1

PS2084B

01/13/97

Product Description

Pericom Semiconductor’s PI74FCT series of logic circuits are

produced in the Company’s advanced 0.6 micron CMOS

technology, achieving industry leading speed grades. All

PI74FCT2XXX devices have a built-in 25 ohm series resistor on

all outputs to reduce noise due to reflections, thus eliminating the

need for an external terminating resistor.

The PI74FCT191T is a high speed CMOS 4-bit binary up/down

counter. It has a single clock with clock enable and up/down

control inputs and ripple carry output. The 191 has asynchronous

preload inputs which override the count inputs. All inputs have

clamp diodes for undershoot noise suppression. All outputs have

ground bounce suppression.

Logic Block Diagram

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Product Features

• PI74FCT191/2191T is pin compatible with bipolar FAST™

Series at a higher speed and lower power consumption

•25

Ω series resistor on all outputs (FCT2XXX only)

• TTL input and output levels

• Low ground bounce outputs (25

Ω series only)

• Extremely low static power

• Hysteresis on all inputs

• Industrial operating temperature range: –40°C to +85°C

• Packages available:

– 16-pin 150 mil wide plastic QSOP (Q)

– 16-pin 300 mil wide plastic SOIC (S)

PI74FCT191T

(25

Ω

Ω

Ω

Ω

Ω Series) PI74FCT2191T

High Speed CMOS Presettable Synchronous

4-Bit Binary Counters

CE

PL

CP

U/D

TC

RC

25

Ω

Ω

Ω

Ω

Ω (FCT2XXX ONLY)

25

Ω

Ω

Ω

Ω

Ω (FCT2XXX ONLY)

25

Ω

Ω

Ω

Ω

Ω (FCT2XXX ONLY)

=F

=0

Cup

Q+Cup

- Cdn

Cdn