HIT HD74HC393 Datasheet
HD74HC393
Dual 4-bit Binary Counters
Description
The HD74HC393 contain two 4-bit ripple carry binary counters, which can be cascaded to create a single
divide-by-256 counter.
The HD74HC393 is incremented on the high to low transition (negative edge) of the clock input, and each
has an independent clear input. when clear is set high all four bits of each counter are set to a low level.
This enables count trucation and allows the implementation of divide-by-N counter configurations.
Features
• High Speed Operation: tpd (A to QA) = 16 ns typ (CL = 50 pF)
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: VCC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)
Function Table
Clock Clear Outputs
XH L
H L No change
L L No change
L No change
L Advance to next state
HD74HC393
(
)
Pin Arrangement
1
1A V
1Q
1QB
2
A
3
4
CLR
Q
A
QB
CLR
Q
A
1Clear
A
Outputs
1QC
QC
5
QB
A
1QD
GND
6
QD
7
QC
QD
Top view
14
13
12
11
10
9
8
CC
2A
2Clear
2Q
A
2QB
2QC
2QD
Outputs
2
Block Diagram (1/2)
Clock
HD74HC393
A
C
Q
Q
Clear
D
D
D
D
Q
C
Q
Q
C
Q
Q
C
Q
Q
QB
QC
QD
3
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