Browse Prior Art Database

Semiconductor Switch Drive Circuit

IP.com Disclosure Number: IPCOM000089281D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Ellis, JJ: AUTHOR

Abstract

The circuit of Fig. 1 provides a regulated I(B1) and a negative hold off voltage for the power transistor switch (PTX).

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Semiconductor Switch Drive Circuit

The circuit of Fig. 1 provides a regulated I(B1) and a negative hold off voltage for the power transistor switch (PTX).

Initially, at Power On, the main controls input 10 for the PTX holds PTX off, i.e., the base drive transistor Q(1) for PTX is off. During this time interval the switching regulator comprising S(1), L(1), D(1), D(2), R(1), C(1) establishes a regulated voltage on C(1). The voltage on C(1) is the negative bias for the drive circuit. In this regulator circuit D(1) allows On drive to be switched in and out, D(2) is a free wheeling diode, I(L1) is the regulated source of I(B1), and R(1) is the dominant load on the switching regulator.

When V(C1) reaches the steady-state, PTX can now be switched on and off. To turn the PTX on, I(B2) is turned off and Q(1) is turned on. To turn the PTX off, I(B2) is turned on, and Q(1) is turned off.

When Q(1) is turned on, the current I(L1) is diverted from D(1) to Q(1).

If I(L1) is used as the input to the Switch Reg. Controls, the regulation of I(L1) will be improved at the expense of V(C1). In Fig. 2 this is accomplished by using a signal from R(CS), which is in series with the current through L(1).

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