Single-Rail Outputs on ‘LS399
Selects One of Two 4-Bit Data Sources and
Stores Data Synchronously with System
Clock
Applications:
Dual Source for Operands and Constants
in Arithmetic Processor; Can Release
Processor Register Files for Acquiring
New Data
Implement Separate Registers Capable of
Parallel Exchange of Contents Yet Retain
External Load Capability
Universal Type Register for Implementing
Various Shift Patterns: Even Has
Compound Left-Right Capabilities

description
This monolithic quadruple two-input multiplexer with
storage provides essentially the equivalent functional
capabilities of two separate MSI functions
(SNB4LS157/SN74LS157 and SN54LS175/
SN74LS175) in a single 16-pin package.
When the word-select input is low, word 1 (A1, B1,
C1, D1) is applied to the flip-flops. A high input to
word select will cause the selection of word 2 (A2,
B2, C2, D2). The selected word is clocked to the
output terminals on the positive-going edge of the
clock pulse.
Typical power dissipation is 37 milliwatts. The
SN54LS399 is characterized for operation over the full
military range of —55°C to 125°C. The SN74LS399
is characterized for operation from 0°C to 70°C.