Browse Prior Art Database

Overcurrent Undervoltage Latching Control for Switching Regulator

IP.com Disclosure Number: IPCOM000051993D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Sorensen, DF: AUTHOR

Abstract

The pulse-width modulated (PWM) transistor switching regulator (TSR) illustrated includes a protection circuit sensitive to saturation of the control loop of the regulator to shut down the regulator and latch it in off condition.

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Overcurrent Undervoltage Latching Control for Switching Regulator

The pulse-width modulated (PWM) transistor switching regulator (TSR) illustrated includes a protection circuit sensitive to saturation of the control loop of the regulator to shut down the regulator and latch it in off condition.

Switching transistor 10 is turned on and off by pulse-width modulator 12 so as to chop DC input 14 into a string of pulses fed by a line 16 to output rectifier and filter 18 for providing regulated DC to load 20. The regulation is provided via a feedback loop 22 by which a portion of the output voltage is compared in a operational amplifier 24 with a voltage reference 26 to provide an error signal on line 28. The error signal is connected as a control input to pulse-width modulator
12.

The operation of the control loop is such that when the voltage applied to the load 20 is low, pulse-width modulator 12 increases the width of pulses applied to the control of transistor switch 10 to deliver more energy through output rectifier and filter 18. A current limit control 30, sensitive to the current through switch 10, operates as an over-ride control input 32 so that if the current through transistor switch 10 approaches a dangerous level, the width of the pulses emitted by the pulse width modulator 12 is limited or reduced.

Accordingly, the signal and feedback line 22 can be low if there is a short circuit at load 20, or if current limit control 30 operates to deprive the output...