Browse Prior Art Database

High Power Current Sink With Low Power Transistor

IP.com Disclosure Number: IPCOM000096727D
Original Publication Date: 1963-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Fitzgerald, FC: AUTHOR

Abstract

This circuit allows a low power transistor to operate as a high power, high current sink. The current in the sink is defined by the potential across R2. This potential is maintained constant by means of the voltage clamping action of the base-emitter junction of the transistor at node A.

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 100% of the total text.

Page 1 of 2

High Power Current Sink With Low Power Transistor

This circuit allows a low power transistor to operate as a high power, high current sink. The current in the sink is defined by the potential across R2. This potential is maintained constant by means of the voltage clamping action of the base-emitter junction of the transistor at node A.

R1 is chosen such that the current through it equals the sink current, when the maximum voltage level is on the signal line. The base bias of the transistor is chosen such that the transistor is in saturation, when the minimum voltage level is on the signal line.

Thus, the sink current is proportioned between R1 and the transistor at all signal voltage levels. R1 dissipates the greater proportion of the power at high voltage levels. The transistor handles high current after it has gone into saturation (low voltage level). This minimizes the power dissipated in the transistor.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]