Electronic digital logic circuitry – Interface – Logic level shifting
Patent
1997-03-20
1999-03-16
Tokar, Michael
Electronic digital logic circuitry
Interface
Logic level shifting
326 34, 326 83, 326 50, H03K 190948
Patent
active
058835288
ABSTRACT:
An input circuit to a semiconductor device may selectively accept different voltage logic levels (e.g., TTL or CMOS) as selected by a preset selection signal. The selection signal activates an N-type or P-type transistor in the input circuit which alters the threshold switching voltage of the input circuit logic. By altering the input threshold voltage, both TTL and CMOS input signals may be correctly triggered. An additional circuitry may be provided to allow a low voltage circuit (e.g., 3.3 Volts) to be tolerant of higher voltage inputs (e.g., 5 Volts). An isolation transistor isolates the input of the circuit from the high voltage signal, while a pulldown transistor pulls a high logic, high voltage signal down to supply voltage level.
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patent: 5469082 (1995-11-01), Bullinger et al.
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patent: 5521531 (1996-05-01), Okuzumi
patent: 5528172 (1996-06-01), Sundstrom
patent: 5589783 (1996-12-01), McClure
Ahmed Junaid Ahmed
Kashmiri Abdul Qayyum
Kim Han My
Bell Robert P.
Cirrus Logic Inc.
Duong Qui Van
Shaw Steven A.
Tokar Michael
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