JPH069332B2 - Semiconductor switch - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor switch, and more particularly to a semiconductor switch using a PNPN element suitable for use at a floating potential.

[Background of the Invention]

When passing an AC signal such as a ringer signal of a telephone through a semiconductor switch using a PNPN element, Japanese Patent Publication No.
As shown in Japanese Patent Laid-Open No. -50673, if both the P-type gate and the N-type gate are used, it is possible to handle a large voltage amplitude signal by low voltage control. However, in the arrangement shown in this prior art, the current crossing through the PNPN element must be relied on to zero cross that current. Moreover, since the gate drive current is superimposed on the main current, this drive current may be an obstacle.

Generally, in order to turn on the PNPN element, a gate drive current exceeding the gate firing sensitivity is required. Therefore, when the existence of the gate drive current becomes a hindrance as described above and the gate drive current needs to be reduced, the ignition sensitivity of the PNPN element must be further increased. On the other hand, increasing the sensitivity of the PNPN element lowers the malfunction resistance against external noise and fluctuations in ambient temperature, and malfunctions easily due to external noise and fluctuations in ambient temperature, making it unusable as a semiconductor switch.

[Object of the Invention]

According to the present invention, in order to achieve both of the above contradictory characteristics in a semiconductor switch using a PNPN element, forced disconnection is possible even at an arbitrary potential of the PNPN element, and control is possible even if the gate drive current is extremely small. The purpose is to provide a semiconductor switch that does not malfunction.

[Outline of Invention]

Therefore, in the semiconductor switch as described above, if the gate drive circuit and the disconnection circuit are controlled so as to operate exclusively, the disconnection circuit is operating except when the PNPN element is on-driven, so that the malfunction tolerance is increased. Is possible
It has been thought that the contradictory characteristics of high sensitivity and high malfunction tolerance of the PNPN element can be achieved at the same time.

In order to achieve the former object, the present invention provides a semiconductor switch composed of two PNPN type elements connected in anti-parallel to each other, and a gate drive circuit for driving P-type and N-type gates of the element. A current supply type disconnecting circuit for supplying a current to the N-type gate to disconnect the element, and a current absorption type circuit for absorbing a current from the P-type gate to disconnect the element. And the cutting circuit is controlled so that the gate drive circuit and the cutting circuit operate exclusively in order to achieve the latter of the above objects.

Example of Invention

FIG. 1 shows a first embodiment of the present invention, in which a current supply type disconnecting circuit 2 is connected to an N-type gate of a PNPN element 1 connected in antiparallel and a current absorption type is connected to a P-type gate. The disconnection circuit 3 is connected. The gate drive circuit 4 is also connected to both gates, and the disconnection circuits 2 and 3 and the drive circuit 4 are connected.
And are controlled to operate exclusively. According to this configuration, when the PNPN element 1 is not turned on, it is toughly cut by the cutting circuits 2 and 3, so there is no fear of false firing due to the du / dt effect peculiar to the PNPN element. The current supply type disconnection circuit 2 operates when the potential of the PNPN element 1 is negative, and the current absorption type disconnection circuit 3 operates.
When the potential of the PNPN element 1 becomes floating, malfunction can be prevented regardless of the potential when the potential of the PNPN element 1 becomes floating. On the other hand, when the PNPN element 1 is turned on, the disconnection circuits 2 and 3 are both turned on. Therefore, the gate drive circuit 4 can be easily turned on by a very small constant current drive or pulse drive via a capacitor.

FIG. 2 shows a second embodiment of the present invention, which is PNPN.
The element 1 is connected in two stages in series and is connected in anti-parallel, and the current supply type disconnection circuit 2 and the current absorption type disconnection circuit 3 are connected in series in two stages, respectively. Connected to the P-type gate and the P-type gate. By doing so, a high breakdown voltage junction can be interposed between the main terminals A and B of the switch and the disconnection circuit, and it is possible to handle an amplitude signal having a higher voltage than that of FIG. The gate drive circuit 4 is composed of a capacitor and can be turned on by pulse drive. The gate drive may be a minute constant current drive as in FIG. The operation is the same as in FIG.

FIG. 3 shows an embodiment in which the configuration of FIG. 2 is further simplified. The P-type and N-type inner gates of the PNPN element 1 are commonly connected to each other, and the cutting circuits 2 and 3 and the gate drive circuit 4 are connected.
The cutting circuit and the gate driving circuit are halved by providing each of them with one. The operation is the first
This is similar to the case of FIG.

〔The invention's effect〕

As described above, according to the present invention, in a semiconductor switch using a PNPN element as a main switch, a large-amplitude floating signal can be handled, and forced disconnection of the switch can be controlled with a low voltage regardless of the amplitude of the floating signal. Moreover, there is an effect that the gate can be driven with a minute current.

Further, according to the present invention, since a high malfunction tolerance can be obtained, it is possible to provide a semiconductor switch that is less likely to malfunction due to external noise and fluctuations in ambient temperature.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing a second embodiment of the present invention, and FIG. 3 is a diagram showing a third embodiment of the present invention. 1 ... PNPN type element, 2 ... Current supply type cutting circuit, 3
… Current absorption type cutting circuit, 4… Gate drive circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junjiro Kitano 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Ltd. Totsuka Plant (72) Inventor Yasunori Inabe 1839, Ono, Atsugi, Kanagawa Nippon Telegraph and Telephone Corporation Inside the Atsugi Telecommunications Research Institute (72) Inventor Masaaki Tanabe 1839 Ono, Atsugi City, Kanagawa Prefecture Inside the Atsugi Telecommunications Research Institute, Nippon Telegraph and Telephone Corporation (56) Reference JP-A-58-7924 (JP, A) JP A 58-7923 (JP, A)

Claims (2)

[Claims] 1. Two PNPN type elements connected in anti-parallel to each other, a gate drive circuit for driving P-type and N-type gates of the elements, and a current supply to the N-type gates to supply the elements. A cutting circuit of a current supply type for cutting off the device, and a cutting circuit of a current absorption type for cutting off the element by absorbing a current from the P-type gate. A semiconductor switch characterized in that the cutting circuit is controlled to operate exclusively. 2. Four PNPNs in which a cathode of a PNPN type device having a P-type gate and an anode of a PNPN type device having an N-type gate are connected in series, and those connected in series are connected in antiparallel with each other. Element, a gate drive circuit for driving P-type and N-type gates of the element, and a current to the N-type gate on the side of the connection point between the series-connected elements to disconnect the element. And a current absorption type disconnection circuit for absorbing a current from the P-type gate on the connection point side to bring the element into a disconnected state, the gate drive circuit and the disconnection circuit A semiconductor switch characterized in that the circuit is controlled to operate exclusively.