Browse Prior Art Database

Direction Switch for Off-Chip Driver Circuit

IP.com Disclosure Number: IPCOM000041555D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Favata, AF: AUTHOR [+3]

Abstract

The disclosed switch circuit is utilized either to select or disable/ enable driver circuits (not shown). The circuit will pick either the right or left driver (not shown) by the logical operation of output L or R. The control is via the R/L (select) input. The enable/disable control, input I, will affect both L and R. The circuit operation is as follows: When I is down (-) and the R/L input is up (+), T1 must conduct causing L to be down (-). Under this condition all drivers (not shown) connected to the L output will be enabled. With T1 conducting, T3 and TR are off and output R is up (+). All drivers (not shown) connected to output R are disabled. By this technique the left drivers have been selected for operation.

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Direction Switch for Off-Chip Driver Circuit

The disclosed switch circuit is utilized either to select or disable/ enable driver circuits (not shown). The circuit will pick either the right or left driver (not shown) by the logical operation of output L or R. The control is via the R/L (select) input. The enable/disable control, input I, will affect both L and R. The circuit operation is as follows: When I is down (-) and the R/L input is up (+), T1 must conduct causing L to be down (-). Under this condition all drivers (not shown) connected to the L output will be enabled. With T1 conducting, T3 and TR are off and output R is up (+). All drivers (not shown) connected to output R are disabled. By this technique the left drivers have been selected for operation. If the R/L input is brought down (-), T1 will turn off, causing the output L to go up (+) and T3 and TR will turn on. Output R will be down (-), and the right drivers (not shown) are selected for operation. The enable/disable function is controlled by input I. When input I is up (+), the chip is disabled since T2 is on and T3 cannot conduct. Therefore, output R is up (+). Transistors TI and TII are on, and transistor TL cannot conduct. Therefore, output L is also up (+). With outputs L and R each up (+), neither the right nor left drivers (not shown) can be active. When input I is down (-), T2 and TI are each off and the state of outputs L and R is now dependent on input R/L.

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