74LS91 8-Bit Shift Storage Register IC

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74LS91 is a monolithic serial-in, serial-out, 8-bit shift registers utilizing transistor-transistor logic (TTL) circuits, and is composed of eight R-S master-slave flip-flops, input gating, and a clock driver. 74LS91 is a part of the 74XXYY IC series. Single-rail data and input control are gated through inputs A and B and an internal inverter to form the complementary inputs to the first bit of the shift register. The IC 74LS91 is smaller in size and it has a much faster speed which makes it reliable in every kind of device.

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What is a Shift Register?

Shift registers are digital memory circuitry found in devices such as calculators, computers, and data processing systems. With the shift register, data or bits are entered into the system in a serial or parallel manner. data entry is done from one direction, and as more data is added, shift positions until they get to the output end. The two ends are referred to as the left and right end. Movement of data can be from left to right, from right to left, or in both directions to make a bidirectional register.

74LS91 Key Features & Specifications

Technology Family: LS
VCC (Min): 4.75V
VCC (Max): 5.25
Bits (#): 8
Operating Voltage (Nom): 5V
Frequency at normal voltage (Max): 18MHz
Propagation delay (Max): 40ns
IOL (Max): 16mA
IOH (Max):-400uA
Rating: Catalog
Available in 14-pin PDIP, GDIP, PDSO packages

74LS91 Pinout

Pin Name	Pin No.	Description
NC	1	Not used
NC	2	Not used
NC	3	Not used
NC	4	Not used
Vcc	5	Chip Supply Voltage
NC	6	Not used
NC	7	Not used
NC	8	Not used
CLK	9	Clock Input Pin
GND	10	Ground Pin
B	11	Input Pin B
A	12	Input Pin A
QH	13	Shift Register Active high Output pin
QH’	14	Shift Register Active low Output pin