HD74HC595
8-bit Shift Register/Latch (with 3-state outputs)
Description
This device each contains an 8-bit serial-in, parallel-out shift register that feeds an 8-bit D-type storage
register. The storage register has parallel 3-state outputs. Separate clocks are provided for both the shift
register and the storage register. The shift register has a direct-overriding clear, serial input, and serial
output pins for cascading.
Both the shift register and storage register clocks are positive-edge triggered. If the user wishes to connect
both clocks together, the shift register state will always be one clock pulse ahead of the storage register.
Features
• High Speed Operation: t
pd
(RCK to Q) = 17 ns typ (C
L
= 50 pF)
• High Output Current: Fanout of 15 LSTTL Loads (Q
A
to Q
H
outputs)
• Wide Operating Voltage: V
CC
= 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: I
CC
(static) = 4 µA max (Ta = 25°C)
Function Table
RCK SCK SCLR G Function
XXXHQ
A
to Q
H
high impedance
X X L X Shift register cleared Q
H
’ = L
X H X Shift register clocked Q
n
= Q
n – 1
, Q
A
= SER
X H X Contents of shift register transferred to output latches