Diodes 74HCT595 User Manual
Page 3
74HCT595
Document number: DS35493 Rev. 3 - 2
3 of 11
July 2013
© Diodes Incorporated
Preliminary
74HCT595
Functional Description and Timing Diagram
Control Input
Output
Function
SHCP STCP OE MR DS Q7S
Qn
X X L
L
L NC
Low-level asserted on MR clears shift register
Storage register is unchanged
X
↑
L L
L
L
Empty shift register transferred to storage register
X X
H
L
L
Z
Shift register remains clear; All Q ouputs in Z state
↑ X
L
H
Q6S NC
HIGH is shifted into first stage of Shift Register Contents of each
register shifted to next register
The content of Q6S has been shifted to Q7S and now appears on
device pin Q7S
X
↑
L H
NC QnS
Contents of shift register copied to storage register
With output now in active state, the storage resister contents
appear on Q outputs
↑
↑ L H
Q6S QnS
Contents of shift register copied to output register then shift register
shifted.
H=HIGH voltage state
L=LOW voltage state
↑=LOW to HIGH transition
X= don’t care – high or low (not floating)
NC= No change
Z= high-impedance state