Browse Prior Art Database

Self Latching Driver for Gas Panel

IP.com Disclosure Number: IPCOM000086079D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Davis, GT: AUTHOR

Abstract

A drive system which uses the internal device capacitance of a complementary pair of transistors, to furnish current which eliminates the requirement of a DC base drive to a latch circuit operates as follows. Referring to the drawing, the high-voltage bus connected to terminal 3 is turned on across the collector, base and substrate capacitors of transistors Q1 and Q2 to pull node 3 up to set the latch consisting of the NPN-PNP pair of transistors Q1 and Q2, or alternatively a four layer silicon controlled switch device could be employed. Once triggered, this latch will remain set for as long as current flows from the collector of Q1, thus guaranteeing adequate base drive to output transistor Q2.

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Self Latching Driver for Gas Panel

A drive system which uses the internal device capacitance of a complementary pair of transistors, to furnish current which eliminates the requirement of a DC base drive to a latch circuit operates as follows. Referring to the drawing, the high-voltage bus connected to terminal 3 is turned on across the collector, base and substrate capacitors of transistors Q1 and Q2 to pull node 3 up to set the latch consisting of the NPN-PNP pair of transistors Q1 and Q2, or alternatively a four layer silicon controlled switch device could be employed. Once triggered, this latch will remain set for as long as current flows from the collector of Q1, thus guaranteeing adequate base drive to output transistor Q2.

Transistor Q3 is used to pull the base drive of transistor Q2 to ground when the driver is to be held off. Resistor 17 must be small enough to hold transistor Q1 off during the positive high-voltage transitions, but large enough to allow transistor Q1 to turn on if the Cdv/dt current is allowed to turn Q2 on.

The current which turns transistor Q2 on is modified by the beta of Q2 to provide current to pull node 9 down and set the latch, while resistor 15 limits the current flowing through the PNP portion of the latch. This circuit configuration provides several advantages in that the circuit is much smaller than circuits providing the same function, and there is no DC power dissipation in the circuit as long as there is a capacitive load....