JPS615619A - Transistor circuit - Google Patents

Abstract

PURPOSE:To reduce breakdowns and deterioration due to malfunction of a transistor (TR) by providing a resistance between the emitter and collector of a TR in a bipolar driving circuit. CONSTITUTION:Resistances 13-16 are connected between collectors and emitters of TRs 5-8 respectively. Resistance values of the resistances 13 and 15 and resistance values of the resistances 14 and 16 are set equal. When all of the TRs 5-8 are turned off with control signals from input terminals 1-4, the voltage at a point C is partial voltage of a power source 18 depending upon the resistance values of the resistances 13 and 14 and the voltage at a point D is a partial voltage of the power source 18 based upon the resistance values of the resistances 15 and 16. Consequently, the potential difference between the points C and D is eliminated and no load current I flows. Consequently, breakdowns and deterioration due to malfunction of a TR are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transistor circuit comprising a bipolar drive circuit.

(Conventional technology) FIG. 3 is a circuit diagram of a conventional bipolar drive circuit.

In the same figure, 31 to 34 are input terminals to which a control signal for turning the transistors 35 to 38 into 0N10FF is input;
5 to 38 are transistors that perform switching operations; 3;
9 is a load, and 40 is a power supply. The positive side of the power supply 40 is connected to the emitters of transistors 35 and 37, and the negative side is connected to the emitters of transistors 38 and 38. Further, the collector of the transistor 35 is connected to the transistor 3
6, and the collector of transistor 37 is connected to the collector of transistor 38. The common connection between the collectors of transistors 35 and 3e and transistor 3? , 3B, a load 39 is inserted and connected between the common connection portion of each collector.

Next, to explain the operation, control signals are input from the input terminals 31 to 34, and the transistors 35 and 38 are turned off.
N state, when transistors 38 and 37 are OFF state,
Load power I, I flows through the load 38, transistors 35 and 3B are in the OFF state, and transistors 313 and 3
? When is in the ON state, a load current I3'l flows through the load 39 in the opposite direction to the load current 1.4. In such a bipolar drive circuit, transistors 35 to 38
Depending on the state, a load current can be passed through the load 38 in the forward or reverse direction.

However, if the control signals input to the input terminals 31 to 34 are disturbed, that is, if the transistors 35 and 3Ei are turned on at the same time, the transistors 35 and 38
Due to the large current flowing through the transistor, the transistor is destroyed and deteriorated.
Further, there is a problem in that it becomes a source of noise, causes malfunction of other circuit 1 equipment, and further consumes unnecessary power. Further, the same applies when the transistors 37 and 38 are turned on at the same time. Generally, when a large load current is desired, Darlington transistors are often used for the transistors 35-38. In this case, since the current amplification factor of the Darlington transistor is large, the transistors 35 to 38 are turned on regardless of the control signals input to the input terminals 31 to 34. This will be explained based on the drawings.

FIG. 4 is a circuit diagram of a bipolar drive circuit using one Darlington transistor. In the figure, 41 is an input terminal into which a control signal for turning the Darlington transistor 42 into 0N10FF is input, 42 is a Darlington transistor, 43 is a capacitor equivalently representing the stray capacitance between the base and collector of the Darlington transistor 42, 44 is a load, 45 is a switch, and 4B is a power supply. The base of the Darlington transistor 42 is connected to the input terminal 41, the collector is connected to one end of the load 44, and the emitter is grounded.

The other end of the load 44 is connected to one end of a switch 45, the other end of the switch 45 is connected to the positive side of the power source 4B, and the negative side of the power source 48 is grounded. Here, the capacitance of the capacitor 43, that is, the stray capacitance between the base and collector of the Darlington transistor 42 is Co&+the base Φ collector voltage of the Darlington transistor 42 is assumed to be . Now, if the switch 45 is closed, the problem to be solved by the invention is that the Darlington transistor 42 has a large current amplification factor hfa, so even if the current Ib is small, the collector current Ie = h chi tomoe * i6 will flow. become.

When the circuit in Figure 2 is replaced with the circuit in Figure 1.

The switch 45 is connected to the transistor 35 (or transistor 3
7), Darlington transistor 42 is transistor 3
e (or transistor 38) and load 44 are not supported. When the transistor 35 is turned on, a small current iL flows for a short time in the stray capacitance between the base and collector of the transistor 3B.
A large current flows through the transistor 35 or transistor 3B, causing destruction or deterioration of the transistor 35 or the transistor 3B, causing noise generation and malfunction of other circuits.

The present invention is intended to solve these problems, and is a transistor that can reduce destruction and deterioration due to transistor malfunction, reduce generated noise, and prevent malfunction of other circuit devices. The purpose is to provide circuits.

(Means for solving the problem) The first and third collector-emitter circuits are connected in series.
, second and fourth transistors each having a collector-emitter circuit connected in series, a connection point between the first and third transistors, and a connection point between the second and fourth transistors. and a resistor is connected between the emitter and collector of each of the first to fourth transistors. The resistance values of the respective resistors connected between the emitter and the collector of the second transistor are made equal, and the resistance value of each resistor connected between the emitter and the collector of the third transistor is made equal. Emitter of the fourth transistor
Make the resistance values of each resistor connected between the collectors equal.

(Function) The potential difference between the two connection points becomes a voltage division of the power supply by the resistor connected to each connection point, and the voltage of the four transistors is 0N10.
Depending on the FF state, the current direction flowing to the load is controlled to prevent the collector current of the five transistors.

(Embodiment) FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the same figure, 1 to 4 indicate transistors 5 to 8 at 0N10F.
Input terminals to which the control signal for F is input; 5 to 8 are transistors that perform switching operations; 8 to 12 are load 1
7 is a diode that protects the transistor from breakdown due to the back electromotive force caused by the coil; 13 to 16 are resistors; 17 is a load; and 18 is a power supply. Input terminals 1 to 4 are transistors 5
~8 bases and are connected to each other. The positive side of the power supply 18 is the emitter of the transistor 1, the anode of the diode 8,
One end of resistor 13.

One end of the resistor 15, the anode of the diode 1, and the emitter of the transistor 7 are commonly connected, and the negative terminal is connected to the transistor 8.
emitter of, cathode of diode lo.

It is commonly connected to one end of the resistor 14, one end of the resistor 1B, the cathode of the diode 12, and the emitter of the transistor 8. Further, one end of the load 17 is the collector of the transistor 5,
collector of transistor 8, cathode of diode 8,
Anode of diode 10, other end of resistor 13, resistor 14
Connect in common with the other end, and measure this connection point as 0 point. The other end is the collector of transistor 7, the collector of transistor 8, the cathode of diode 11, and the 7 node 1 of diode 12. Commonly connect the other end of the resistor 15 and the other end of the resistor 1B,
Let this connection point be point D. Here, the resistance values of resistors 13.15 and 14.15 are equal. The resistance values of IEI are equal. Further, the load 17 is a reactive load. Now, assume that the direction of the load current flowing from point 0 to point D via load 17 is positive.

Next, the operation will be explained. The transistor 5.8 is turned on by the control signal input from the input terminals 1 and 4,
When the transistor 8.7 is turned off by the control signal input from the input terminal 2.3, the load current I flows from the collector of the transistor 6 to the collector of the transistor 8 via the load 17. The direction will be Conversely, the control signal input from the input terminal 1.4 turns the transistor 5.8 off, and the control signal input from the input terminal 2.3 turns the transistor 6 off.
．． 7 is in the ON state, the load current I flows from the collector of the transistor 7 to the collector of the transistor 8 via the load 17, and becomes negative in the load 17.

In addition, when all of the transistors 5 to 8 are turned off by the control signals input from the input terminals 1 to 4, the voltage at the 0 point is the divided voltage of the power supply 18 by the resistance values of the resistors 13 and 14. , since the voltage at point D is a divided voltage of the power supply 18 based on the resistance values of the resistor 15 and the resistor 16, there is no potential difference between the 0 point and the point D, and the load current I does not flow. Resistance 13~1
B can also be built into a Darlington transistor.

FIG. 2 is a diagram showing the experimental results of this example.

When resistors 13 to 1B in FIG. 1 and resistors 27 of Ω are used, the potential difference between point 0 and point D in FIG. 1 is 1/2 of the voltage of power supply 1B. Therefore, the minute current flowing to the base becomes 1/2. Although the collector current of a transistor is the product of a minute current and a current amplification factor, it is obvious that the current amplification factor is different when the resistors 13 to 16 are present and when they are not, and therefore cannot be compared directly.

Figure 2 shows the base minute current waveform. Waveform a is the case when resistors 13 to 18 in Figure 1 are not present, and waveform A is the waveform when resistors 13 to 1B and 27 in Figure 1 are used. be. As can be seen from the figure, in waveform a, the collector current of transistor 6 was flowing at 1.2 [A] at the moment when transistor 5 in Fig. 1 was turned on, but in waveform a, it was 0.35 [A].
It decreased to [A]. In addition, in the experiment that obtained the experimental results shown in Fig. 2, the circuit shown in Fig. 1 was used. 2SD788 (Newly manufactured by Hitachi) was used as the transistor 6.8, and the power supply 18 was set to 80 [V].

(Effects of the Invention) As described above, according to the present invention, by providing a resistor between the emitter and collector of the transistor, destruction and deterioration due to malfunction of the transistor can be reduced.
It is possible to provide a transistor circuit that can reduce generated noise and prevent malfunctions of other circuit 2 devices.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing experimental results of this embodiment, Fig. 3 is a circuit diagram of a conventional bipolar drive circuit, and Fig. 4 is a Darlington transistor 1.
FIG. 1-4.31 to 34.41---one input terminal, 5 to 8.
35-38--1-) transistor,' 9-12---
-Diode, 13~to---one resistor, 17.39.44---
-One load, 18, 40.46---Power supply, 45---
-Switch. Patent application Hitoki Electric Industry Co., Ltd. Patent application agent Megumi Yamaki 1 book 7 figures Book 2 figures + 5 Shinjisku Busy ONg! t

Claims (1)

[Claims] The first and third collector-emitter circuits are connected in series.
a transistor, second and fourth transistors having collector-emitter circuits connected in series, and a load inserted between the connection point of the first and third transistors and the connection point of the second and fourth transistors. a bipolar drive circuit in which a control signal is inputted to the base of each transistor, wherein a resistor is connected between the emitter and collector of each of the first to fourth transistors;
The resistance value of each resistor connected between the emitter and collector of the second transistor is equal, and the resistance value of each resistor connected between the emitter and collector of the third and fourth transistors is equal. transistor circuit.