High side power MOSFET switch tube group having reverse current blocking function

Abstract

The invention relates to a high-power MOSFET switch tube set with a structure for blocking reverse current. The high-power MOSFET switch tube set comprises a first power MOSFET tube, an input voltage end, an output voltage end and a grid electrode drive end; the switch tube set further comprises a second power MOSFET tube, wherein a grid electrode of the first power MOSFET tube is connected with a grid electrode of the second power MOSFET tube; a substrate of the first power MOSFET tube is connected with a substrate of the second power MOSFET tube; a source electrode and the substrate of the second power MOSFET tube are connected; and a source electrode of the first power MOSFET tube is connected with a drain electrode of the second power MOSFET tube.

Description

technical field [0001] The invention relates to a high-side power MOSFET switch tube group, in particular to a high-side power MOSFET switch tube group with the function of preventing reverse current. Background technique [0002] In the circuit design of a battery charger chip or a USB power distributed switch, when the switching device is turned off, since the body diode between the source and the substrate is shorted, when the output V out greater than V in , there is a V out terminal returns to V through the high-side power transistor in The problem of the reverse current at the terminal, the reverse current will cause leakage of the charger, damage to the input power supply, etc., so measures need to be taken to prevent reverse current. For high-side power MOSFET switches without preventive measures, such as figure 1 As shown, in order to reduce the bias effect of the substrate and reduce the on-resistance of the high-side power tube, the source of the MOSFET is con...

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Problems solved by technology

[0003] For the above situation, if figure 2 As shown, a known way to prevent reverse current is to connect the substrate to ground, thus, the body diode between the source and the substrate will prevent the reverse current, but the substrate and ground are connected in normal operation. When the substrate has a body bias effect, which increases the threshold voltage of the MOSFET tube, it greatly affects the key parameter of the USB power distributed switch or charger chip, that is, the on-resistance R on increases, reducing the efficiency of the voltage conversion device

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