This monolithic quadruple two-input multiplexer with storage provides essentially the equivalent functional capabilities of two separate MSI functions (SN54LS157/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.

• 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

• Technology Family
• LS
• Function
• Digital Multiplexer
• Configuration
• 2:1
• Number of channels (#)
• 4
• Operating temperature range (C)
• -55 to 125
• Rating
• Military

SN54LS399的完整型号有：8415401EA、SN54LS399J、SNJ54LS399J，以下是这些产品的关键参数及官网采购报价：

8415401EA，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网8415401EA的批量USD价格：13.691（1000+）

SN54LS399J，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SN54LS399J的批量USD价格：10.231（1000+）

SNJ54LS399J，工作温度：-55 to 125，封装：CDIP (J)-16，包装数量MPQ：1个，MSL 等级/回流焊峰值温度：N/A for Pkg Type，引脚镀层/焊球材料：SNPB，TI官网SNJ54LS399J的批量USD价格：13.691（1000+）