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Driver Circuit

IP.com Disclosure Number: IPCOM000041532D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Culican, EF: AUTHOR [+4]

Abstract

Disclosed is an inverting driver circuit which supplies a given level output and utilizes 5.0- and 1.7-volt power supplies. A clamping mechanism is provided at the output to prevent beta degradation of some emitter input receivers. This circuit also includes a tri-state input which creates a high impedance state at the output when desired. The clamp is designed to hold the base of the Darlington transistor (NodeA-) at about 4.4 volts; the output would therefore have a maximum of 2.9 volts (N N 2 VBE's down). The clamp mechanism uses the 1.7- volt supply and a resistor divider to turn on the clamping transistor T2 when Node A reaches 4.4 volts. The Schottky barrier diode SBD1 is included in the clamping circuit to prevent reliability problems in a portion of the operating region.

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Driver Circuit

Disclosed is an inverting driver circuit which supplies a given level output and utilizes 5.0- and 1.7-volt power supplies. A clamping mechanism is provided at the output to prevent beta degradation of some emitter input receivers. This circuit also includes a tri-state input which creates a high impedance state at the output when desired. The clamp is designed to hold the base of the Darlington transistor (NodeA-) at about 4.4 volts; the output would therefore have a maximum of 2.9 volts (N N 2 VBE's down). The clamp mechanism uses the 1.7- volt supply and a resistor divider to turn on the clamping transistor T2 when Node A reaches 4.4 volts. The Schottky barrier diode SBD1 is included in the clamping circuit to prevent reliability problems in a portion of the operating region. The tri- state control operates by turning transistor T1 on and off. If the tri-state input (TSI) is low, Node B is high and T1 is on. This forces Nodes A and C low, which shuts off transistors T5 and T6. The diode 4 is used to prevent beta degradation of T5 during Tri-state operation. When the tri-state input is high, T1 is off and has no effect on the driver circuit.

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