The HC40102 and HC40103 are 8-stage preset-

table synchronous down counters. Carry Out/Zero

Detect (CO/ZD) is output at the ”L” level for the

period of 1 bit when the readout becomes ”0”. The

HC40102 adopts binary coded decimal notation,

making setting up to 99 counts possible. While the

HC40103 adopts 8-bit binary counter and can set up

to 255 counts.

COUNT OPERATION

At the ”H” level of control input of CLEAR, SPE and

APE, the counter carriers out down count operation

one by one at the rise of pulse given to CLOCK input.

Count operation can be inhibited by setting Carry

Input/Clock Enable CI/CE to the ”H” level.

CO/ZD is output at the ”L” level when the readout

becomes ”0” but is not output even if the readout

becomes ”0” when CI/CE is at the ”H” level, thus

maintaining the ”H” level.

Synchronous cascade operation can be carried out

by using CI/CE input and CO/ZD output.

The contents of count jump to maximum count (99

for the HC40102 and 225 for the HC40103) if clock

is given when the readout is ”0”. Therefore, oper-

ation of 100-frequency division and that of 256-fre-

quency division are carried out for the HC40102 and

HC40103, respectively, when clock input alone is

given without various kinds of preset operation.

PRESET OPERATION AND RESET OPERATION

When Clear (CLEAR) input is set to the ”L” level, the

readout is set to the maximum count independetly

of other inputs. When Asynchronous Preset Enable

(APE) input is set to the ”L” level, readouts given on

J0 to J7 can be preset asynchronously to counter in-

dependently of inputs other than CLEAR input.

When Synchronous Preset Enable (SPE) is set to

the ”L” level, the readouts given on J0 to J7 can be

preset to counter synchronously with the rise of

clock.

As to these operation modes, refer to the truth table.

FUNCTIONAL DESCRIPTION

Input

Output

CLEAR APE S P E J

T E CLO CK

LX

X

X

X

X

L

HL

X

L

X

X

L

HL

X

H

X

X

H

HH

L

L

X

_

v

HH

L

H

X

_

v

HH

L

X

X

_

w



_

__

HH

H

X

L

_

v

HH

H

X

H

X

__

M54/M74HC40102/40103

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