Delay circuit and method for use in reducing relay switching

A delay circuit, being applied in a power conversion device containing a relay unit, and comprising:

• a first terminal, being coupled to a first coil terminal of a relay coil of the relay unit;
• a second terminal, being coupled to a second coil terminal of the relay coil of the relay unit;
• a third terminal, being coupled to a reference ground;
• a first diode, being coupled to the second terminal by a cathode end thereof, and being coupled to a power signal by an anode end thereof;
• a second diode, being coupled to the first terminal by an anode end thereof, and being coupled to a first common connection node of the second terminal and the cathode end of the first diode by a cathode end thereof;
• a BJT element, having an emitter terminal, a collector terminal and a base terminal, wherein the emitter terminal is coupled to the reference ground, and the collector terminal being coupled to a second common connection node of the first terminal and the anode end of the second diode;
• and
• a delay unit, being coupled between the base terminal of the BJT element, the reference ground and the first common connection node;
• wherein in case an electronic device having the power conversion device being operated in a sleep mode, the delay unit applies a time delaying process to the power signal) that is transmitted to the second coil terminal of the relay coil, such that a rising time of each of switch-on pulses contained by the power signal is delayed for a specific time;
• wherein the specific time is equal to or longer than a pulse width of each of power-on pulses contained by a power switching signal of the power conversion device.