Startup circuit for a switched power supply
US4563733A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 6, 1984 |
| Grant date | Jan 7, 1986 |
| Priority date | — |
| Expiry date | Mar 6, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S323/901
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A startup circuit has an undervoltage monitoring unit and a pulse width modulator PBM with at least one soft start input and one enable input. When switching on the power pack, the undervoltage monitoring unit is disabled until the voltage level at the output has reached a rated value. Outputs of two comparators are connected to the enable input of the pulse width modulator over a NAND gate. A capacitor chargeable via a resistor is applied to the first input of the first comparator with a controllable electronic switch connected in parallel to the capacitor. A first reference voltage is applied to the second input of the first comparator and a second reference voltage equal to or lower than the first reference voltage is connected to the first input of the second comparator. The output voltage of the power pack is connected to the second input thereof. The voltage generated at the capacitor is connected to the soft start input of the pulse width modulator over a biased rectifier whose bias voltage is equal to or lower than the first reference voltage. A control circuit comprising an input for switch-on instructions and an input for switch-off instructions is connected at its output…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.