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PS8090C 02/07/00

Product Description

Pericom Semiconductor’s PI74ALVCH series of logic circuits are

produced in the Company’s advanced 0.5 micron CMOS

technology, achieving industry leading speed.

The PI74ALVCH16721 is a 20-bit flip-flop with 3-state outputs

PI74ALVCH16721 is designed with edge-triggered D-type flip-

flops with qualified clock storage. On the positive transition of

clock (CLK) input, the device provides true data at the Q outputs,

provided that the clock-enable (CLKEN) input is LOW. If CLKEN

is HIGH, no data is stored.

A buffered output-enable (OE) input can be used to place the

20 outputs in either a normal logic state (HIGH or LOW level) or

a high-impedance state. In the high-impedance state, the outputs

neitherloadnordrivethebuslinessignificantly.Thehigh-impedance

state and increased drive provide the capacity to drive bus lines

without the need for interface or pullup components. OE does not

affect the internal operation of the flip-flops. Old data can be

retained or new data can be entered while the outputs are in the

high-impedance state.

To ensure the high-impedance state during power up or power

minimum value of the resistor is determined by the current-sinking

capability of the driver.

The PI74ALVCH16721 data has “Bus Hold” which retains the

data input’s last state whenever the data input goes to high-

impedance preventing “floating” inputs and eliminating the need

for pullup/down resistors.

Product Features

• PI74ALVCH16721 is designed for low voltage operation

• Hysteresis on all inputs

• Bus Hold retains last active bus state during 3-STATE,

eliminating the need for external pullup resistors

• Industrial operation at –40°C to +85°C

• Packages available:

– 56-pin 240 mil wide plastic TSSOP (A)

– 56-pin 300 mil wide plastic SSOP (V)

Logic Block Diagram

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3.3V 20-Bit Flip-Flop

with 3-STATE Outputs

PI74ALVCH16721