JPH03113913A - Semiconductor switch - Google Patents

Abstract

PURPOSE:To surely detect on/off of a main current by providing a 2nd anode terminal for detecting the on/off state of the main current to a main current switch circuit. CONSTITUTION:The on-control is implemented by supplying an on-driving current from a gate G, a 4-terminal PNPN switch 2 is turned on, then transistors(TRs) Q5, Q6 are turned on and a load current flows from a 1st anode A to a cathode K. Moreover, since a TR Q12 is simultaneously turned on, an on-detection current flows from a 2nd anode A2 to the cathode K. Then the off-control is implemented by supplying an off-driving current from an off-control input terminal B to interrupt a load current flowing to the anode A1 to the cathode K. Thus, the detection characteristic is ensured and the occupied area for the detection element is decreased, then high circuit integration is attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a semiconductor switch including a PNPN switch, and in particular, a semiconductor switch that can accurately detect the on/off state of the main current from the outside and is easy to integrate into semiconductors. This invention relates to semiconductor switches.

[Conventional technology]

Generally, a PNPN switch as a semiconductor switch is
Compared to transistor switches, they have advantages such as high bidirectional breakdown voltage, low on-resistance, and low on-voltage even when a large current is applied. but,
At the same time, since it has a self-holding function, when used as an on/off switch, it has the disadvantage that off control is relatively distant.

To turn off a PNPN switch without changing the load current, there are two methods: transiently shorting the gate and cathode to temporarily increase the holding current, making it impossible to hold the load current, and applying a reverse current to the gate. There are different ways to turn it off, which can be used depending on the current cutting ability and external circuit conditions.

Now, since the on/off switch constructed using these methods has a self-holding function, it may be necessary to detect the on/off state of the switch. PNPN
The switch enters the off state with a delay of the turn-off time caused by the charge accumulation time from the time of off-drive, but
Depending on the application of the switch, this delay time may cause problems with external control. For example, when a current selection switch is configured with two on/off switches using PNPN switches, first, one switch is driven off in a pulsed manner, and then the other switch is driven on in a pulsed manner to control the load current. When trying to switch, there are cases where the switch that receives the OFF drive does not completely turn off, and the other switch turns on, causing both switches to remain on at the same time. This is a phenomenon caused by the self-holding function of the PNPN switch, which continues to operate as long as the main electrodes are externally conductive even without gate control, and the fact that the turn-off time is generally longer than the turn-on time. be. In order to prevent such malfunctions, a method is required to detect at what point the load current of the switch is turned off.

Figure 1 shows the circuit configuration of an on/off switch with an off detection function. Control is achieved by applying drive currents to the gate G and OFF control input terminal B, respectively, and as a result, the load current determined by the load resistor R2 of the external circuit and the power source 1 can be turned on and off. here,
The resistor R1 prevents the PNPN switch 1 from malfunctioning due to the dv/dt effect, and the gate firing sensitivity of the PNPN switch 1 is determined by this resistor R1.

Further, the transistor Q3 is temporarily short-circuited between the gate G and cathode of the PNPN switch 1.

This increases the minimum holding current value of the PNPN switch 1 and shifts it to the off state.

Furthermore, the transistor Q4 is for detecting the on/off state of the PNPN switch 1.

That is, transistor Q2. Since the base and emitter of transistor Q4 are connected in common, transistors Q2. Q4 has substantially the same base bias condition, and their respective collector currents also become substantially equal. Here, since the collector current of transistor Q2 is a part of the anode current of PNPN switch 1,
If the collector current of transistor Q4 is monitored, PNP
This means that the on/off state of the N switch 1 can be detected. FIG. 2 schematically shows the above operating waveforms, and shows I(
+ indicates the on-related current, 3 indicates the off-current, 2 indicates the anode current, and 1 indicates the collector current of the transistor Q4. As is clear from FIG. 2, the on/off information of the anode current of the PNPN switch 1 can be detected from the presence or absence of the collector current IC of the transistor Q4, that is, from the voltage drop across the resistor R3 in FIG.

[Problems to be Solved by the Invention] However, the circuit configuration shown in FIG. 1 has the following drawbacks. The first drawback is that □off detection is not temporally accurate. Normally, the PNPN switch 1 and the transistor Q4 are separate devices, so their turn-off times differ because they have different sizes and shapes, and because the external load conditions cannot always be the same. Furthermore, since the turn-off time of the PNPN switch 1 tends to be the sum of the turn-off times of the component transistors Q layer and Q2, accurate off detection cannot be performed with the transistor Q4. That is, when driven off in FIG.
Transistor Q2. Since the base and emitter of Q4 are simultaneously short-circuited by the transistor Q3, the transistor Q4 quickly turns off, but the PNP transistor Q1 turns off from that point on.

As a result, t4 in FIG. PNP as shown as ts
Since the off detection is performed before the N switch 1 is completely off, the purpose is not fully achieved.

The second drawback is that the number of elements increases because the transistor Q4 is added for off-state inspection. this is.

When considering semiconductor integrated circuits, the area occupied by the element increases, which is undesirable from an economical point of view.

As described above, the semiconductor switches according to the prior art have disadvantages in that the off-detection characteristics are insufficient and the device occupies a large area.

An object of the present invention is to obtain a semiconductor switch which has accurate main current on/off detection characteristics, has a small element occupation area, and is suitable for integration.

[Means to solve the problem]

For this purpose, the present invention provides a main current switch circuit with a second anode terminal for detecting the on/off state of the main current, so that it can accurately detect the on/off state of the main current. It is characterized by

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 3 is a circuit configuration diagram showing an example of a semiconductor switch that is an improvement on the conventional semiconductor switch described above.
Q12. Q2 is two PNP transistors and one NPN transistor that constitute the 4-terminal PNPN switch 2, Q3 is an NPN transistor for turn-off, R1 is a resistor for preventing malfunction due to dv/dt effect, V layer, R2
are the load power supply and resistance, respectively, and V2. R3 is a power supply and a resistor for on/off detection, respectively. Also, A1 is the first
, A2 is the second anode terminal, K is the cathode terminal, G is the gate terminal, and B is the off control input terminal. In this example, 1-transistor Ql layer, Q
12. The main current switch circuit of the semiconductor switch is configured by the 4-terminal PNPN switch 2 consisting of Q2. 9. NPN
The transistor Q3 and the resistor R1 constitute a switch circuit for turning off the semiconductor switch. In the circuit configuration shown in Fig. 3, on control is achieved by supplying an off drive current from the gate G, and the PNPN switch composed of the Ql layer and Q2 is turned on, which is determined by the external circuit's power supply V1 and resistor R2. Load current flows from anode A1 to the cathode. Also, at the same time, 012. The PNPN switch constituted by Q2 is also turned on, and an on-detection current determined by the external circuit power supply (2) and resistor R3 flows from the anode A2 to the cathode. Next, off control is performed by injecting an off drive current from off control input terminal B, transistor Q3 is turned on, and the PNPN
By shorting between the gate G and cathode of switch 2, that is, between the base and emitter of transistor Q2, the holding current value of the PNPN switch is increased, and the anode A
The load current flowing from 1 to the cathode K is turned off. At the same time, the on-detection current flowing from the anode A2 toward the cathode K is also turned off.

Now, in the circuit configuration shown in Figure 3, the main current is on/off.
Off detection is performed using a PNP transistor Qll through which the main current flows and a PNP transistor Q whose base and collector are commonly connected.
12 with or without emitter current. In the turn-off operation of the PNPN switch, first, the NPN transistor Q2 is turned off by shorting its base and emitter by the transistor Q3, and then the PNP transistors Q1 and Q12 are turned off at the same time.
The times during which the inflow currents from the anodes A and A2 are turned off are approximately the same. Similarly, regarding the turn-on operation of the PNPN switch, the NPN transistor Q2
After turning on, the PNP transistor Ql layer, Q
12 turn on at the same time. As a result, the presence or absence of an inflow current from the second anode A2 indicates the on/off state of the main current at an appropriate time, making it possible to obtain a semiconductor switch with accurate on/off detection characteristics. be.

Furthermore, the four-terminal PNPN switch 2 shown in FIG. 3 can be a device of integral construction. FIG. 4 shows the cross-sectional structure of this four-terminal PNPN switch 2, where 10 is an N-type semiconductor substrate, 11°, 12, 13 is a P-swelled diffusion layer, 14 is an N-swelled diffusion layer, and 15 is an N-swelled diffusion layer. Oxide film, 16a
, 16b, 16c, and 16d respectively indicate metal wiring layers. The first anode terminal A1 of the four-terminal PNPN switch 2 passes through the P-type wave dispersion layer 11 to the metal wiring layer 16a.
Similarly, the second anode terminal A2. The gate terminal G and cathode terminal each have P type diffusion/913.
P-type diffusion M12. Metal wiring layer 1 via N expansion diffusion layer 14
Take out from 6b, 16c, 16d.

Since the four-terminal PNPN switch 2 can be formed into an integral structure as shown in FIG. 4, the circuit shown in FIG. 3 can occupy a small area. Furthermore, according to prototype experiments conducted by the present inventors, the operation of the circuit shown in FIG.
After ll turns off, transistor Q12 turns off,
It was found that there was sufficient time to detect the main current off. That is, when the circuit shown in FIG. 3 is integrated into a semiconductor, an economical design with a high degree of integration can be achieved, and a semiconductor switch can be obtained that can accurately detect on/off of the main current.

FIG. 5 is a circuit configuration diagram showing an embodiment of the semiconductor switch according to the present invention, in which the circuit configuration shown in FIG. 3 includes a current shunting transistor Q5. By adding Q6, the current cutting ability as a semiconductor switch is further improved.

That is, in this embodiment, the transistor Q11゜Ql2
．． A four-terminal PNPN switch 2 consisting of Q2 and first and second transistors Q5 for current shunting.

Q6 constitutes the main current switch circuit of the semiconductor switch. In FIG. 5, the same symbols are used for the same parts as in FIG. 3, but the power supply V layer, V2, and resistors R2, R3 of the external circuit shown in FIG. 3 are omitted. In this circuit configuration as well, on-control is achieved by supplying an on-drive current from the gate G, first turning on the four-terminal PNPN switch 2, then turning on the transistor Q5. Q6 is turned on, and a load current flows from the first anode A1 to the cathode. Furthermore, since the transistor Q12 is also in the on state at the same time, the on-detection current flows from the second anode A2 to the cathode.

Next, off control is also performed by injecting an on drive current from off control input terminal B, first transistor Q3 is turned on, 4-terminal PNPN switch 2 is turned off,
Next, a current shunting transistor Q5. Q6 turns off, cutting off the load current flowing from anode A1 to the cathode. At the same time, the on-detection current flowing from the second anode A2 toward the cathode K is also turned off.

In this embodiment, the load current is connected to the PNPN switch 2 and the transistor Q5. Since the configuration is to separate the flow into Q6,
A semiconductor switch having a greater current cutting ability than the semiconductor switch shown in FIG. 3 can be obtained. Also, Figures 3 and 4
As explained in the figure, the four-terminal PNPN switch 2 can be formed into an integral structure, so that the device occupies a small area.

〔Effect of the invention〕

As described above in detail, the present invention detects the on/off of the main current from the second anode terminal of the main current switch circuit, thereby making the detection characteristics accurate and Since the area occupied by the element can be reduced, high integration is possible, and a semiconductor switch with excellent characteristics and economical efficiency can be provided.

[Brief explanation of drawings]

Figure 1 is a circuit configuration diagram of a conventional semiconductor switch, Figure 2 is an operating waveform diagram of the circuit configuration in Figure 1, and Figure 3 is a circuit showing an example of a semiconductor switch that is an improvement on the conventional semiconductor switch. FIG. 4 is a structural sectional view of the four-terminal NPNP switch shown in FIG. 3, and FIG. 5 is a circuit diagram showing an embodiment of the semiconductor switch according to the present invention. 1... PNPN switch, 2... 4-terminal PNPN switch, Q layer, Q2. Ql layer, Ql2... PNPN switch configuration transistor, Q3. Q5. Q6...transistor, A1...first
anode terminal, A2... second anode terminal, K... cathode terminal, G... gate terminal, B...
...Off control input terminal. man j figure

Claims (1)

[Claims] 1. A first anode terminal for a main electrode, a cathode terminal,
A semiconductor switch comprising: a main current switch circuit having a gate terminal for control and a second anode terminal for current detection; and a turn-off switch circuit connected between the gate and cathode terminals of the main current switch circuit. The main current switch circuit includes a PNPN switch and the PNPN switch.
It consists of a current detection transistor whose base and collector are connected to parts of the N and P layers of the NPN switch with the same polarity, excluding the main electrode terminal, respectively, and first and second current shunting transistors. , one main electrode terminal of the PNPN switch is connected to the emitter of the first current shunting transistor, the other main electrode terminal of the PNPN switch is connected to the base of the second current shunting transistor, and the first The base and collector of the current shunting transistor are respectively connected to the collector and emitter of the second current shunting transistor, and the emitter and collector of the first current shunting transistor are respectively connected to the main current switching circuit. 1st for electrode
The anode terminal and cathode terminal of the PNPN switch, the gate terminal of the PNPN switch, and the emitter of the current detection transistor are configured as a gate terminal for controlling the main current switch circuit and a second anode terminal for current detection, respectively, A semiconductor switch characterized in that the on/off state of the inflow current of the first anode terminal is detected by the inflow current of the second anode terminal.