DM74LS164N
© 2000 Fairchild Semiconductor Corporation DS006398 www.fairchildsemi.com
August 1986
Revised April 2000
DM74LS164 8-Bit Serial In/Parallel Out Shift Register
DM74LS164
8-Bit Serial In/Parallel Out Shift Register
General Description
These 8-bit shift registe rs feature gated serial inpu ts and
an asynchronous clear. A low logic level at either input
inhibits entry of the new data, and resets the first flip-flop to
the low level at t he next clock pulse , thus providing com -
plete control over incoming data. A high logic level on
either input enables the other input, which will then dete r-
mine the state of the first flip-flo p. Data at the serial inputs
may be changed while th e cloc k is HIG H or LOW, but only
information meeting th e setup and ho ld time require ments
will be entered. Clocking occurs on the LOW-to-HIGH level
transition of the clock input. All inputs are diode-clamped to
minimize transmission-line effects.
Features
■ Gated (enable/disable) serial inputs
■ Fully buffered clock and serial inputs
■ Asynchronous clear
■ Typical clock frequency 36 MHz
■ Typical power dissipation 80 mW
Ordering Code:
Devices also availab le in Tape and Reel. Specify by appending th e s uffix let t er “X” to the ordering code.
Connection Diagram Function Table
H = HIGH Level (steady state)
L = LOW Level (steady state)
X = Don't Care (any input, including transitions)
↑ = Transition from LOW-to-HIGH level
Q
A0
, Q
B0
, Q
H0
= The level of Q
A
, Q
B
, or Q
H
, respectively, before the
indicated steady-s t at e input conditions we re es t ablished.
Q
An
, Q
Gn
= The level of Q
A
or Q
G
before the most recent ↑ transition of the
clock; indicates a one-bit shift.
Order Number Package Number Package Description
DM74LS164M M14A 14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-120, 0.150 Narrow
DM74LS164N N14A 14-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Inputs Outputs
Clear Clock A B
Q
A
Q
B
...
Q
H
LXXXLL...L
HLXXQ
A0
Q
B0
... Q
H0
H ↑ HHHQ
An
... Q
Gn
H ↑ LX L Q
An
... Q
Gn
H ↑ XL L Q
An
... Q
Gn
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DM74LS164
Logic Diagram
Timing Diagram
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