System and method of clamping a charger input when no charger is detected

摘要

A system and method is related to charger systems that require fault protection at an input terminal. A clamp circuit is activated when the power source is detected as disconnected from the system. The clamp circuit operates as a clamp that limits the input voltage by shunting current away from the input terminal. The clamp circuit operates as a standby protection circuit that may be part of shunt regulator and/or a crowbar system in a shunt regulator. The clamp circuit prevents an "in-rush" of current from creating a dangerous condition in a charging device (i.e., battery operated) when the power source is initially engaged. The clamp circuit is deactivated when the detected power supply voltage is above a battery voltage of the device.