JPS60167522A - Semiconductor switch - Google Patents

Abstract

PURPOSE:To secure the actuation of a PNPN switch with high dv/dt tolerance and high sensitivity by using an element of PNPN structure to drive a short circuit protecting TR which gives a short circuit to a P-N junction at one side of the PNPN switch. CONSTITUTION:When the transient voltage having a sudden rise is applied between an anode A and a cathode K, the drive current of a short-circuiting TRQ1 is supplied from a place equivalent to a cathode gate through a PNPN element 2. Thus the TRQ1 is driven with the characteristics similar to the stored residual charge produced by the composite TR effect of a PNPTR and an NPNTR in a PNPN switch 1. Thus the dv/dt effect protecting capacity. While the element 2 is short-circuited by the P-N junction of the anode A and an anode gate GA to a DC action and turned off. Therefore the TRQ1 is not actuated either. Then the gate ignition sensitivity and the minimum holding current of the switch 1 are decided by a resistance R. The resistance of such a level that prevents the misignition due to the leakage current of the switch 1 is needed to the R. Therefore the high ignition sensitivity is obtained from the gate.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to improving the characteristics of a pNpN four-layer structure semiconductor switch, and particularly relates to a semiconductor switch that has a large 4ν/11 withstand capability and operates with high sensitivity. be.

[Background of fading]

A semiconductor switch with a pNpN structure (hereinafter simply referred to as a PNPN switch) includes a PNPN diode with only the anode and cathode electrodes taken out, a terminal thyristor with the cathode gate control terminal or the anode gate control terminal taken out, a cathode gate control terminal and a 7-node gate control terminal. There are four-terminal thyristors, etc., which have both forward and reverse voltages, and are used in various control devices as switching elements that have a high withstand voltage in both forward and reverse directions and have a self-holding function.

However, these PNPN switches have the disadvantage that they will close if a sudden forward voltage is applied between the anode and cathode while the switch is turned off. This phenomenon is dv/l
This is called the effect (or late effect), and various countermeasures have been proposed for this effect. Generally, P
A method is used in which a resistor is connected between the cathode gate GK and the cathode of the NPN switch. However, in order to obtain a high dv/ct withstand capability with this method, it is necessary to connect a low resistance, which inherently has the drawback of poor gate firing sensitivity.

Therefore, ``4'' is a PN with high tolerance and good gate firing sensitivity.
As a means of obtaining a PN switch, as shown in FIG.
A transistor Q is connected between the cathode gate GK and the cathode of the PN switch 1, and the transistor Q1 operates only when a transient voltage is applied, and the anode A of the pNpN switch 1 is connected to short-circuit between the cathode gate GK and the cathode. A circuit in which a capacitive element C is connected between the base of the transistor Q1 and the base of the transistor Q1 is presented in US Pat. No. 5,609,41&. Since this method uses a capacitor as the capacitive element C, it is not very suitable for semiconductor integrated circuits. Moreover, when a circuit having such a configuration is actually integrated into a semiconductor, there are various problems, and the configuration needs to be devised.

First, PNPN switch 1 and dv7. , the operation competition with the protection transistor Q1 takes place, and in particular, recovery from the saturation of the protection transistor Q1 is caused by the PNPN switch 1
This is likely to occur before the reduction in the accumulated charge of ``/ltt'' and the protective effect of ``/ltt'' is lost.

Furthermore, when a transient voltage is repeatedly applied, a difference appears between the discharge of the capacitive element C and the discharge of the junction capacitance of the PNPN switch 1,
The protection transistor may not be driven sufficiently, resulting in a decrease in dv/d and withstand capability. Also”/l
By adding a protection circuit to the PNPN switch, the bidirectional high voltage characteristics inherent to the PNPN switch must not be impaired, and the PNPN
If the protection circuit side does not turn off dv/ct when the switch is normally turned on, it will cause an oscillation problem, so care must be taken.

In order to solve these problems, Ganto Toyama first proposed the circuit shown in Figure 2. i.e., PNPN)
A level shift element connected in series to the emitter and base of transistor Q is connected between the anode and anode gate of PNPN switch 1 to drive protection transistor Q1 as a capacitive element and form a capacitive discharge path. In order to do this, a diode D is connected between the base and emitter of the protection transistor Q.

According to this configuration, it is possible to obtain a PNPN switch that has a large withstand capacity of "/lt" and operates with high sensitivity while maintaining the characteristics of bidirectional high withstand voltage. However, even if JJ is in this configuration, the characteristics of the PNPN switch 1 and transistor Q=-
The problem of competition between dv/lt formed by Qt and the characteristics of the protection circuit remains. Especially PNPN switch 1 is PNP)
Since the transistor and the NpN) rank 4 transistor are integrated, the operation is different from simply connecting individual transistors externally, so there is a difference in the reduction characteristics of accumulated charge, and it is difficult to protect "/lt". There may also be cases where the results are not sufficiently evaluated.

[Purpose of the invention]

An object of the present invention is to provide a semiconductor switch that operates a pNpN switch with high ``/ct'' tolerance and high gate sensitivity. To provide a circuit configuration that is advantageous to competition; (2) Anode gate (GA), cathode gate Gx
(a) By connecting an effect protection circuit to dv/ct, the two-way high withstand voltage characteristics of the pypy switch should not be impaired. (4) To provide a circuit configuration that can be easily integrated into a semiconductor integrated circuit.

[Summary of the invention]

In order to achieve the above object, the present invention uses an element with a PNPN structure to drive a short-circuit protection transistor that shorts one PN junction of a PNPN switch, and the drive circuit is transiently capacitive. In addition, it operates similar to a PNPN switch, and is connected in parallel to the PM junction at the other end of the PNPN switch directly or via a level shift element so that it operates only as a capacitive element in terms of direct current.
This circuit is characterized by a circuit configuration in which the gate portion of the driving pNpN element is connected to the base of the shorting transistor.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a circuit diagram of a first embodiment of a semiconductor switch according to the present invention, where 1 is a PNPN switch, A is an anode,
GA is an anode gate, G is a cathode gate, and K is a cathode. Q is a short-circuit protection transistor that short-circuits the pN junction between the cathode gate Gx and the cathode, 2 is a driving PNPN element that drives the short-circuit transistor, and D
is a discharge diode, and R is a resistance.

According to this circuit configuration, when a rapidly rising transient voltage is applied between the anode A and the cathode, the drive current of the IsM transistor Ql is supplied through the PMPM element 2 from a point corresponding to its cathode gate. As a result, the short-circuit transistor Q is driven with characteristics similar to the accumulated residual charge due to the double gold transistor effect of the PNP transistor and NPN transistor in the pNpN switch 1, and the 'Lv/cLt effect protection ability is obtained. . When PNPN switch 1 is turned on,
Since the charge accumulated in the NP junction of the driving pNpN element 2 is discharged simultaneously with the charge of the pNpN switch 1 in the discharge path passing through the diode D, sufficient dν/11 effect protection ability can be obtained even if repeated transient voltages are applied. .

Next, for DC operation, PNPN elements 2 and 7
・ is the anode A and anode gate of PNPN switch 1)
Since the pN junction of GA is short-circuited and turned off, the short-circuiting transistor Q also does not operate, and the gate firing sensitivity and minimum holding current of the pNpN switch 1 are determined by the resistor R. This resistor R does not need to provide effective protection for a large □, and can be high enough to prevent erroneous firing due to leakage current of the PNPN switch 1, so that high firing sensitivity from the gate can be obtained. Also, bidirectional high voltage characteristics can be easily obtained.

FIG. 4 shows a second embodiment of the semiconductor switch according to the present invention. In particular, a configuration example is shown in which the switching of the operation of the protection circuit is made more reliable during the ON operation of the PMPM switch 1. It shows.

That is, numeral 3 indicates a level shift element, which may be a series connection of n stages of diodes, a series circuit of a diode and a resistor, or, depending on the case, a reverse junction diode with low breakdown voltage. 7. The operation when a transient voltage is applied between the node A and the cathode is the same as the example shown in Figure 3. 8. When the pypu switch 1 is turned on, the PNPN element 2 switches the level shift element 6. 7 nodes through.

Since it is short-circuited at the anode-gate junction, it can be turned off more reliably, and the adverse effects caused by the operation of the transistor Q can be eliminated.

FIG. 5 shows a sixth embodiment of the present invention, and shows an example of a configuration particularly suitable for use as a bidirectional switch by connecting pNpN switches in antiparallel. 1
' is a pNpN switch in which a second P-type region is added in the anode gate region to have the function of a level shift element;
4 is a pNpN for driving the short-circuiting transistor Q.
FIG. 7 shows an example of the structure of an element having a modified NPNPNS layer structure.

Even in such a configuration, the terminal T1#T! When a transient voltage is applied between d and d, the shorting transistor Q1 is driven via the opposite diode D and the NPNPN element
Prevents malfunction due to v/dt application. Figure 6 shows the discharge path when turned on.

Similarly to Fig. 4, diode D, NpNpN element 4 and P
It is formed via a P shadow area for level shifting in the NPN switch 1'. In terms of DC operation, NpNpN j
The series circuit between the middle PNPN part of the LC element 4 and the PN junction formed by the P shadow region in the diode D and the PNPN switch 1' is short-circuited between the anode and the anode gate junction, thereby preserving the effect of "/l". The circuit is turned off.

FIG. 6 shows a fourth embodiment of the present invention, in which an antiparallel-connected PNPN switch 1# is formed between the anode gate regions and an island. 4 is an NPNPN that drives the short-circuiting transistor Q as in FIG.
The S layer structure element 3 is a level shift element similar to the example shown in FIG.

The circuit operation is similar to that shown in FIG. 5, and performs maintenance when /dt is applied, charge discharge when on, and test circuit off operation when the PNPN switch is on DC operation.

In the embodiments described above, an example of a circuit was shown in which the PN junction between the anode and the anode gate was short-circuited, but it is also possible to adopt a configuration in which the cathode and the cathode-gate side are short-circuited in a complementary manner.

For example, FIG. 8 shows a fifth embodiment of the semiconductor switch according to the present invention, which is complementary to the configuration shown in FIG. be.

〔Effect of the invention〕

As explained above, according to the present invention, an error firing prevention circuit based on the effect of v/ct of a pNpN switch uses a PNPN structure element, operates as an active element similar to a pNpN switch when a transient voltage is applied, and operates as a DC Specifically, by configuring the false ignition prevention circuit to be in a cut-off state, even if the characteristics of the PNPN switch vary due to manufacturing variations, etc., protection against the HT effect is effectively achieved, and the gate drive It is possible to provide a circuit configuration that operates with high gate ignition sensitivity, which has the advantage of not impairing the high breakdown voltage characteristics of the pNpN switch, and which is easy to integrate into a semiconductor integrated circuit.

[Brief explanation of drawings]

Figures 1 and 2 show known examples close to the present invention.
. The circuit diagrams of FIGS. 6, 4, 5, 6, and 8 respectively show the first, second, and second circuit diagrams of a semiconductor switch according to the present invention. Third. 4th. A circuit diagram of a fifth embodiment is shown. FIG. 7 shows a cross-sectional view of an NPNPN@ structure element used in the embodiments of FIGS. 5 and 6. FIG. 1.1', 1': pNpN switch 2: PNP
N$3 two-level shift element 4: NpNpN $Qs=Qm; ) transistor D; diode R; resistor A; to anode; cathode GA near-node gate Gx; cathode gate patent attorney Akio Takahashi °12° Almost 1 Figure W82 Ward Figure 3 Iku 4 Figure 5 Seki %6 Figure Ka34.8, 43 Oke/K) ・□ ・ KL GKlp 34 GKI QQz 1q Figure 7

Claims (1)

[Claims] 1. A first PNPN that isometrically forms a 4-layer PNPN structure.
switch and one pN of this first pNpN switch
It is composed of a shorting transistor that shorts the junction and a second PNPN structure element that drives the shorting transistor, and the second PNPN structure element is connected to the first pNPN structure element.
Connected in parallel to the PN junction at the other end of the NpN switch, and the second
A semiconductor switch characterized in that one gate of the pNpN structure element is connected to the base of a shorting transistor. 2. The semiconductor according to claim 1, wherein a level shift element is connected in series to the second PNPN structure element and connected in parallel to the PM junction at the other end of the first PNPN switch. switch. 5 PNPN switches connected in antiparallel and each PNP
One pN junction of the N switch is shorted, and the NPN
N regions at both ends of the PN element are each connected to the 7-node gate of the pNpN switch via a level shift element,
A semiconductor switch characterized in that the intermediate P regions are each connected to a base of a shorting transistor.