Soft-start switch with voltage regulation and current limiting
US6034516A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 11, 1997 |
| Grant date | Mar 7, 2000 |
| Priority date | — |
| Expiry date | Jul 11, 2017 |
Classification
- Technology area (CPC —)General
Abstract
A MOSFET, an op-amp, a comparator circuit, and voltage dividers with capacitors are employed in combination to effectuate a soft-start switch with current limiting. The transconductance of the MOSFET is employed so that no sense resistor is required. The MOSFET and op-amp are configured as a closed-loop feedback circuit in which the output of the op-amp is coupled to the gate of the MOSFET and the inverting input of the op-amp is coupled to the output of the soft-start switch via a voltage divider. A first RC circuit provides a voltage to the non-inverting input of the op-amp which can be triggered to gradually rise from a value close to zero to some reference voltage so as to soft-start a load. Current limiting means are effectuated by a comparator circuit and voltage dividers with capacitors. The current limiting means brings the MOSFET to an OFF state and the non-inverting input of the op-amp close to zero volts if the op-amp charges a second RC circuit so that the voltage drop across its capacitor exceeds a pre-determined limit-reference, and also, once the current limiting means brings the MOSFET to the OFF state, the current limiting means allows the soft-start switch to begi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.