Current limiting using capacitor charge measurement
US6400544B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 23, 1999 |
| Grant date | Jun 4, 2002 |
| Priority date | — |
| Expiry date | Jul 23, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M3/073
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Current limiting using capacitor charge measurement to limit the supply current or load current of a circuit, or the current flowing through a device or switch, to prevent the time average current in the switch from exceeding a certain safe level. A replica circuit is used to provide a scaled version of the current in the main switch. The current output of the replica circuit is used to charge a capacitor during the first period of the clock signal so that the capacitor voltage, at any time during the on time, is proportional to the time integral of the current output of the replica circuit, and thus, the time integral of the current in the main circuit. The capacitor voltage, in turn, is compared with a known voltage to determine whether the charge that has flowed through the main switch has exceeded a predetermined maximum. The output of the comparator may be used in various ways, including as a control of the clock duty cycle to limit the on time of the main switch. Various embodiments are disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.