Overload protection circuit for switch type transistor

Abstract

The invention relates to an overpower protection circuit of a switching transistor. The 'input electrode' and the 'output electrode' of a protected transistor are connected in a load loop in series. The invention is characterized in that the overpower protection circuit comprises a first input terminal, a second input terminal and a gate circuit of the output terminal; the first input terminal isconnected with a level signal, the second input terminal is connected with the 'input electrode', the output terminal is connected with a 'control electrode'; when the first input terminal and the second input terminal are low level '0', the output terminal is low level '0'; when the first terminal is low level '0' and the second input terminal is high level '1', the output terminal is low level '0'; when the first input terminal is high level '1' and the second input terminal is low level '0', the output terminal is high level '1'; when the first input terminal and the second input terminal are high level '1', the output terminal is low level '0'. The switching protection circuit of the invention is a single gate circuit and field effect transistors are not included in the circuit, so that the power consumption is lower.

Description

technical field [0001] The invention relates to an overload protection circuit for a transistor, in particular to an overload protection circuit when the transistor is used as a switch tube. Background technique [0002] Both the triode and the field effect tube are transistor elements (since both the triode and the field effect tube are composed of NPN and PNP, the direction of the working current is just opposite. The emitter of the NPN transistor, the drain of the NPN field effect transistor, and the source of the PNP field effect transistor are collectively referred to as the "input pole"; the emitter of the NPN transistor, the collector of the PNP transistor, and the source of the NPN field effect transistor The drain of the transistor and the drain of the PNP field effect transistor are collectively referred to as the "output pole"; the base of the triode and the gate of the field effect transistor are collectively referred to as the "control pole"). They are usually ...

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Problems solved by technology

[0002] Both transistors and field effect transistors are transistor components (since both transistors and field effect transistors are composed of NPN and PNP, the direction of working current is just opposite, for the convenience of description, according to In the direction of current inflow and outflow, the collector of the NPN transistor, the emitter of the PNP transistor, the drain of the NPN field effect transistor, and the source of the PNP field effect transistor are collectively referred to as the "input pole"; the emitter of the NPN transistor The collector of the PNP transistor, the source of the NPN field effect transistor and the drain of the PNP field effect transistor are collectively referred to as the "output pole"; the base of the transistor and the gate of the field effect transistor are collectively referred to as the "control pole") , They are usually used as switching devices in the circuit, and their disadvantage is that they are easily damaged once overloaded

However, the above-mentioned circuit has two transistors connected in series in the switching tube circuit, and the entire control circuit will increase additional voltage drop and power loss, making the switching characteristics of the switching transistor worse. protrude

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