power switch circuit

Abstract

The invention provides a power switch circuit, which includes a first transistor, a second transistor and a control circuit. The first terminal of the first transistor serves as the input terminal of the power switch circuit. The second end of the first transistor is coupled to the node. The control terminal of the first transistor receives the first control voltage. The first terminal of the second transistor serves as the output terminal of the power switch circuit. The second end of the second transistor is coupled to the node. The control terminal of the second transistor receives the second control voltage. The control circuit detects the voltage of the node to determine the type of series connection between the first transistor and the second transistor, and generates a first control voltage and a second control voltage according to the type of series connection, so as to fully turn on the first transistor and the second transistor. After one of the two transistors starts to control the conduction state of the other of the first transistor and the second transistor.

Description

technical field [0001] The invention relates to a power supply circuit, in particular to a back-to-back power switch circuit capable of preventing failure of soft start. Background technique [0002] In circuit design using transistors as power switches, in order to prevent the parasitic diodes inside the transistors (i.e., body diodes) from being turned on and cause the power switches not to be completely turned off, designers usually use two transistors connected in series back-to-back To realize the power switch. However, since the two transistors may have different threshold voltages, the two transistors may not switch from the off state to the on state simultaneously when the power switch is soft-started. If the transition time interval of one transistor from the off state to the on state overlaps only partially with the transition time interval of the other transistor from the off state to the on state, the overall equivalent resistance of the two transistors will be ...

AI Technical Summary

Problems solved by technology

However, since the two transistors may have different threshold voltages, the two transistors may not transition from the off state to the on state simultaneously when the power switch is soft-started

If the transition time interval of one transistor from the off state to the on state overlaps only partially with the transition time interval of the other transistor from the off state to the on state, the overall equivalent resistance of the two transistors will be The change of the value is not smooth, so that the power switch will generate inrush current during the startup process and cause the soft start to fail

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