Power supply circuit and method thereof to detect demagnitization of the power supply
US6469484B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 20, 2001 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Feb 20, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M3/33507
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A regulator circuit (26) operates a switching power supply (10) in discontinuous conduction mode (DCM) by detecting the state of demagnetization of a transformer (16) of the switching power supply. When a primary current (Ip) reaches zero the voltage across a drain and a source of a switching transistor (18) drops off sharply generating a negative spike in voltage at gate voltage VG. The negative spike in voltage indicates the transformer of the switching power supply is demagnetized. The negative spike is detected by a comparator (44). The comparator provides a signal (DEMAG) to a PWM regulator (46) which provides a first control signal (Lc) to a first transistor (40), and a second control signal (Uc) to a second transistor (42). The first and second transistors turn ON and OFF to enable ON the switching transistor only after the transformer (16) is demagnetized to enable the switching power supply to operate in DCM.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.