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Push Pull Driver with Delta I/ Delta t and Delta v/ Delta t Control

IP.com Disclosure Number: IPCOM000049903D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Gaudenzi, GJ: AUTHOR [+3]

Abstract

The disclosed driver circuit is a push-pull split-phase driver type which is designed to control output transitions by resistor design as compared to the conventional feedback capacitor type.

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Push Pull Driver with Delta I/ Delta t and Delta v/ Delta t Control

The disclosed driver circuit is a push-pull split-phase driver type which is designed to control output transitions by resistor design as compared to the conventional feedback capacitor type.

Consider the case when input A is down, transistors T2, T4 and T7 are off, allowing for T5 and T6 to conduct such that A is up. The rising output transition is controlled by R7 and RCC because as R7 is increased, T4 turns off slower, therefore, controlling the transition at the base of T5; hence the output A will follow.

As input A is pulled up, T2 and T4 turn on fast, turning off T5 and T6. Since TFB is operated in the saturation region, TFB and T8 will turn off slowly. The current that flows in resistor R5, as a result of T2 turning on, will therefore be diverted from the base of T7 and flow in the collectors of T8 and TFB (negligible amount in R6). As TFB and T8 turn off slowly, the current into the base of T7 will increase at a rate Delta IB/ Delta t (T7), which is determined by the magnitude of resistor RSFB. As RSFB decreases, the level of saturation of TFB is increased; therefore, T8 turns off slower, causing a lower Delta IB/ Delta t (T7). The ramping of the base current of T7 will control the rate of change of the collector current since Delta IC/ Delta t equals Beta Delta IB/ Delta t. The result of the collector current current of T7 increasing at a controlled rate has the effect of limiting the ra...