Patent ID: 6680837
Filing Date: 2004-01-20
Classification: H02H

Abstract:
A hiccup-mode short circuit protection circuit suitable for use with a linear voltage regulator which employs an N-type field-effect transistor (FET) as a pass transistor, comprising:a drive signal from a linear voltage regulator's error amplifier suitable for driving the gate of a FET pass transistor connected to said drive signal, said pass transistor arranged to conduct an output current which varies with said drive signal to an output terminal, a first switch circuit arranged to substantially eliminate said drive signal to said pass transistor when the voltage at said output terminal is below a first predetermined threshold voltage indicative of a short-circuit condition, a first current source circuit arranged to charge the gate capacitance of said FET pass transistor while said output terminal voltage is below said predetermined threshold voltage, a second current source circuit arranged to, when the voltage on said gate rises above a second predetermined threshold voltage and said output terminal voltage is below said predetermined threshold voltage, further charge said gate capacitance such that said pass transistor is turned on, and a second switch circuit arranged to, when the voltage on said gate rises above a third predetermined threshold voltage greater than said second predetermined threshold voltage and said output terminal voltage is below said predetermined threshold voltage, discharge said gate capacitance such that said pass transistor is turned off.