Level Converting Driver Circuit With AC Clamps
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
The disclosed driver circuit is designed to receive ground-down off-chip levels at input A and convert them to ground-up off-chip levels at output A . Included are transistors TSI and TS2 with their base resistors RS and RS1 such that the tristate function is performed when input Z is Up. For this condition the collector of T2 is Down N.1 V and its base is also Down N.7 V insuring that T4, T7, and T7A are off. The driver circuit is configured with a TTL-type input formed by D1 and T1. Diode D1 causes the base of T1 to have a reference potential N-.75 V which tracks with the -1.5 V power supply. Diodes D2 and D3 with resistor R1 are included to raise the Down-level voltage at the base of T2 to insure AC performance. When input A is down N-1.9 V, T1, D2, and D3 conduct, causing the voltage at the base of T2 to be N.