45 In.The energy being delivered to secondary inductor 40 is defeated as output electric current from flyback converter 35 under different output voltages Go out.In some applications, such as in the application that electric user devices is charged, it is desirable to prevent exporting electric current and exceed predetermined Current limit.

Fig. 4 shows the idealization waveform on each node of flyback converter 35.These waveform graphic extension inverse-excitation types The operation of transducer 35, including inductor switch Q₁How 42 switch on and off.Controller IC 36 flows through primary electrical by adjustment The peak point current of sensor 39, controls the output voltage (V of flyback converter 35_OUT) and output electric current (I_OUT).By controlling electricity Sensor switch Q₁The time that switches on and off of 42 adjusts peak point current.Flyback converter 35 works with both of which: constant current Pattern and constant voltage mode.In constant current mode, controller IC 36 controls inductor switch Q₁The turn-on time of 42, so that primary Inductor current I_LP43 stop moment (T when increasing₃) corresponding to current detection signal (V_CS) 46 reach peak point current limit value (V_IPK) time moment.In constant voltage mode, controller IC 36 controls inductor switch Q₁The turn-on time of 42, so that primary Inductor current I_LP43 stop moment (T when increasing₃) corresponding to current detection signal (V_CS) 46 reach error voltage (V_ERROR) time moment, wherein error voltage (V_ERROR) less than peak point current limit value (V_IPK).Error voltage V_ERRORIt is by inciting somebody to action Reference voltage and the voltage (V of the feedback signal 47 from secondary inductor 41 derivation_FB) compare and produce.

In the fig. 3 embodiment, inductor switch Q₁42 is outside npn bipolar transistor.Controller IC 36 has base stage Pad 48, feedback pad 49 and ground pad 50.Owing to electric current is delivered to controller IC 36 by only three pads, thus collect Circuit package 37 is become only to have three terminals: switch control terminal 51, feedback terminal 52 and ground terminal 53.Integrated antenna package Each terminal all increase cost.Therefore, manufacture controller IC 36 ratio being encapsulated in integrated antenna package 37 and manufacture needs Encapsulation is made to have the controller IC of more than three terminal cheap.

By utilizing feedback signal 47 to power for controller IC 36, just it is no longer necessary to use extra terminal, this feedback letter Numbers 47 also comprise the instruction output voltage V when inductor switch 42 disconnects_OUTInformation.Additionally, by utilizing base signal 54 Disconnect inductor switch Q₁42, just it is no longer necessary to another terminal, this base signal 54 comprises instruction when inductor switch Q₁42 connect Output electric current (I time logical_OUT) information.By eliminating the second external transistor of prior art self-oscillating converter, produce Cost is minimized.The comparator in controller IC 36 is used to replace the second external transistor to realize self-oscillation.

In another embodiment, inductor switch Q₁42 is outside switch mosfet.In another embodiment, inducer Switch Q₁The field-effect transistor (FET) that 42 are integrated in controller IC 36.

In the fig. 3 embodiment, base pad 48 is connected to switch control terminal 52 by bonding wire.Controller IC 36 profit Inductor switch Q is controlled with switch control terminal 51₁42 and receive about output electric current I_OUTInstruction.Feedback pad 49 leads to Cross another bonding wire and be connected to feedback terminal 52.Controller IC 36 receives power and output voltage V by feedback terminal 52_OUTFinger Show.Depending on type according to encapsulation, switch control terminal 51, feedback terminal 52 and ground terminal 53 can be low cost three pins Three lead-in wires of formula TO-92 transistor outline package or three lead-in wires of SOT-23 small-geometry transistor.The most integrated electricity Road encapsulation 37 is in the embodiments of three pinned TO-92 encapsulation, it is allowed to controller IC 36 is contained in be generally used for accommodating single In the low-cost package of transistor.

Except controller IC 36, IC encapsulation 37, transformator 38, npn bipolar transistor 42, secondary side rectifier diode D₁ 44 Outside with output capacitor 45, flyback converter 35 also includes diode rectifier bridge 57, starting resistance R_START58, emitter resistance R_E59, R/C network 60, resistor voltage divider network 61, primary side commutation diode D₂62, resistance 63 and two capacitor 64-65. Flyback converter 35 does not have secondary-side control circuitry and photo-coupler.Diode rectifier 57 is AC/DC bridge, for by wall On exchange be converted into the direct current of pulsation.The first embodiment of transducer 35 is configured in constant current mode produce 600mA's Output electric current I_OUTWith the output voltage V producing 5 volts in constant voltage mode_OUT.In the first embodiment, diode rectifier 57 can Accept to be in the AC-input voltage in the range of 85-265 lies prostrate.In first embodiment, the value of resistance and electric capacity is: R₁13.8k Ω, R₂21.9k Ω, R₃1.8k Ω, R_E4.3 Ω, R_START3 × 2.2M Ω, and C_B10 nanofarads.Described inducer has following circle Number: N_p99, N_s8 and N_A 9。

Inductor switch Q₁42 is main by the positive Regenerative feedback from secondary inductor 41 rather than by from controller IC The switching signal conducting of 36.But, the inductor switch controls signal 67 that controller IC 36 produces allows electric charge at inductance really Device switch Q₁Gather in the base stage of 42, in order to start the process of regenerative drives.When first flyback converter 35 is connected, electricity Sensor switch controlling signal 67 makes the main power switch Q in controller IC 36₂68 stay open (open).This flows through starting Resistance R_STARTThe input current of 58 is in inductor switch Q₁Gather in the base stage of 42.In one embodiment, starting resistance R_START58 resistance with about 6.6M Ω.

When inductor switch Q₁Voltage (V in the base stage of 42_BASE) it is increased beyond the base stage of npn bipolar transistor 42-penetrate Pole conducting voltage (V_BE) time, the inductor current from primary inductor 39 begins flow through inductor switch Q₁42.But, only Have when flowing through resistance R_STARTThe starting current of 58 current gain by transistor 42 and the auxiliary/primary turns ratio of inducer (N_A/N_P) amplify (this can form positive Regenerative feedback) time, inductor switch Q₁42 is the most fully switched on.Secondary inductor 41 magnetic coupling To primary inductor 39, thus when electric current begin through primary inductor 39 ramp up time, the band point end of secondary inductor 41 Voltage (V_AUX) raise immediately.The magnetic coupling of primary inductor and secondary inductor is in the diagram by the band point of secondary inductor 41 Voltage (V on end_AUX) and primary inductor 39 without the voltage (V on an end_COL) (it is equivalent to inductor switch Q₁42 Voltage on colelctor electrode) waveform illustrate.The band point end of secondary inductor 41 is couple to inductor switch Q by R/C network 60₁ The base stage of 42.The stop capacitor C of R/C network 60_BPull-up base voltage when 69 voltages at secondary inductor 41 two ends raise V_BASE, and inductor switch Q₁42 connect rapidly.Inductor switch Q₁In the colelctor electrode of 42 and thus electric current in emitter-base bandgap grading Ramping up with a rate linear now, this speed is by the inductance (L of primary inductor 39_P) and input voltage (V_IN) limit.

Fig. 5 is the more detailed schematic diagram of controller IC 36.In addition to main power switch 68, controller IC 36 also includes out Pass capacitor circuit 70, automatic zero set circuit 71, feedback signal detector 72, error comparator 73, switching logic 74, grid drive Dynamic device 75, under-voltage locking and excess voltage protection (OVP) 76, preamplifier 77, traffic filter 78, error amplifier 79, DC flexible cord (cord) compensates circuit 80, peak point current manipulator 81, power capacitor (C_P) 82, line-voltage regulator (D₃) 83, diode (D₄) 84 and capacitor 85.Switched-capacitor circuit 70 includes feedback condenser (C_FB) the 86, first switch (S₁) 87, second switch (S₂) the 88, the 3rd switch (S₃) 89 and current source 55.Automatic zero set circuit 71 includes the capacitor (C that returns to zero_Z)90、 4th switch (S₄) 91 and diode (D₅)92.Peak point current manipulator 81 includes accurate voltage clamp circuit (D₆)93。

Now with Fig. 5, inductor switch Q is described₁How 42 disconnect.Utilize the electric current I flowing through primary inductor 39_LP 43 determine when disconnection inductor switch Q₁42.Flow through emitter resistance R_EThe electric current of 59 approximates and flows through primary inductor 39 Electric current I_LP43.As primary inductor current I_LP43 increase and flow out inductor switch Q₁42 emitter-base bandgap grading time, base signal The base voltage V of 54_BASEAlso increase.Base voltage V_BASEEqual to emitter resistance R_EVoltage (the V at 59 two ends_RE) bipolar plus NPN Base-emitter offset voltage (the V of transistor 42_BE).Therefore,

V_BASE=V_BE+V_RE. (94)

In one embodiment, Base-emitter offset voltage V_BEIt is about 0.7 volt.Therefore, primary inductor electric current I_LP 43 Approximation as the following formula with emitter resistance R_EThe voltage drop V at 59 two ends_RERelevant:

V_RE=I_LP·R_E. (95)

Equation 95 does not considers the base current error of npn bipolar transistor 42.(actually V_RE=(I_LP+I_BASE)·R_E)。 By by combined for equation 94 and 95, by primary inductor electric current I_LP43 are described as on the base pad 48 of controller IC 36 The base voltage V of the base signal 54 received_BASEFunction:

I_LP=(V_BASE-V_BE)/R_E. (96)

Therefore, can be by from base voltage V_BASEIn deduct Base-emitter offset voltage (V_BE) detect and flow through primary electrical The electric current I of sensor 39_LP.As mentioned below, automatic zero set circuit 71 is from base voltage V_BASEIn deduct Base-emitter offset voltage (V_BE) and produce current detection voltage V_CSSo that

I_LP=V_CS/R_E. (97)

As base voltage V_BASEDeduct base-emitter voltage V_BE(the voltage V such as current detection signal 46_CSShown in) reach permanent Error voltage V in die pressing type_ERROROr peak point current limit value V in constant current mode_IPKIn less one time, inductor switch Q₁ 42 Disconnect.Error comparator 73 is by current detection voltage V_CSError voltage V with error signal 98_ERROROr modulate with peak point current Peak point current limit value V produced by device 81_IPKCompare.Error voltage V_ERRORBe designated as acquisition transducer 35 is regulated output Voltage and the size of current that needs.In constant current mode when transducer 35 heavy service, regulated output voltage can obtained Before, output electric current reaches peak point current limit value V_IPK.Therefore, in constant current mode, error comparator 73 is by current detection voltage V_CSWith peak point current limit value V_IPKCompare.

Voltage V corresponding to predetermined output current limit_IPKIt is set equal to acquisition desired by peak point current manipulator 81 Current detection voltage V during output electric current_CS.In the constant current mode that transducer 35 works in critical conduction mode, export electric current It is represented by the function of total cycle time rather than the function of switching frequency.Total cycle time why can be used to replace switch lock Rate, the switching frequency being because in critical conduction mode is the inverse of the total time of current ramp rising or ramp down.Therefore, Output electric current I_OUTCan be described as simplify equation:

I_OUT=1/2 I_LP·{1-T_ON/(T_ON+T_OFF)}·(N_P/N_S)·η (99)

Wherein I_LPIt is the peak point current flowing through primary inductor 39, T_ONAnd T_OFFIt it is inductor switch Q₁42 connect on and off ETAD expected time of arrival and departure, η is efficiency.Item T_ON/(T_ON+T_OFF) it is load cycle.In one embodiment, efficiency is about 80%.It should be noted that In constant current mode, output electric current and the inductance L of primary inductor 39_PUnrelated.By combined for equation 97 and 99 available:

I_OUT=1/2 (V_CS/R_E)·{1-T_ON/(T_ON+T_OFF)}·(N_P/N_S)·η (100)

According to equation 100, voltage V_IPKIt is set equal at given R_EDesired maximum output electricity is obtained under the conditions of value Stream I_OUTCurrent detection voltage V_CS.Equation 100 shows, exports electric current I_OUTChange with the change of AC input line voltage.Such as, When AC input line voltage is multiplied to 220V from 110V, turn-on time T_ONTo halve, simultaneously switch off time T_OFFKeep constant, and And therefore export electric current I_OUTTo change according to equation 100.But when meeting following formula, export electric current I_OUTWith input line voltage without Close:

I_LP·{1-T_ON/(T_ON+T_OFF)=0.576V/ (R_E+R_VBE) (101)

Its middle term R_VBECompensate when flowing through inductor switch Q₁42 curent change time base-emitter voltage change.Work as stream Cross inductor switch Q₁When the electric current of 42 increases, base-emitter voltage V_BEIncrease.Such as, 220mA is increased to when electric current from 20mA And when npn bipolar transistor 42 is used parts 13002, the change of base-emitter voltage is about 62mV, this can be by being about The resistance R of 0.31 Ω_VBECompensate.In the present embodiment, R_VBEIt is empirically to be determined.Therefore, when being described as the following formula Resistance R for emitter resistance 59_EFunction time, output electric current just with input line voltage and R_VBEChange unrelated:

I_OUT=1/2 0.576V/ (R_E+R_VBE)·(N_P/N_S)·η (102)

Equation 102 is utilized to choose the resistance R of emitter resistance 59_E, result is obtained by current detection voltage V during equation 100_CS Corresponding identical desired output electric current.

Constant current mode

In constant current mode, flow through emitter resistance R_EThe electric current of 59 increases, until current detection voltage V_CSEqual to peak electricity Restriction value V_IPK.Then, error comparator 73 saltus step, and switching logic 74 utilize from error comparator 73 output pulse width Degree signal produces " N-channel conducting " (NCHON) signal 103.The output of error comparator 73 is for entering the switch of transducer 35 Horizontal pulse frequency and width modulated (PFWM) control.Gate drivers 75 utilizes N-channel Continuity signal 103 to produce inductor switch Control signal 67.Gate drivers 75 is the MOSFET gate drivers of high relative velocity.Inductor switch controls signal 67 quilt (asserted) is set and closes main power switch Q₂68.From inductor switch Q₁The base stage of 42 gives off electric current, and electricity Sensor switch Q₁42 begin breaking.According to common inverse-excitation type action, when electric current stops running through primary inductor 39, transformation The voltage at all inducer two ends of device 38 all inverts.Such as, the voltage on the band point end of secondary inductor 41 becomes negative value.Cause The regeneration disconnection that electric current flows through caused by secondary inductor 41 and R/C network 60 can strengthen inductor switch Q₁The disconnection of 42.Should Drop-down inductor switch Q of electric current₁The base stage of 42, so that inductor switch Q₁42 disconnect rapidly.

Inductor switch Q₁42 remain open, until all energy being stored in primary inductor 39 are all delivered to secondary Level inducer 40 and from transducer 35 export till.When electric current is no longer flow through arbitrary inducer, the voltage at inducer two ends Moment (T in the diagram₄) begin to decline zero.Feedback signal detector 72 detects when the negative feedback voltage of feedback signal 47 V_FBAt T₄Moment starts to collapse and anti-phase.T is detected at feedback signal detector 72₄During the moment, inductor switch controls signal 67 at T₅Moment Guan Bi main power switch Q₂68.Flow through starting resistance R_STARTThe input current of 58 starts in inductor switch Q₁ Gather in the base stage of 42, and positive Regenerative feedback is at T₆Moment connects inductor switch Q₁42, and start new circulation.Connect With disconnection inductor switch Q₁The positive Regenerative feedback of 42 and regeneration disconnection make transducer 35 self-oscillation.

Automatic zero set circuit 71 produces current detection voltage V_CS, error comparator 73 is by itself and error voltage V_ERRORCarry out Relatively.Automatic zero set circuit 71 utilizes zeroing capacitor C_Z90 from base voltage V_BASEIn deduct Base-emitter offset voltage V_BE.In inductor switch Q₁During 42 disconnection, inductor switch Q₁Voltage V in the base stage of 42_BASE(being indicated by base signal 54) It is grounded.Additionally, when inductor switch Q₁During 42 disconnection, the 4th switch S₄91 Guan Bis, thus will zeroing capacitor C_Z90 couplings Receive diode (D₅)92.Diode (D₅) 92 be chosen and inductor switch Q₁The Base-emitter offset voltage V of 42_BETool There is identical voltage drop.Therefore, in inductor switch Q₁42 connect and the 4th switch S₄After 91 open, return to zero capacitor C_Z Voltage on two pole plates of 90 is the V of a times_BE.Feedback signal detector 72 detect feedback signal 47 the most anti-phase and become Height, this shows inductor switch Q₁42 are connecting and base voltage V_BASEFrom the V of a times_BERamp up.At inductance Device switch Q₁42 when being initially turned on, and feedback signal detector 72 opens the 4th switch S₄91, so that current detection signal V_CS 46 Start from zero volt rather than from the V of a times_BERamp up.Therefore, when current detection signal 46 is first begin to tiltedly become, by base Pole-emitter-base bandgap grading offset voltage V_BEZero setting.Due to Base-emitter offset voltage V_BEWith flowing through inductor switch Q₁The increasing of the electric current of 42 Increase greatly, thereby through adjusting the voltage V corresponding to peak point current limit value_IPKCompensate Base-emitter offset voltage V_BEWith electricity The change that stream increases.Adjusting voltage V_IPKTime, the change of peak point current manipulator 81 applied current and Base-emitter offset voltage V_BEChange between well-known relation.The V caused because of curent change_BEChange is expressed as:

$\mathrm{\Δ}{V}_{\mathrm{BE}}=\frac{\mathrm{KT}}{q}\·\ln \left(\frac{I_1}{I_2}\right)---\left(104\right)$

Wherein K is Boltzmann constant (Boltzmann ' s constant), and T is absolute temperature, and q is electron charge, I₁ It is primary current, and I₂It it is the electric current after change.

Constant voltage mode

In constant voltage mode, due to error voltage V_ERRORLess than the voltage V corresponding with peak point current limit value_IPK, thus by mistake Difference comparator 73 is by current detection voltage V_CSError voltage V with error signal 98_ERRORCompare.When inductor switch Q₁ 42 During disconnection, the negative feedback voltage V of feedback signal 47_FBInstruction output voltage V_OUT.Voltage on the band point end of secondary inductor 41 V_AUXBe secondary inductor 40 without the voltage V on an end_SIt is multiplied by turn ratio N_A/N_SThe opposite number of result.Voltage V_SIt is equal to Output voltage V_OUTPlus secondary side rectifier diode D₁44 both end voltage fall V_D1.Therefore,

V_AUX=-(V_OUT+V_D1)·N_A/N_S. (105)

Therefore, the feedback voltage V on feedback pad 49_FBIt is represented by:

V_FB=-(V_OUT+V_D1)·N_A/N_S·R₂/(R₁+R₂). (106)

In constant voltage mode, controller IC 36 is by feedback voltage V_FBAbsolute value be adjusted to equal to line-voltage regulator D₃Reference voltage V produced by 83_REF.During regulating, the output voltage of transducer 35 is:

$V_{\mathrm{OUT}}=V_{\mathrm{REF}}\·(1+\frac{R_1}{R_2})\left(\frac{N_S}{N_A}\right)-V_{D1}.---\left(107\right)$

Switched-capacitor circuit 70 is for making feedback condenser (C when transducer 35 is adjusted and running_FB) 86 with phase Anti-but equal electric charge.Line-voltage regulator 83 is accurate shunt regulator reference, for higher than 3.45V ± 2% The reference voltage time-division pour off excess electric current.Such as, line-voltage regulator D₃83 is accurate shunt regulator.Work as inductance Device switch Q₁During 42 connection, the voltage of feedback signal 47 is high, and when line-voltage regulator is released from feedback signal 47 Electric current time, power capacitor C_P82 are charged to 3.45 volts, and power capacitor 82 can be charged to be higher than by this electric current originally 3.45 volt.

When feedback signal 47 provides the biggest electric current, under-voltage locking and excess voltage protection (OVP) 76 protection Controller IC 36.In one embodiment, if after the turn-on time of 0.5 second, feedback signal 47 delivers to OVP 76 and is more than The electric current of 1.15mA, then base pad 48 is shorted to ground, until V_REFTill being released to 1 volt.Generally, this consumes about 1 millisecond Time.Then, input voltage is to the voltage V on base pad 48_BASERecharge, until positive Regenerative feedback recovers switching manipulation Till.

All elements of controller IC 35 are by power capacitor C_P82 power supplies.For simplicity's sake, the most only illustrate Power line towards error amplifier 79.

When inductor switch Q₁During 42 connection, second switch (S₂) 88 and the 3rd switch (S₃) 89 all close, and first Switch (S₁) 87 open.Therefore, at feedback condenser C_FBWith the reference voltage of 3.45 volts on the top crown of 86.From capacitor 86 is high impedance to the input of preamplifier 77 and excess voltage protection (OVP) 76, thus upper at feedback condenser 86 The voltage of 3.45 volts is kept on pole plate.Switch 87-89 is that the control signal produced by switching logic 74 is controlled, and this control is believed Number being similar to N-channel Continuity signal 103, simply this control signal is at T₄Rather than T₅Moment is cancelled setting (deassert).Feedback Sampler detection negative feedback voltage V in signal detector 72_FBAt T₄Moment starts the moment of collapse.At T₄Moment inducer Switch Q₁Before 42 i.e. will be switched off, switched-capacitor circuit 70 is by opening second switch (S₂) 88 and the 3rd switch (S₃) 89 also Guan Bi the first switch (S₁) 87 detect by the output voltage V indicated by equation 106_OUT.It is adjusted running at transducer 35 Time, this makes feedback condenser C_FBThe bottom crown of 86 is with negative feedback voltage V_FB, and the voltage on top crown is pulled down to zero volt. Therefore, as negative feedback voltage V_FBIn turn-off time due to auxiliary winding 41 finite resistance and during towards zero volt slow-decay, At feedback condenser C before switching 87-89 reversion and voltage being sampled_FBFeedback voltage present on the bottom crown of 86 V_FBFinal voltage level be T₄The negative feedback voltage V in moment_FB.(in the waveform of Fig. 4, for ease of graphic extension, exaggerate Negative feedback voltage V during turn-off time_FBDecay towards zero volt.)

Ground signalling and zero Volt signal amplify through preamplifier 77, and switching transients amount is filtered through traffic filter 78 Remove.Error amplifier 79 by ground signalling compared with the zero volt on top crown, and when transducer 35 is adjusted Find that the two is equal.When transducer 35 is adjusted, error voltage V_ERRORDo not change, and by error comparator The turn-on time that the pulse width signal of 73 outputs is dominated does not changes.Error amplifier 79 is trsanscondutance amplifier, because It receives input voltage difference and exports the electric current being directly proportional to this difference.Error amplifier 79 output error signal 98, wherein Flow to the electric current on capacitor 85 and produce error voltage V_ERROR。

When transducer 35 runs and is exporting too high voltage on regulation, V_AUXAnd feedback voltage V_FBNegative It is worth the most excessive.Therefore, feedback condenser C_FBThe top crown of 86 is pulled to below earth potential.Error amplifier 79 output diminishes Error voltage V_ERROR, the tiltedly current detection signal V of change_CS46 can reach this voltage quickly.From error comparator 73 output Pulse width signal produces the inductor switch controls signal with shorter turn-on time.Owing to turn-on time shortens, by just The peak point current that level inducer 39 ramps up reduces, and the energy being delivered to primary side reduces.Therefore, output voltage drop Low, in order to enter adjustment state.

In constant voltage mode, DC flexible cord compensates circuit 80 and provides output flexible cord resnstance transformer automatically.The most usual The output flexible cord correction of about 3% increases in error signal 98.DC flexible cord compensates and can compensate for being caused by the resistance of output flexible cord Output voltage drop, thus improve the degree of accuracy of output voltage.

Discontinuous conduction mode

The switching frequency of transducer 35 depends on its resonance characteristic, including the inductance L of primary inductor 39_P, primary and secondary Turn ratio N of level inducer_P/N_S, and the electric current of reflective loads and voltage.In the perseverance that transducer 35 works in critical conduction mode In stream mode, switching frequency is inductor switch Q₁The turn-on time of 42 and the inverse of sum turn-off time.Turn-on time can table It is shown as:

$T_{\mathrm{ON}}=\frac{I_{\mathrm{OUT}}}{V_{\mathrm{OUT}}}\·\frac{2\·L_P\·V_{\mathrm{OUT}}/V_{\mathrm{IN}}}{N_P/N_S}\·(1+\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}\·\frac{N_P}{N_S}).---\left(108\right)$

Turn-off time is represented by:

$T_{\mathrm{OFF}}=\frac{I_{\mathrm{OUT}}}{V_{\mathrm{OUT}}}\·\frac{2\·L_P}{{(N_P/N_S)}^2}\·(1+\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}\·\frac{N_P}{N_S}).---\left(109\right)$

Switching frequency is represented by:

$f_{\mathrm{OSC}}=\frac{V_{\mathrm{OUT}}\·{(N_P/N_S)}^2}{2\·L_P\·I_{\mathrm{OUT}}\·{(1+\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}\·\frac{N_P}{N_S})}^2}.---\left(110\right)$

Wherein V_OUT/V_INFor D/C voltage conversion ratio.

Fig. 6 is the time dependent figure of peak point current flowing through secondary inductor 40 in constant current mode and constant voltage mode. Each peak value is all similar to the electric current that flyback converter 35 exports in a switch periods.Such as, normally filling at battery In electricity order, charging process starts in cycle #1 with constant current mode and enters constant voltage mode in cycle #9.Start at battery Incipient stage during charging, the pack heaviest of transducer 35.This load pulls the electric current more than predetermined output current limit, and Transducer 35 is limit value output electric current in constant current mode.Carrying out and the reduction of load, flyback converter along with battery charging 35 reduce peak point current, to maintain constant voltage after cycle #8.When reaching light load threshold in cycle #17, inverse-excitation type Transducer 35 becomes discontinuous conduction mode, and inductor switch Q from critical conduction mode₁Keep the turn-off time of 42 constant.

Fig. 7 is the output voltage-output map of current of flyback converter 35.Numeral along curve corresponds to Fig. 6 each cycle Peak point current.Normal charging process starts from a #1 and proceeds to a #23.When output voltage drops to the event being illustrated by the broken lines Time below barrier threshold value, break down state.When output voltage drops to below fault threshold, anti-present on feedback pad 49 Feedthrough voltage (V_FB) drop to below under-voltage locking disconnection threshold value, and switching manipulation stops.In one embodiment, if After the turn-on time of 0.5 microsecond, feedback signal 47 does not delivers the electric current of at least 0.06mA to UVLO and OVP 76, then reach to owe electricity Press off lock and disconnect threshold value.When reaching this disconnection threshold value, base pad 48 is shorted to ground, until V_REFTill being released to 1 volt.So After, input voltage is to voltage (V present on base pad 48_BASE) recharge, until positive Regenerative feedback recovers switching manipulation Till.

Along with transducer 35 enters constant voltage mode, error voltage V_ERRORDrop to the voltage corresponding to peak point current limit value V_IPK.Then, error comparator 73 is by current detection voltage V_CSError voltage V with error signal 98_ERRORCompare, and make to connect The logical time reduces.Electric current flows through primary inductor 39 and ramps up a relatively short period of time cycle.Electric current flows out secondary inductor Turn-off time during 40 also shortens.Owing to transducer 35 is free-running, thus turn-on time is total plus being equal to turn-off time Circulation time, and switching frequency increase, to prevent output voltage from exceeding set maximum.When battery is fully charged, Load reduces and switching frequency becomes more and more higher, to prevent output voltage from exceeding regulation voltage.

But, under the highest switching frequency, along with switching loss rises, the efficiency of flyback converter reduces.For Keeping high efficiency when to light load charging, switching logic 74 produces the N-channel Continuity signal with minimum turn-off time 103.Even as electric current I_SWhen stopping running through secondary inductor 40, main power switch Q₂68 turn-off times also staying open minimum And do not allow inductor switch Q₁42 connect.As electric current I_SDischarge time when becoming shorter than minimum turn-off time, inverse-excitation type Transducer 35 becomes discontinuous conduction mode from critical conduction mode.This change between Fig. 7 graphic extension point #16 and #17.One In individual embodiment, this minimum turn-off time is 10 microseconds, and this is corresponding to making primary inductor electric current I_LP43 tiltedly change to peak point current Horizontal I_IPK70% needed for time.

In critical conduction mode, switching frequency depends on AC input line voltage.Input line voltage is the highest, transmits equal amount Energy needed for time the shortest.Therefore, for the highest input line voltage, it is thus achieved that frequency used during regulated voltage is more High.In one embodiment, transducer 35 becomes Discontinuous Conduction mould when reaching identical load level from critical conduction mode Formula.In order to identical load level switch mode, controller IC 36 adjusts minimum turn-off time, so that transducer 35 is more Discontinuous conduction mode is entered with the highest frequency under high input line voltage.Such as, from critical conduction mode (CRM) to discontinuously leading The transformation of logical pattern (DCM) is to occur, then about under high input line voltage when about 60kHz under low input line voltage Occur during 100kHz.

Fig. 8 is the table of the operational factor of another embodiment of transducer 35, and depending on input line voltage, transducer 35 exists Discontinuous conduction mode is become from critical conduction mode under different output current loading levels.These operational factors are for output The embodiment of 2.75 watts of power (5V/0.55A).Under the low AC input line voltage of 110 volts, transducer 35 is being set below Discontinuous conduction mode is become under the output current loading of 25%.And under the high AC input line voltage of 220 volts, transducer 35 is about Discontinuous conduction mode is become under the set output current loading of 50%.Fig. 8 also lists and can make under low or high input line voltage Peak current level I that transducer 35 runs under listed output current loading level most effectively_PEAK。

Fig. 9 is flow chart, step 111-119 of the operational approach of the flyback converter 35 of its graphic extension Fig. 3.The party Method adjusts inductor switch Q by utilizing inductor switch controls signal 67₁The turn-on time of 42, control inverse-excitation type conversion Output electric current (the I of device 35_OUT) and output voltage (V_OUT)。

In first step 111, secondary inductor 40 and secondary inductor 41 are magnetically coupled to the first inducer 39.Work as electricity Sensor electric current 43 moment T in the diagram₁Begin through primary inductor 39 when ramping up, secondary inductor 41 and dividing potential drop electricity The feedback voltage V of feedback signal 47 produced by resistance network 61_FBRaise rapidly.Feedback signal 47 is from secondary inductor 41 two ends Voltage derive.

In step 112, the feedback pad 49 of controller IC 36 receives feedback signal 47.

In step 113, feedback signal 47 is utilized to power for controller IC 36.Feedback signal 47 is by diode D₄ 84 Electric current is provided and power capacitor C is provided to_POn 82.Electric current from power capacitor 82 is each parts of controller IC 36 (such as error amplifier 79, feedback signal detector 72 and error comparator 73) powers.

In step 114, feedback signal 47 is utilized to determine the output voltage V of transducer 35_OUT.When inductor switch Q₁42 During disconnection, the size of the negative voltage of feedback signal 47 provides the instruction about output voltage.

In step 115, the base pad 48 of controller IC 36 receives base signal 54.When inductor switch Q₁ During 42 connection, base signal 54 provides the electric current I flowing through primary inductor 39_LPThe instruction of 43.

In step 116, base signal 54 is utilized to disconnect inductor switch Q₁42.Oblique change when current detection signal 46 Voltage V_CSReach the error voltage V of error signal 98_ERROROr the peak point current limit value V that peak point current manipulator 81 produces_IPK In smaller time, inductor switch controls signal 67 opens main power switch Q₂68 and make electric current from inductor switch Q₁ 42 Base stage release.When inductor switch Q₁42 when opening, and terminates turn-on time, and electric current I_LP43 stop passing through primary inductance Device 39 ramps up.

In step 117, base signal 54 is utilized to determine output electric current I_OUT.Base signal 54 provides and flows through primary inductance The electric current I of device 39_LPThe instruction of 43, and thus also provide for the output electric current I of transducer 35_OUTInstruction.Double by subduction NPN The Base-emitter offset voltage V of gated transistors 42_BE, produce current detection signal V from base signal 54_CS46.Output electric current I_OUTVoltage V according to equation 100 with current detection signal 46_CSRelevant.

In step 118, base signal 54 is utilized to adjust inductor switch Q₁The turn-on time of 42, with at output electric current Output voltage V is made during less than scheduled current limit value_OUTKeep constant.During constant voltage mode, as error voltage V_ERRORLess than peak value Current limit V_IPKTime, controller IC 36 controls output voltage.

In step 119, base signal 54 is utilized to adjust inductor switch Q₁The turn-on time of 42, so that at output electricity Stream I_OUTIt is held constant at scheduled current limit value.During constant current mode, as error voltage V_ERRORHigher than peak point current limit value V_IPK Time, controller IC 36 controls output electric current.Oblique time variant voltage V when current detection signal 46_CSReach peak point current manipulator 81 to produce Raw peak point current limit value V_IPKTime, terminate turn-on time.

Compensation to input line voltage change

Although AC input line voltage changes the most greatly, controller IC 36 still provides accurate constant current to run.Automatic zero set circuit 71 are used for Base-emitter offset voltage V when current detection signal 46 is first begin to tiltedly become_BEZero setting.As explained above, peak Value current modulator 81 strengthens automatic zero set, because Base-emitter offset voltage V_BEWith flowing through inductor switch Q₁The electric current of 42 Increase and increase.Base-emitter offset voltage V_BEChanging by the item R in equation 101 with the electric current increased_VBECompensate.Cause For inductor switch Q₁T turn-on time of 42_ONRelevant to input line voltage, so output electric current I_OUTChange with input line voltage Change and change.But, inductor switch Q₁T turn-off time of 42_OFFKeep constant, and export electric current I_OUTWith amount { 1-T_ON/ (T_ON+T_OFF) be directly proportional.When AC input line voltage changes, set crest voltage V_IPKTime, peak point current manipulator 81 considers (factor in) this effect.

Explained as explained above with equation 101, in constant current mode, as product I_LP·{1-T_ON/(T_ON+T_OFF) constant Time, export electric current I_OUTUnrelated with input line voltage.Therefore, peak point current manipulator 81 and value { 1-T_ON/(T_ON+T_OFF) become anti- Crest voltage V is changed than ground_IPK, so that the product of both is held equal to 0.576 volt, as when by equation 101 both sides all divided by (R_E+R_VBE) time shown.Such as, when load cycle reduces with the increase of input line voltage, for increase (1-load follow Ring) value, peak point current manipulator 81 adjusts downwards crest voltage V_IPK.Therefore, when input line voltage is higher, crest voltage V_IPK Relatively low, because reaching identical peak point current I with under relatively low input line voltage with longer load cycle_PEAKCompare, higher Identical peak point current I can be reached with shorter load cycle under input line voltage_PEAK。

Figure 10 is under sample high and low AC input line voltage, the pass between crest voltage VIPK and percent load circulation System's figure.The crest voltage of Fig. 9 and load cycle are that the primary inductor utilizing inductance to be 6.7 milihenries obtains.Peak point current is modulated Device 81 receives about TON turn-on time and the instruction of TOFF turn-off time from switching logic 74, and adjust crest voltage VIPK with Make the crest voltage VIPK product with (1-load cycle) equal to about 0.576 volt.Such as, electric when the low AC input line at 120 volts When depressing with the turn-on time of the load cycle acquisition predetermined output electric current of 36%, peak point current manipulator 81 is by crest voltage VIPK is set as 0.900 volt, so that the product of crest voltage and (1-load cycle) is equal to about 0.576 volt.When at 375 volts When obtaining the predetermined turn-on time exporting electric current with the load cycle of only 12% under high AC input line voltage, peak point current manipulator Crest voltage VIPK is set as 0.655 volt by 81, so that the product of crest voltage and (1-load cycle) is held equal to about 0.576 volt.

Although for illustration purposes, above in association with some specific embodiment the present invention is described, but the present invention not only It is limited to this.Correspondingly, can under conditions of without departing from the scope of the invention described in claim various features to described embodiment Implement various amendment, change and combine.

Claims (6)

1. the integrated antenna package under a critical conduction mode, it is characterised in that comprising:

Switch control terminal, is couple to inductor switch, and described inductor switch is by the inductor switch control with turn-on time Signal processed disconnect, be contained in the controller IC in described integrated antenna package adjust in constant current mode described connect time Between so that the output constant current hold of flyback converter, and in constant voltage mode, adjust described turn-on time so that described The output voltage of flyback converter keeps constant, receives base signal on described switch control terminal, and wherein said The electric current of the inducer of described flyback converter is flow through in base signal instruction, and described controller IC includes automatic zero set Circuit, described inductor switch shows Base-emitter offset voltage, and described base signal has voltage, and described automatically Zeroing circuit, by the voltage of described base signal carrying out automatic zero set to cut described Base-emitter offset voltage, is come really The described electric current of described inducer is crossed in constant current；

Feedback terminal, described controller IC receives electric power by described feedback terminal；And

Ground terminal, described controller IC passes through described ground terminal ground.

2. integrated antenna package as claimed in claim 1, it is characterised in that described flyback converter is free-running.

3. integrated antenna package as claimed in claim 1, it is characterised in that described integrated antenna package removes described on-off control Outside terminal, described feedback terminal and described ground terminal, no longer include other terminal.

4. integrated antenna package as claimed in claim 1, it is characterised in that described flyback converter is at described constant current mode Period works in critical conduction mode.

5. integrated antenna package as claimed in claim 1, it is characterised in that described inductor switch has base stage and current collection Pole, described switch control terminal is couple to described base stage, and described colelctor electrode is couple to described inducer.

6. integrated antenna package as claimed in claim 1, it is characterised in that receive feedback signal in described feedback terminal, And described feedback signal indicates the voltage at the inducer two ends of described flyback converter.