Product details

Number of channels 4 Technology family LS Supply voltage (min) (V) 4.5 Supply voltage (max) (V) 5.5 Input type Bipolar Output type 3-State Clock frequency (max) (MHz) 35 IOL (max) (mA) 24 IOH (max) (mA) -2.6 Supply current (max) (µA) 24000 Features High speed (tpd 10-50ns) Operating temperature range (°C) -55 to 125 Rating Military
Number of channels 4 Technology family LS Supply voltage (min) (V) 4.5 Supply voltage (max) (V) 5.5 Input type Bipolar Output type 3-State Clock frequency (max) (MHz) 35 IOL (max) (mA) 24 IOH (max) (mA) -2.6 Supply current (max) (µA) 24000 Features High speed (tpd 10-50ns) Operating temperature range (°C) -55 to 125 Rating Military
CDIP (J) 16 135.3552 mm² 19.56 x 6.92 CFP (W) 16 69.319 mm² 10.3 x 6.73 LCCC (FK) 20 79.0321 mm² 8.89 x 8.89
  • 3-State Outputs Interface Directly With System Bus
  • Gated Output-Control LInes for Enabling or Disabling the Outputs
  • Fully Independent Clock Virtually Eliminates Restrictions for Operating in One of Two Modes:
    • Parallel Load
    • Do Nothing (Hold)
  • For Application as Bus Buffer Registers
  • Package Options Include Plastic Small-Outline (D) Packages, Ceramic Flat (W) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (N) and Ceramic (J) DIPs
  • 3-State Outputs Interface Directly With System Bus
  • Gated Output-Control LInes for Enabling or Disabling the Outputs
  • Fully Independent Clock Virtually Eliminates Restrictions for Operating in One of Two Modes:
    • Parallel Load
    • Do Nothing (Hold)
  • For Application as Bus Buffer Registers
  • Package Options Include Plastic Small-Outline (D) Packages, Ceramic Flat (W) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (N) and Ceramic (J) DIPs

The '173 and 'LS173A 4-bit registers include D-type flip-flops featuring totem-pole 3-state outputs capable of driving highly capacitive
or relatively low-impedance loads. The high-impedance third state and increased high-logic-level drive provide these flip-flops with the capability of being connected directly to and driving the bus lines in a bus-organized system without need for interface or pull-up components. Up to 128 of the SN74173 or SN74LS173A outputs can be connected to a common bus and still drive two Series 54/74 or 54LS/74LS TTL normalized loads, respectively. Similarly, up to 49 of the SN54173 or SN54LS173A outputs can be connected to a common bus and drive one additional Series 54/74 or 54LS/74LS TTL normalized load, respectively. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output control circuitry is designed so that the average output disable times are shorter than the average output enable times.

Gated enable inputs are provided on these devices for controlling the entry of data into the flip-flops. When both data-enable (G\1, G\2) inputs are low, data at the D inputs are loaded into their respective flip-flops on the next positive transition of the buffered clock input. Gate output-control (M, N) inputs also are provided. When both are low, the normal logic states (high or low levels) of the four outputs are available for driving the loads or bus lines. The outputs are disabled independently from the level of the clock by a high logic level at either output-control input. The outputs then present a high impedance and neither load nor drive the bus line. Detailed operation is given in the function table.

The SN54173 and SN54LS173A are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74173 and SN74LS173A are characterized for operation from 0°C to 70°C.

The '173 and 'LS173A 4-bit registers include D-type flip-flops featuring totem-pole 3-state outputs capable of driving highly capacitive
or relatively low-impedance loads. The high-impedance third state and increased high-logic-level drive provide these flip-flops with the capability of being connected directly to and driving the bus lines in a bus-organized system without need for interface or pull-up components. Up to 128 of the SN74173 or SN74LS173A outputs can be connected to a common bus and still drive two Series 54/74 or 54LS/74LS TTL normalized loads, respectively. Similarly, up to 49 of the SN54173 or SN54LS173A outputs can be connected to a common bus and drive one additional Series 54/74 or 54LS/74LS TTL normalized load, respectively. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output control circuitry is designed so that the average output disable times are shorter than the average output enable times.

Gated enable inputs are provided on these devices for controlling the entry of data into the flip-flops. When both data-enable (G\1, G\2) inputs are low, data at the D inputs are loaded into their respective flip-flops on the next positive transition of the buffered clock input. Gate output-control (M, N) inputs also are provided. When both are low, the normal logic states (high or low levels) of the four outputs are available for driving the loads or bus lines. The outputs are disabled independently from the level of the clock by a high logic level at either output-control input. The outputs then present a high impedance and neither load nor drive the bus line. Detailed operation is given in the function table.

The SN54173 and SN54LS173A are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74173 and SN74LS173A are characterized for operation from 0°C to 70°C.

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Technical documentation

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Type Title Date
* Data sheet 4-Bit D-Type Registers With 3-State Outputs datasheet (Rev. A) 01 Jun 1999
Application note Power-Up Behavior of Clocked Devices (Rev. B) PDF | HTML 15 Dec 2022
Selection guide Logic Guide (Rev. AB) 12 Jun 2017
Application note Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) 02 Dec 2015
User guide LOGIC Pocket Data Book (Rev. B) 16 Jan 2007
Application note Semiconductor Packing Material Electrostatic Discharge (ESD) Protection 08 Jul 2004
Application note TI IBIS File Creation, Validation, and Distribution Processes 29 Aug 2002
Application note Designing With Logic (Rev. C) 01 Jun 1997
Application note Designing with the SN54/74LS123 (Rev. A) 01 Mar 1997
Application note Input and Output Characteristics of Digital Integrated Circuits 01 Oct 1996
Application note Live Insertion 01 Oct 1996

Design & development

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Package Pins CAD symbols, footprints & 3D models
CDIP (J) 16 Ultra Librarian
CFP (W) 16 Ultra Librarian
LCCC (FK) 20 Ultra Librarian

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