Browse Prior Art Database

Short Circuit Protect Latch

IP.com Disclosure Number: IPCOM000093048D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Liu, C: AUTHOR [+2]

Abstract

Clamping a unity gain device 10, such as a series regulator transistor, to a low current flow condition upon shorting of its load 12 prevents overheating.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 97% of the total text.

Page 1 of 2

Short Circuit Protect Latch

Clamping a unity gain device 10, such as a series regulator transistor, to a low current flow condition upon shorting of its load 12 prevents overheating.

Power Ep is applied at terminal 14, through resistor 16 to device 10. Capacitor 20 filters out spikes. A bridge network comprising resistors 16, 22, 24, 26, and 28 is connected to comparator circuit 30. The output 32 of comparator 30 is either up or at ground level. Output voltage from device 10 is fed back along line 34 to amplifier 36. Similarly, a reference voltage Vr is applied to amplifier 36. Output 32 from comparator 30 and output 37 from amplifier 36 joins at summing junction 38 and a biasing or control voltage is supplied to device 10 along line 40.

In normal operation, output 32 of comparator 30 is at up level and diode 42 is nonconducting. Should, however, load 12 be short-circuited, voltage Vo drops suddenly through a wide range.

Current flow through device 10 increases in just as rapid and widely swinging manner, thus heating device 10. Should there be insufficient space to provide a heat sink for device 10, damage may be done to either that device or the surrounding components.

However, diode 42 conducts when Vo drops below a predetermined level. Resistor 44 is a current limiting resistor. Output 32 of comparator 30 is at ground level. Device 10 is thus completely taken out of circuit until such time as the short circuit across load 12 is repaired.

1

Page 2 of 2

2

[This...