Electronic digital logic circuitry – Interface – Supply voltage level shifting
Patent
1998-05-11
2000-02-29
Tokar, Michael
Electronic digital logic circuitry
Interface
Supply voltage level shifting
326 84, 326 89, 326109, G03B 124
Patent
active
060313927
ABSTRACT:
A TTL input stage for negative supply voltage systems is described herein which obviates the need for a positive supply and a level shifter. In one embodiment, a first JFET current source, the emitter/collector of a PNP bipolar transistor, and a second JFET current source are connected in series between a control input and a negative supply voltage. The base of the bipolar transistor is connected to ground. At a control input of 2V.sub.be above ground, the PNP transistor has a V.sub.be drop across its emitter/base junction, and each of the identical JFETs has a V.sub.be drop across it. An NPN bipolar transistor, having its base connected to the source of the second JFET and its emitter connected to the negative voltage, is turned on by the V.sub.be drop across the second JFET to provide the output of the TTL input stage. In one embodiment, the TTL input stage is a control circuit for turning an output MOSFET on and off. A circuit providing hysteresis of the threshold for switching between logic levels may be included as part of the TTL input stage.
REFERENCES:
patent: 4945265 (1990-07-01), Estrada
patent: 5013938 (1991-05-01), Estrada
patent: 5561382 (1996-10-01), Ueda et al.
Micrel Incorporated
Ogonowsky Brian D.
Tokar Michael
Tran Anh
LandOfFree
TTL input stage for negative supply systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with TTL input stage for negative supply systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and TTL input stage for negative supply systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-686407