Serial-out shift registers - SN74LS674


Serial-out shift registers



SN54LS673, SN74LS673

The 'LS673 is a 16-bit shift register and a 16-bit storage register in a single 24-pin package. A three-state input/output (SER/Q15) port to the shift register allows serial entry and/or reading of data. The storage register is connected in a parallel data loop with the shift register and may be asynchronously cleared by taking the store-clear input low. The storage register may be parallel loaded with shift-register data to provide shift-register status via the parallel outputs. The shift register can be parallel loaded with the storage-register data upon commmand.

A high logic level at the chip-level (CS\) input disables both the shift-register clock and the storage register clock and places SER/Q15 in the high-impedance state. The store-clear function is not disabled by the chip select.

Caution must be exercised to prevent false clocking of either the shift register or the storage register via the chip-select input. The shift clock should be low during the low-to-high transition of chip select and the store clock should be low during the high-to-low transition of chip select.

SN54LS674, SN74LS674

The 'LS674 is a 16-bit parallel-in, serial-out shift register. A three-state input/output (SER/Q15) port provides access for entering a serial data or reading the shift-register word in a recirculating loop.

The device has four basic modes of operation:

  1. Hold (do nothing)
  2. Write (serially via input/output)
  3. Read (serially)
  4. Load (parallel via data inputs)

Low-to-high-level changes at the chip select input should be made only when the clock input is low to prevent false clocking.


  • 'LS673
    • 16-Bit Serial-In, Serial-Out Shift Register with 16-Bit Parallel-Out Storage Register
    • Performs Serial-to-Parallel Conversion
  • 'LS674
    • 16-Bit Parallel-In, Serial-Out Shift Register
    • Performs Parallel-to-Serial Conversion

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Other qualified versions of SN74LS674

Version Part Number Definition
Military SN54LS674 QML certified for Military and Defense Applications

Parametrics Compare all products in Shift Register

Technology Family
VCC (Min) (V)
VCC (Max) (V)
Voltage (Nom) (V)
F @ Nom Voltage (Max) (Mhz)
ICC @ Nom Voltage (Max) (mA)
tpd @ Nom Voltage (Max) (ns)
Output Drive (IOL/IOH) (Max) (mA)
3-State Output
Operating Temperature Range (C)
SN74LS674 SN54LS674
LS    LS   
4.75    4.75   
5.25    5.25   
5    5   
35    35   
40    40   
40    40   
24/-2.6    24/-2.6   
No    No   
Catalog    Military   
0 to 70    -55 to 125   
24SOIC    24CDIP