TECHNICAL DATA
IN74HC166
8-Bit Serial or Parallel-Input/
Serial-Output Shift Register
High-Performance Silicon-Gate CMOS
The IN74HC166 is identical in pinout to the LS/ALS166. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL outputs.
This device is a parallel-in or serial-in, serial-out shift register with
gated clock inputs and an overriding clear input. The shift/load input
establishes the parallel-in or serial-in mode. When high, this input
enables the serial data input and couples the eight flip-flops for serial
shifting with each clock pulse. Synchronous loading occurs on the next
clock pulse when this is low and the parallel data inputs are enabled.
Serial data flow is inhibited during parallel loading. Clocking is done
on the low-to-high level edge of the clock pulse via a two input
positive NOR gate, which permits one input to be used as a clock
enable or clock inhibit function. Clocking is inhibited when either of
the clock inputs are held high, holding either input low enables the
other clock input. This will allow the system clock to be free running
and the register stopped on command with the other clock input. A
change from low-to-high on the clock inhibit input should only be
done when the clock input is high. A buffered direct clear input
overrides all other inputs, including the clock, andsets all flip-flop to
zero.
ORDERING INFORMATION
IN74HC166N Plastic
IN74HC166D SOIC
TA = -55° to 125° C for all packages
PIN ASSIGNMENT
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Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 2.0 to 6.0 V
Low Input Current: 1.0 µA
High Noise Immunity Characteristic of CMOS Devices
LOGIC DIAGRAM
PIN 16 =VCC
PIN 8 = GND
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