WO2012113140A1

WO2012113140A1 - Delay switch circuit for restraining electrical pulse current

Info

Publication number: WO2012113140A1
Application number: PCT/CN2011/071191
Authority: WO
Inventors: 潘启辉; 熊运远; 卢良飞; 冯超
Original assignee: 海能达通信股份有限公司
Priority date: 2011-02-23
Filing date: 2011-02-23
Publication date: 2012-08-30

Abstract

A delay switch circuit for restraining electrical pulse current is provided. The delay switch circuit delays the turn-on of a second switch tube using a switch delay timing network composed of a second resistance and a second capacitance. After the second switch tube is turned on, a first capacitance is charged, and then a first switch tube is turned on, thus a battery begins to charge a main circuit. The first switch tube is coupled in a main power supply loop as a delay switch. When power on, the delay switch connects the main power supply loop with an electrical source after a certain time of delay, so as to delay the turn-on of the switch. There is a transition period of resistance varying from large to small. Pulse current at the instant of power on is effectively restrained in time by the double effect of the turn-on of delay and resistance varying, so as to achieve the purposes of eliminating ignition of battery pole pieces when power on and reducing electromagnetic interference at the instant of power on.

Description

Delay switch circuit for suppressing power-on pulse current

The present invention relates to the field of switching circuits, and more particularly to a delay switching circuit for suppressing a power-on pulse current.

Background technique

The power supply circuit of a handheld device generally has a certain capacity of capacitance. At the moment of power-on, the power supply will charge these capacitors, thereby generating a large pulse current.

The high pulse current at the moment of power-on will bring two problems: First, when the contact of the battery pole pieces is unstable, these large pulse currents will generate higher heat at the contact points of the battery pole pieces, and the battery will be The pole piece is partially melted. At the same time, the air around the molten battery pole piece expands rapidly to generate an explosion, and the explosive air current brings the molten metal liquid to the surrounding air, causing spark splash. Second, the large current generated by the instantaneous charging brings strong electromagnetic interference to the surrounding space.

At present, in order to reduce the spark generated by the battery pole piece during power-on, the material of the battery pole piece, the structure and the processing technology are generally made, but this will increase the cost of the battery pole piece and can not effectively eliminate the spark phenomenon. Explosion-proof handheld devices used in flammable and explosive environments, in order to avoid sparks in the battery pole pieces, use a special structure to deadlock the battery and the handheld device to reduce the probability of battery pole jitter, but such a structure disassembles the battery Inconvenience, and, in the case of severe impact or fall, the hidden danger of sparking the battery pole piece still exists. Therefore, the method of modifying the mechanical structure can not solve the electromagnetic interference problem generated at the time of power-on.

A current limiting switch circuit is provided in the prior art, see FIG.

B+1 is the positive pole of the battery, B-1 is the negative pole of the battery, VB+ is the positive pole of the main circuit 100 of the handheld device, and VB- is the negative pole of the main circuit 100 of the handheld device.

The series current sampling resistors RD, RD in the main power supply circuit convert the operating current of the circuit into a sampling voltage, and the second switching transistor Q2 amplifies the sampling voltage and then controls the state of the first switching transistor Q1, thereby limiting the operating current of the circuit to exceed the maximum. Allow current.

Since the current is to be collected in the circuit, and then converted into a sampling voltage, and then the first switching transistor is controlled by the sampling voltage, such a current feedback control process has a delay, and the suppression of the large pulse current suddenly generated at the time of power-on is not significant, and Connecting the current sampling resistor in the main power supply circuit will cause loss, from And reduce the utilization efficiency of the battery.

Summary of the invention

The technical problem to be solved by the present invention is to provide a delay switch circuit for suppressing the power-on pulse current, which can effectively prevent the spark of the battery pole piece and reduce the electromagnetic interference generated when the device is powered on, without reducing the battery utilization efficiency.

The present invention provides a delay switch circuit for suppressing a power-on pulse current, comprising: a first switch tube, a second switch tube, a first resistor, a second resistor, a first capacitor, and a second capacitor;

The first end of the first switch tube is connected to the positive pole of the battery, and the second end is connected to the positive pole of the main circuit of the handheld device;

a first capacitor is connected between the first end and the third end of the first switch tube;

The third end of the first switch tube is connected to the second end of the second switch tube through the first resistor;

The third end of the second switch tube is grounded through the second capacitor, the first end of the second switch tube is grounded; the third end of the second switch tube is connected to the anode of the battery through the second resistor;

The negative pole of the battery is grounded, and the negative pole of the main circuit of the handheld device is grounded.

Preferably, the method further includes a first diode, the anode of the first diode is connected to the second end of the second switch tube, and the cathode is connected to the third end of the first switch tube.

Preferably, the second diode is further included, the anode of the second diode is connected to the third end of the second switch tube, and the cathode is connected to the anode of the battery.

Preferably, a third resistor connected in parallel across the first capacitor is further included.

Preferably, the fourth resistor is further included, and the third end of the second switch tube is grounded through the fourth resistor.

Preferably, the first switch tube is a field effect tube; the second switch tube is a field effect tube or a crystal triode;

When the first switch tube is a field effect transistor, the first end of the first switch tube is a source, the second end is a drain, and the third end is a gate;

When the second switch tube is a field effect transistor, the first end of the second switch tube is a source, the second end is a drain, and the third end is a gate; when the second switch tube is a crystal triode, the second switch The first end of the tube is a collector, the second end is an emitter, and the third end is a base.

The present invention also provides a delay switch circuit for suppressing a power-on pulse current, comprising: a first switch tube, a second switch tube, a first resistor, a second resistor, a first capacitor, and a second capacitor; The first end of the first switch tube is connected to the negative pole of the battery, and the second end is connected to the negative pole of the main circuit of the handheld device;

The third end of the first switch tube is connected to the positive pole of the battery through the first resistor, and the anode of the battery is simultaneously connected to the anode of the main circuit of the handheld device;

The second end of the second switch tube is connected to the third end of the first switch tube;

The third end of the second switch tube is connected to the positive pole of the battery through the second capacitor;

a first capacitor is connected between the third end of the first switch tube and the first end;

The first end of the second switch tube is grounded, the third end is connected to the negative pole of the battery through the second resistor; the negative pole of the main circuit of the handheld device is grounded.

Preferably, the first diode is further included, the anode of the first diode is connected to the third end of the first switch tube, and the cathode is connected to the anode of the battery.

Compared with the prior art, the present invention has the following advantages:

The main power supply circuit of the delay switch circuit for suppressing the power-on pulse current provided by the present invention has no current sampling resistor, so there is no problem of loss due to the resistance, and the utilization efficiency of the battery is not affected. The delay switch circuit delays the conduction of the second switch tube by using a switch delay time timing network composed of the second resistor and the second capacitor. When the second switch tube is turned on, the first capacitor is charged, and then the first switch tube is When turned on, the battery starts to supply power to the main circuit. Use this time difference to ensure that the battery pole piece is stable after contact, so that the battery pole piece can be prevented from sparking. Moreover, the delay switch circuit has no feedback line delay, and the current control speed is fast, which can effectively limit the pulse current at the time of power-on. The circuit provided by the invention effectively limits the charging pulse current at the moment of powering up the main circuit, and does not require the sampling and judging process of the current, so the current limiting is quick and effective in time. The invention utilizes delayed turn-on and suppress charge The dual function of electric current effectively eliminates the hidden danger of contact with the battery pole piece during power-on and the electromagnetic interference caused by the moment of power-on.

DRAWINGS

1 is a schematic diagram of a current limiting switch circuit provided in the prior art;

2 is a structural diagram of Embodiment 1 of a delay switch circuit for suppressing a power-on pulse current provided by the present invention; FIG. 3 is a structural diagram of Embodiment 2 of a delay switch circuit for suppressing a power-on pulse current provided by the present invention; FIG. The first switch tube on-resistance control curve;

5 is a structural diagram of a third embodiment of a delay switch circuit for suppressing a power-on pulse current provided by the present invention; FIG. 6 is a structural diagram of a fourth embodiment of a delay switch circuit for suppressing a power-on pulse current provided by the present invention; and a power-on charging current waveform Figure

Figure 8 is a waveform diagram of the input voltage, delayed output voltage, and power-on charging current of the walkie-talkie after adding the delay switch circuit of the present invention.

detailed description

The above described objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims.

Referring to Fig. 2, there is shown a block diagram of an embodiment of a delay switch circuit for suppressing a power-on pulse current provided by the present invention.

The delay switch circuit for suppressing the power-on pulse current provided in this embodiment includes: a first switch tube Q1, a second switch tube Q2, a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2;

The first end of the first switch tube Q1 is connected to the positive pole B+1 of the battery, and the second end is connected to the positive pole VB+ of the main circuit 100 of the handheld device;

a first capacitor C1 is connected between the first end and the third end of the first switch tube Q1;

The third end of the first switch tube Q1 is connected to the second end of the second switch tube Q2 through the first resistor R1; the third end of the second switch tube Q2 is grounded through the second capacitor C2, and the first end of the second switch tube Q2 Grounding

The third end of the second switch tube Q2 is connected to the positive electrode B +1 of the battery through the second resistor R2;

The negative pole B-1 of the battery is grounded, and the negative terminal VB- of the main circuit 100 of the handheld device is grounded. Wherein, R1 and CI form a current limiting integration network; R2 and C2 form a switching delay time timing network. When the charging voltage on C2 reaches the turn-on threshold voltage of Q2, Q2 turns on and C1 starts charging. When Q2 is turned on, the rise time of the bias voltage VGSQ1 of Q1 is delayed by the integral characteristics of R1 and C1. According to the control relationship between the bias voltage VGSQ1 of Q1 and the on-resistance Rds(on), during the charging of C1, there is a varistor process from infinity to full conduction during the charging of C1.

During the charging phase of C1, the bias voltage VGSQ1 of Q1 is lower and the on-resistance is larger, which can suppress the charging pulse current of the battery to the main circuit of the handheld device. As the C1 charging voltage increases,

When Q1 enters a fully-on state, the on-resistance becomes a small number of tens of ohms, and such a small resistance has little effect on the utilization efficiency of the battery.

The specific values of C1 and R1 are such that the power supply has completed the charging process of the main circuit during the transition period of Q1, so that the power-on charging current of the main circuit of the device can be effectively suppressed. It is determined that the purpose is to turn on Q1 when the contact of the battery pole piece is stable, so as to ensure that no large current flows through the pole piece of the battery during the period of unstable contact of the battery pole piece.

The specific choice of Q1 can be determined according to the working current and battery voltage of the main circuit of the handheld device and the total input capacity of the main circuit power supply terminal. It ensures sufficient voltage and power redundancy during charging of the main circuit and during normal period when Q1 is turned on. . The contact time of the battery pole piece is different depending on the material and structure of the pole piece and the time of use, which is generally less than 200ms. Therefore, the charging time of R2 and C2 is determined so that the charging voltage of C2 reaches the conduction threshold voltage of Q1 after the battery is electrically charged for more than 200 ms.

The main power supply circuit of the delay switch circuit provided by the embodiment of the invention has no current sampling resistor, so there is no problem of loss caused by the resistor, and the utilization efficiency of the battery is not affected. The delay switch circuit uses the switch delay time timing network composed of R2 and C2 to delay the conduction of Q2. When Q2 is turned on, C1 is charged, and then Q1 is turned on, and the battery starts to supply power to the main circuit. Use this time difference to ensure that the battery pole piece is stable after contact, so that the battery pole piece can be prevented from sparking. Moreover, the delay switch circuit has no feedback line delay, and the current control speed is fast, which can effectively limit the pulse current at the time of power-on.

Referring to FIG. 3, the figure is a structural diagram of a second embodiment of a delay switch circuit for suppressing a power-on pulse current provided by the invention. The circuit shown in FIG. 3 is different from that of FIG. 2 in that a first diode D1, a second diode D2, and a third resistor R3 are added;

The anode of the first diode D1 is connected to the third end of the second switching transistor Q2, and the cathode is connected to the positive pole B+1 of the battery.

The anode of the second diode D 2 is connected to the second end of the second switching transistor Q 2 , and the cathode is connected to the third terminal of the first switching transistor Q1.

A third resistor R3 is connected in parallel across the first capacitor.

The parameter values of the respective devices in this embodiment may be selected as follows:

Cl = 0.01 μ Ρ; C2 = 1 μ F; Rl = 100 kQ; R2 = 2 MQ; R3 = 1 MQ.

The first switch tube Q1 in this embodiment is preferably a P-type field effect transistor (MOS tube); the second switch tube Q2 may be an N-type field effect transistor or an NPN-type transistor triode;

When the first switch Q1 is a field effect transistor, the first end of the first switch Q1 is a source, the second end is a drain, and the third end is a gate;

When the second switching transistor Q2 is a field effect transistor, the first terminal of the second switching transistor Q2 is a source, the second terminal is a drain, and the third terminal is a gate. When the second switching transistor Q2 is a transistor, the first terminal of the second switching transistor Q2 is a collector, the second terminal is an emitter, and the third terminal is a base.

The functions of Dl, D2, R3 and R4 are to force the speeds C1 and C2 when the connection between the battery and the main circuit is interrupted to ensure that the delay and varistor function of the switch is reliable and effective during the battery chip contact jitter.

The delay switch circuit shown in FIG. 3 may further include a fourth resistor R4, and the third terminal of the second switch transistor Q2 is grounded through the fourth resistor R4.

Referring to FIG. 4, the figure shows a first switch tube on-resistance control curve provided by the present invention.

As can be seen from Figure 4, the on-resistance of Q1 has a varistor process with the change of the gate-source voltage of Q1.

The first switch tube in the delay switch circuit provided by the above embodiment is connected in series between the positive pole of the battery and the positive pole of the main circuit. Another embodiment in which the working principle is the same is described below, except that the first switch tube is connected in series to the battery. Between the negative electrode and the negative electrode of the main circuit, the first switching transistor Q1 is changed to an N-type field effect transistor.

Referring to FIG. 5, the figure is an embodiment of a delay switch circuit for suppressing a power-on pulse current provided by the present invention. Three structure diagrams.

The delay switch circuit for suppressing the power-on pulse current provided in this embodiment includes: the first switch tube

Ql, the second switching transistor Q2, the first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2;

The first end of the first switch tube Q1 is connected to the negative pole B-1 of the battery, and the second end is connected to the negative pole VB- of the main circuit 100 of the handheld device;

The third end of the first switch tube Q1 is connected to the positive pole B+1 of the battery through the first resistor R1, and the positive pole B+1 of the battery is simultaneously connected to the positive pole VB+ of the main circuit 100 of the handheld device;

The second end of the second switch tube Q2 is connected to the third end of the first switch tube Q1;

The third end of the second switch tube Q2 is connected to the anode of the battery through the second capacitor C2;

a first capacitor C1 is connected between the third end and the first end of the first switch tube Q1;

The first end of the second switch tube Q2 is grounded, and the third end is connected to the negative pole of the battery through the second resistor R1.

B+1;

Negative VB-ground of the main circuit of the handheld device.

The circuit shown in Figure 5 works in the same way as the circuit shown in Figure 2, except that Q2 is off.

Q1 can be turned on. At the instant of power-on, the positive B+1 of the battery is applied to the third terminal of Q2 through C2 to turn on Q2. During the Q2 conduction period, the second and third terminals of Q1 are shorted without a bias voltage and turned off. With the charging of C2, the voltage at the third end of Q2 drops below the turn-on threshold voltage. After Q2 is turned off, C1 begins to charge to complete the turn-on control process of Q1.

For the circuit shown in FIG. 5, the embodiment of the present invention further provides a delay switch circuit. Referring to FIG. 6, the difference from FIG. 5 is that the first diode D1 and the third resistor R3 are added.

The first diode D1 and the third resistor R3 function to accelerate the discharge of C1 and C2 when the connection between the battery and the main circuit is interrupted, thereby increasing the response speed of the delay switching circuit to the pulse voltage caused by the jitter of the battery pole piece.

In the following, the waveform diagram corresponding to the walkie-talkie circuit with the transmitting power of 5W is compared with the waveform diagram of the delay switch circuit provided by the present invention and the delay switch circuit provided by the present invention, which embodies the beneficial effects of the present invention. Late output voltage and power-on charging current waveform diagram. Referring to FIG. 8, the figure shows the waveforms of the input voltage, the delayed output voltage and the power-on charging current of the walkie-talkie after adding the delay switch circuit of the present invention.

As can be seen from Fig. 7 and Fig. 8, when the battery voltage is 7.4V, the peak value of the power-on pulse current is reduced from 12A to 0.26A, and the switching delay on-time is 428ms. It can be seen that the delay switch circuit of the present invention greatly reduces the pulse current, which can effectively prevent the battery pole piece from generating sparks.

The present invention utilizes a large resistance in the initial stage of MOS transistor conduction to limit the charging current of the main circuit voltage. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify the equivalents of equivalent changes without departing from the scope of the technical solutions of the present invention. Example. Therefore, any modification, equivalent changes, and modifications made to the above embodiments in accordance with the technical spirit of the present invention are still within the scope of the technical solutions of the present invention.

Claims

Rights request

A delay switch circuit for suppressing a power-on pulse current, comprising: a first switch tube, a second switch tube, a first resistor, a second resistor, a first capacitor, and a second capacitor;

2. The delay switch circuit according to claim 1, further comprising a first diode, the anode of the first diode being connected to the second end of the second switch tube, and the cathode being connected to the first switch tube Three ends.

3. The delay switch circuit according to claim 1, further comprising a second diode, the anode of the second diode being connected to the third end of the second switch tube, and the cathode being connected to the anode of the battery.

4. The delay switch circuit of claim 1 further comprising a third resistor coupled across the first capacitor.

5. The delay switch circuit according to claim 1, further comprising a fourth resistor, wherein the third end of the second switching transistor is grounded through the fourth resistor.

The delay switch circuit according to any one of claims 1 to 5, wherein the first switch tube is a field effect tube; and the second switch tube is a field effect tube or a crystal transistor;

7. A delay switch circuit for suppressing a power-on pulse current, comprising: a first switch transistor, a second switch transistor, a first resistor, a second resistor, a first capacitor, and a second capacitor;

The first end of the first switch tube is connected to the negative pole of the battery, and the second end is connected to the negative end of the main circuit of the handheld device Extremely

8. The delay switch circuit of claim 7, further comprising a third resistor connected in parallel across the first capacitor.

9. The delay switch circuit according to claim 7, further comprising a first diode, the anode of the first diode being connected to the third end of the first switch tube, and the cathode being connected to the anode of the battery.

The delay switch circuit according to any one of claims 7-9, wherein the first switch tube is a field effect transistor; and the second switch tube is a field effect transistor or a crystal triode;