Dual-safety voltage difference controllable switch

Abstract

The invention provides a double fuse voltage difference controllable switch which not only controls the switching on / off of a circuit according to the voltage difference of the circuits of both ends of the switch, but also prevents over instantaneous voltage from causing breakdown of a switching tube through a double fuse circuit. The switch comprises a first single MOS power switching tube, a second MOSFET switching tube module, a third switching tube control module and a fourth MOS power switching tube control module, wherein the first single MOS power switching tube is connected with both ends of an external circuit to control the switching on / off of a circuit; the second MOSFET switching tube module realizes shunt and voltage limit of the first single MOS power switching tube, therebyensuring the normal operation of the tube and preventing the breakdown of the tube; through judging the voltage difference of both ends of an external circuit and limiting amplitude, the third switching tube control module controls the operation of the second MOSFET switching tube module, thereby forming second protection of the switch; moreover, the fourth MOS power switching tube control modulecontrols the first single MOS power switching tube M.

Description

Technical field [0001] The present invention relates to switches for MOS integrated circuits. In particular, it relates to a MOS integrated circuit switch capable of using the voltage difference of external circuits on both sides of the switch to perform closing and breaking control according to set conditions, and capable of performing double-layer protection on the switch. Background technique [0002] As we all know, MOSFET switch tubes are widely used in various integrated circuits, and the switching on or off of the switch tube is controlled by the positive power supply and negative power supply of the integrated circuit connected to the gate of the switch tube. For a P-type MOSFET switch tube, it has four ports of source, drain, gate and substrate. Usually integrated circuits are made on P-type silicon wafers, and its substrate is P-type silicon wafers. P-type MOSFETs The tube substrate of the switch tube is formed by the N well region, which is connected to the highe...

AI Technical Summary

Problems solved by technology

[0003] There is such an application that at some point, the positive power supply (or negative power supply) on the integrated circuit chip is lower (or higher) than the voltage of the external input or output interface, so that one of the voltages at both ends of the MOSFET switch tube is high In the positive power supply or lower than the negative power supply, the tube substrate of the P-type MOSFET switch tube is not connected to the highest potential of the four ports of the switch tube, and the tube substrate of the N-type MOSFET switch tube is not connected to the four ports of the switch tube At the lowest potential of , the MOSFET switch tube connected according to the above method will not work normally because it cannot be turned off

[0004] At the same time, when the voltage difference between the external input and output interfaces is too large, especially the instantaneous excess charge impact exceeds the withstand capacity of the MOSFET switch tube, causing the MOSFET switch tube to be broken down, which directly leads to the failure of the integrated circuit to return to meet the design requirements. normal working condition

[0005] Even if the voltage difference between the external input and output ports does not reach the voltage value that causes the MOSFET switch tube to be broken down, long-term operation with a large voltage difference will have a great impact on the service life and parameters of the switching device. Influence, this is a problem that must be considered and urgently needed to be solved in integrated circuits

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