SN54ABT162823A, SN74ABT162823A

18BIT BUSINTERFACE FLIPFLOPS

WITH 3STATE OUTPUTS

SCBS666B − JULY 1996 − REVISED JUNE 2004

2

POST OFFICE BOX 655303

description/ordering information (continued)

A buffered output-enable (OE) input places the nine outputs in either a normal logic state (high or low level) or

a high-impedance state. In the high-impedance state, the outputs neither load nor drive the bus lines

significantly. The high-impedance state and increased drive provide the capability to drive bus lines without

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.

The outputs, which are designed to source or sink up to 12 mA, include equivalent 25-

Ω series resistors to

reduce overshoot and undershoot.

disables the outputs, preventing damaging current backflow through the devices when they are powered down.

The power-up 3-state circuitry places the outputs in the high-impedance state during power up and power down,

which prevents driver conflict.

resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

FUNCTION TABLE

(each 9-bit flip-flop)

INPUTS

OUTPUT

OE

CLR

CLKEN

CLK

D

OUTPUT

Q

L

L

X

X

X

L

L

HL

↑

HH

L

HL

↑

LL

L

HL

L

X

Q0

L

HH

X

X

Q0

H

X

X

X

X

Z