Patent Number: 6,480,401

Title: Method and apparatus for reducing standby power in power supplies

Abstract: Power consumption of a low-power flyback power converter under standby-load or no-load conditions is reduced by modulating the OFF time of the flyback transformer's main switch as a function of the feedback control current when the load drops below a predetermined level. This modulation overcomes the conventional frequency-increasing modulation of the ON time at low output power levels so as to reduce the switching frequency, and hence the switching losses, to minimal levels as the load is reduced. Excessive frequency reduction can optionally be avoided by a clamping feature that limits the expansion of the OFF time.

Inventors: Tang; Allen (Valiant Park, HK)

Assignee: Astec International Limited

International Classification: H02M 3/335 (20060101); H02M 3/24 (20060101); H02M 003/335 ()

Expiration Date: 11/12/2019