Simple MOSFET gating delay scheme for SMPS start-up in the standby power reduction circuit

This study presents a simple ultra-low standby power control analogue circuit for home appliances using an AC power relay and charge capacitor for the gating delay of metal-oxide-semiconductor field-effect transistor (MOSFET) to control the power relay. In the standby mode, the AC power is fully disconnected by the relay to the home appliance, and connected by the user input action. To make sure there is enough time for the SMPS and the main MCU initialization, a simple charge capacitor and parallel connected sustaining signal are proposed. The capacitor saves the power during the user input action, and discharges to sustain the gating of MOSFET up to the SMPS activation. After start-up the SMPS and main MCU of home appliance, user input can be detected by the main MCU of home appliance, and the main MCU produces the sustain signal to keep the turn-on state. In the turn-off operation, the main MCU cuts off the sustaining signal by detecting of the user input signal. After the user input action to turn-off the power, the main AC power can be disconnected after the discharging of capacitor. The operating modes and power consumptions are analysed in the simulation and experimental results.