| US 7,551,460 B2 | ||
| Switch mode power supply controllers | ||
| Vinod A. Lalithambika, Cambridge (United Kingdom); Devarahandi Indika Mahaesh de Silva, Cambridge (United Kingdom); Jayaraman Kumar, Cambridge (United Kingdom); and Gehan Amaratunga, Cambridge (United Kingdom) | ||
| Assigned to Cambridge Semiconductor Limited, (United Kingdom) | ||
| Filed on Jun. 01, 2006, as Appl. No. 11/445,476. | ||
| Claims priority of application No. 0610208 (GB), filed on May 23, 2006. | ||
| Prior Publication US 2007/0274112 A1, Nov. 29, 2007 | ||
| Int. Cl. H02M 3/335 (2006.01) | ||
| U.S. Cl. 363—21.16 [363/41; 323/286] | 26 Claims |
| 1. A switch mode power supply (SMPS) controller for regulating the output of a discontinuous conduction mode SMPS in response
to a feedback signal from a winding of a magnetic energy storage device forming part of an output circuit of said SMPS, said
feedback signal having a waveform with a decaying portion representing a decaying voltage in said output circuit of said SMPS
followed by an oscillatory portion when substantially no energy is being transferred to said SMPS output, the SMPS controller
comprising:
a feedback signal input to receive said feedback signal waveform, said feedback signal waveform being responsive to a voltage
on said winding;
a first timing signal generator coupled to said feedback signal input to identify a first reference point in said feedback
signal waveform at a transition between said decaying and oscillatory portions of said waveform and having an output to provide
a first timing signal responsive to said identification;
a second timing signal generator coupled to said feedback signal input to identify a second point located in said oscillatory
portion of said feedback signal waveform and having an output to provide a second timing signal responsive to said identification;
an area correlator coupled to said feedback signal input and to said first and second timing signal generator outputs, said
area correlator being configured to compare an area under said feedback signal waveform between a start point defined by said
first timing signal and an end point defined by said second timing signal with a reference and having an output to provide
an error signal responsive to said comparison; and
a controller output coupled to said area correlator output.
|