Switch mode power supply with standby mode operation

A switch mode power supply, comprising:

• a source of an AC, mains supply voltage;
• a load circuit;
• a regulating power stage coupled to said source and responsive to a pulse-width modulated, switching signal for generating an output supply voltage, during both power-on and standby operations and for regulating in a feedback manner said output supply voltage developed in said load circuit during said power-on operation;
• a source of a first on/off control signal that is coupled to said load circuit for significantly reducing an output supply current of said power supply in said load circuit when said on/off control signal is indicative of said standby operation;
• means coupled to said load circuit for generating a feedback signal that is indicative of a magnitude of at least one of said output supply voltage and said output supply current;
• a modulator responsive to said feedback signal for generating said switching signal, during both said power-on and standby operations, that is modulated in accordance with said feedback signal such that, in said standby operation, an interval between transition edges of said switching signal is substantially different than in said power-on operation;
• and
• a detector responsive to said switching signal for generating a second on/off control signal in accordance with said interval between the transition edges of said switching signal.