Voltage detecting circuit

摘要

In a voltage detecting circuit, a transistor Mp1 is configured as a P-type MOSFET, and includes a source connected with an input terminal Tvin, a gate connected with a ground voltage terminal Tgnd and a drain connected with an output terminal Tvout. A transistor Mp2 is configured as a P-type MOSFET, and includes a gate and a source connected with the output terminal Tvout and a drain connected with the ground terminal Tgnd. Gate width W1 and gate length L1 of the transistor Mp1 and gate width W2 and gate length L2 of the transistor Mp2 are adjusted so that source-drain current Ip2 flowing between the source and the drain of the transistor Mp2 becomes equal to source-drain current Ip1 flowing between the source and the drain of the transistor Mp2 when the voltage applied to the input terminal Tvin is set to be preset trigger voltage V Trigger . This configuration accomplishes detecting that the input voltage Vin exceeds the trigger voltage V Trigger with simple configuration.