74F269_5

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Product data sheet

Rev. 05 — 25 March 2010

6 of 19

NXP Semiconductors

74F269

8-bit bidirectional binary counter

6.

Functional description

6.1 Function table

[1]

H = HIGH voltage level steady state

h = HIGH voltage level one set-up time prior to the LOW-to-HIGH clock transition

L = LOW voltage level steady state

l = LOW voltage level one set-up time prior to the LOW-to-HIGH clock transition

qn = Lower case letters indicate state of referenced output prior to the LOW-to-HIGH clock transition

X = don’t care

↑ = LOW-to-HIGH clock transition

* = The TC is LOW when CET is LOW and the counter is at terminal count

Terminal count up is with all Qn outputs HIGH and terminal count down is with all Qn outputs LOW.

Table 3.

Function table[1]

Operating modes

Input

Output

CP

U/D

CEP

CET

PE

Dn

Qn

TC

Parallel load (Dn to Qn)

↑

XX

XI

I

L

*

↑

XX

Xl

h

H

*

Count up (increment)

↑

h

I

I

h

X

count up

*

Count down (decrement)

↑

I

I

I

h

X

count down

*

Hold (do nothing)

↑

Xh

I

h

Xqn

*

↑

XX

h

h

Xqn

H