Design of dual control drive circuit for transistor

The switch-tube drive circuit has been widely used in various electronic circuits of the transistor of fast switching operation, which can improve circuit reliability and improve circuit performance. Drive control circuitry. It is actually a control signal to the input signal power amplification circuit, to meet the load rated power to make the load normal operation, can be a certain input signal drive control, although different load needs different driving circuit, but essentially the same.

We design a two-way driving protection circuit of input pulse width adjustable signal by combining the control driving principle in analog circuit, using transistor saturation conduction and cutoff as switching control signal, and optimizing design from the aspects of drive protection and anti-jamming. The circuit has the characteristics of fast precision, high performance, miniaturization and practicability, which can meet the needs of some military and industrial automatic control systems.

Design principle and overall structure

The drive control circuit is divided into input stage circuit, amplifying stage circuit, driving circuit and protection circuit. Among them, the input stage and the amplification stage circuit consist of two identical transistor switching circuits, the driving circuit is driven out by two open collector, the protection circuit mainly utilizes the limiting function of the voltage regulator diode, and the circuit adopts dual power supply mode. Its circuit schematic diagram 1 shows.

Figure 1: Circuit schematic diagram

Figure 3 Input stage circuit

The control signal is high, the input stage switch transistor work, but the amplification switch tube does not work, the circuit output has no driving capacity; the control signal is low, the input stage switch transistor does not work, but the amplifier switch tube work, the circuit output has the drive capability. The circuit operation input and output timing diagram is shown in Figure 2

Circuit design

Circuit schematic diagram shows that the circuit is divided into input stage circuit, amplification stage circuit, drive circuit and protection circuit, the following sections are described in detail.

1 Input stage Circuit

Input stage, the control signal control the input of the same signal, two signals at a time only one input signal, not at the same time input. The input signal is a square wave of a certain amplitude when the control signal is high. The input signal is high, the transistor V1 and V2 base current I b1,2= (VCON-VBE1)/R1, the collector can provide the maximum current I c MA x1,2=v i n1/r3, select the appropriate parameters of the transistor, so βib1,2>icmax1, 2,v1 and V2 are in the saturated conduction state, V1, V2 of the collector very low level, when the control signal is low, V1 and V2 in the cut-off state, the two input signals respectively through the resistor R3, R4 added to the base of the amplification transistor.

2 Amplifier Stage Circuit

Amplification stage, two times the two input signals are amplified and sent to two drive-level circuits. When the control signal con is low, the input signal IN1, IN2 at high level, the transistor V3 and V4 base current I b3,4= (vin1-vbe3)/R3, the collector can provide the maximum current icmax3,4= (VCC-VBE5)/R9, select the appropriate transistor of the parameters, So that the Βib3,4>icmax3,4,v3, V4 in the saturated conduction state. Similarly, the V5, V6 base current ib5,6=icmax3,4-vbe5/r11,v5 and V6 collector can provide maximum current icmax5,6= (Vcc-vee-vbe7)/r13. Wherein, transistor V7 is to drive the output stage of the tube, the choice of parameters appropriate transistor, making βib5, 6>ICMAX5,6,V5, V6 saturation conduction. When the control signal con is low, the input signal is low, and the amplification level of four transistors is cut off.

Figure 4: Amplified pole circuit 5: drive and Protection circuit

3 Drive and Protection circuit

When the control signal con is level, the input signal IN1, IN2 at high level, the driver transistor V7, V8 has the drive capability, can be two transistors of the collector external load to the power supply for driving control.

The protection circuit is composed of diode V10, V11, resistor R17, R18, regulator V12, V13 and transistor V9. When the V9 conduction, the V9 conduction pressure drop Vbe9=von, the voltage regulator is reduced to VZ, the diode conduction pressure drop is VON, the Resistance R18 voltage drop VR18 About (von/r17) R18, at this time the input signal amplitude VX is about: Vcc+vr18+vz+vbe9+von, Therefore, when the output 1 or 2 end due to inductive load, the instantaneous reverse sensing electromotive force will be generated to increase its voltage. When higher than v X, V9 conduction, to achieve the limiting function, protection of V7, V10.

Validation testing and Analysis

When the amplitude of the input signal vin is 12V, the circuit simulation is performed on each part of the circuit. Using the cadence of the capture CIS simulation software ORCAD on the computer simulation simulation, simulation results 6 shows.

Figure 6: Circuit Simulation Results Figure 7: Circuit test diagram

The driving output signal of sample circuit is tested by the basic method of analog circuit parameter test. The set pulse signal is added to the input terminal IN1, at the output 1 end plus the load, with the oscilloscope test output 1-terminal output amplitude, that is, the output high and low voltage difference, the test output high level of the sharp pulse amplitude, that is, the output high to the output peak value of the difference. The output amplitude and the limiting voltage are actually measured in Figure 7.

From the simulation results of the driving circuit and the actual test results of the circuit, it is consistent with the input and output timing, and the test parameters meet the requirements of the design index, which achieves the expected goal of the design.

Conclusion

The circuit has been applied to a weapon automatic control device, the performance satisfies the requirement. It reduces the volume of the weapon system, provides the possibility to expand the function of the system, increases the combat capability, and can be used as a general control circuit directly for other similar projects, and has a good prospect of popularization and application.

(Note: This article is reproduced)

Design of dual control drive circuit for transistor