Philips Semiconductors

Product specification

74F779

8-bit bidirectional binary counter (3-State)

1989 Sep 20

3

LOGIC SYMBOL

I/O0 I/O1 I/O2 I/O3 I/O4 I/O5 I/O6 I/O7

15

16

123567

8

12

TC

9

14

OE

CET

CP

GND=Pin 4

SF01260

S0

S1

11

10

LOGIC SYMBOL (IEEE/IEC)

SF01261

EN4

11

15

14

9

[1]

[2]

[4]

[8]

[16]

[32]

[64]

[128]

4, 5, 8 CT=256

4, 5, 8 CT=0

12

16

1

2

3

5

6

7

8

CTR DIV 256

10

0

1

M

0

3

—

EN6

1–

2 +/C5

LOAD

DOWN

UP

HOLD

6

FUNCTION TABLE

INPUTS

OPERATING MODE

S1

S0

CET

OE

CP

X

X

X

H

X

I/O0 to I/O7 in High impedance

X

X

X

L

X

Flip-flop outputs appear on I/O lines

L

L

X

H

↑

Parallel load all flip-flops

(not LL)

H

X

↑

Hold (TC held High)

H

L

L

X

↑

Count up

L

H

L

X

↑

Count down

H = High voltage level

L = Low voltage level

X = Don’t care

↑ = Low-to-High clock transition

(not LL) = S0 and S1 should never be Low voltage level at the

same time in the hold mode only.