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Non-saturating Driver Circuit Disclosure Number: IPCOM000098398D
Original Publication Date: 1960-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 33K

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Wohlfort, WR: AUTHOR [+1]


The circuit provides drive power pulses with fast rise and fall times.

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Non-saturating Driver Circuit

The circuit provides drive power pulses with fast rise and fall times.

With the input to T1 at its more positive or off condition, T2 is slightly conducting and T3 and T4 are shut off. The Zener diode is maintained in its reverse conducting condition through the diode D1, the inductor, and R1. A negative voltage shift at the input turns transistor T1 on, raising its collector voltage to drive T2 into heavy conduction. T2 in turn provides drive current to T4, turning the latter on. As the collector of T4 falls negatively, a point is reached at which diode D2 becomes forwardly biased. This point is determined by the Zener voltage drop, the base emitter drops of T2 and T4, and the drop across the base resistor of T4, and is adjusted so that the conduction point occurs just prior to saturation of T4.

When the input to T1 rises again, T2 is turned off and T3 is turned on. The now conducting transistor T3 rapidly draws base current from T4 to turn the latter off. Since T4 is maintained out of saturation in its on condition, no carrier storage delays are encountered and the turnoff time is extremely short.

In the off condition of the circuit, i.e., when the input is at its positive level, the feedback network including the diode D2 is nonconductive so that power dissipation is at a minimum.


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