Method and apparatus for virtual current sensing in DC-DC switched mode power supplies
US6377032B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 2000 |
| Grant date | Apr 23, 2002 |
| Priority date | — |
| Expiry date | Jul 20, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B70/10
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An apparatus and method for virtual current sensing in a DC-DC switched mode power supply. In a fixed frequency implementation, when a switching phase begins, the phase node goes high when the high-side switching transistor is turned on. At this point, a first programmable current source begins charging a current sensing capacitor and the voltage across the capacitor simulates the rising slope of the voltage across a conventional current sensing resistor. Simultaneously, a ramp capacitor beginning at a reference voltage is charged by a second programmable current source. When the sum of the voltages across the two capacitors exceeds an error voltage, the phase node goes low when the drive signal to the transistor is turned off. At this point, a third programmable current source begins discharging the current sensing capacitor and the voltage across the capacitor simulates the falling slope of the current across the conventional resistor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.