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Low Power I/O Channel Driver

IP.com Disclosure Number: IPCOM000049769D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Amante, WJ: AUTHOR [+2]

Abstract

This five-volt channel driver provides non-latching, current sensing, short-circuit protection of its output, with low-power dissipation and a low number of active components.

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Low Power I/O Channel Driver

This five-volt channel driver provides non-latching, current sensing, short- circuit protection of its output, with low-power dissipation and a low number of active components.

When the input and inhibit are low, T2 and T4 will be off. This will cause T5 also to be off. Current will now flow out of the main output device T13 and cause a high logic level at the output. Device T12 will also be outputting current but proportionally less than T13. Device T11 then senses this current and provides additional base drive for T9, T12 and T13 through T10. The more output current needed, the more base drive to T13 will be supplied without causing a larger drop across R5 and therefore an output voltage drop. The extra base drive by T10 allows R5 to have a high value and therefore the driver to have a lower overall power dissipation.

When either the input or inhibit goes to a high state, T2 or T4 will turn on. This will then turn T5 on and saturate it. This will turn T13 off, as it will T9 and T12. With T12 off, T11 will sense no current and then have T10 source no base drive out to T13.

When the output is in s logical high and the output sees a lower than normal output resistance (a short), extra current will be drawn out of T13. Since T9 sees an output current proportional to T13, its collector current increase will cause an increase in the drop across R6. This will turn on T6 and then T7. T7 will then saturate T8 which will then start to turn o...