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Browse Prior Art Database

High Performance Push-Pull Latch Driver

IP.com Disclosure Number: IPCOM000047202D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Chan, YH: AUTHOR [+2]

Abstract

The push-pull latch driver disclosed herein exhibits a wide operating margin with respect to temperature and power supply variations. The driver's pull-down devices are driven directly from the power supply rather than through a resistor/transistor combination to thereby minimize the effect of temperature and power supply variations. Fig. 1 illustrates a push-pull latch driver which has a narrow operating margin with respect to temperature and power supply variations. The narrow operating margin arises from the fact that pull-down transistors T9 and T10 are driven by the R2 - T2 - R4 and R1 - T1 - R3 networks, respectively. Under nominal conditions (i.e., Vcc = 1.4 V; VT = -0.7 V; VBE = 0.8 V) there are 350 MV across R3 or R4 to define a drive current for R5-T10 or R6-T9. However, under extreme conditions (e.g., Vcc=1.

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High Performance Push-Pull Latch Driver

The push-pull latch driver disclosed herein exhibits a wide operating margin with respect to temperature and power supply variations. The driver's pull-down devices are driven directly from the power supply rather than through a resistor/transistor combination to thereby minimize the effect of temperature and power supply variations. Fig. 1 illustrates a push-pull latch driver which has a narrow operating margin with respect to temperature and power supply variations. The narrow operating margin arises from the fact that pull-down transistors T9 and T10 are driven by the R2 - T2 - R4 and R1 - T1 - R3 networks, respectively. Under nominal conditions
(i.e., Vcc = 1.4 V; VT = -0.7 V; VBE = 0.8 V) there are 350 MV across R3 or R4 to define a drive current for R5-T10 or R6-T9. However, under extreme conditions (e.g., Vcc=1.315 V; VT=-0.627 V; VBE=0.88 V) there may not be sufficient voltage across R3 - R5 or R4 - R6 to turn on T9 or T10, so that the circuit will not operate.

Fig. 2 illustrates the high performance push-pull latch driver. Pull-down devices T9-T10 are now driven by R7 and R8 directly from the power supply. Diodes D5 and D6 are current-steering devices for pulling down node 7 or 8 when T9 or T10 is turned off. Since T9 and T10 are not driven by R1-T1 and R2-T2, operating margin with respect to changes in power supply voltage, temperature and device tolerance is greatly improved.

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