SN74LS674 Serial-out shift registers |

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Serial-out shift registers

Serial-out shift registers - SN74LS674


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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Part number Order 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) IOL (Max) (mA) IOH (Max) (mA) 3-state output Rating Operating temperature range (C)
SN74LS674 Order now LS     4.75     5.25     5     35     40     40     24     -2.6     No     Catalog     0 to 70    
SN54LS674 Samples not available LS     4.75     5.25     5     35     40     40     24     -2.6     No     Military     -55 to 125