Product details

Supply voltage (min) (V) 4.75 Supply voltage (max) (V) 5.25 Number of channels 8 IOL (max) (mA) 24 IOH (max) (mA) -15 Input type TTL Output type 3-State Features High speed (tpd 10-50ns) Technology family LS Rating Catalog Operating temperature range (°C) 0 to 70
Supply voltage (min) (V) 4.75 Supply voltage (max) (V) 5.25 Number of channels 8 IOL (max) (mA) 24 IOH (max) (mA) -15 Input type TTL Output type 3-State Features High speed (tpd 10-50ns) Technology family LS Rating Catalog Operating temperature range (°C) 0 to 70
SOIC (DW) 24 159.65 mm² 15.5 x 10.3
  • Independent Registers for A and B Buses
  • Multiplexed Real-Time and Stored Data
  • Choice of True or Inverting Data Paths
  • Choice of 3-State or Open-Collector Outputs
  • Included Among the Package Options Are Compact 24-pin 300-mil-Wide Plastic and Ceramic DIPs, Ceramic Chip Carriers, and Plastic "Small Outline" Packages
  • Dependable Texas Instruments Quality and Reliability
  • Independent Registers for A and B Buses
  • Multiplexed Real-Time and Stored Data
  • Choice of True or Inverting Data Paths
  • Choice of 3-State or Open-Collector Outputs
  • Included Among the Package Options Are Compact 24-pin 300-mil-Wide Plastic and Ceramic DIPs, Ceramic Chip Carriers, and Plastic "Small Outline" Packages
  • Dependable Texas Instruments Quality and Reliability

These devices consist of bus transceiver circuits with 3-state or open-collector outputs, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal registers. Data on the A or B bus will be clocked into the registers on the low-to-high transition of the appropriate clock pin (CAB or CBA). The following examples demonstrate the four fundamental bus-management functions that can be performed with the octal bus transceivers and registers.

Enable (G\) and direction (DIR) pins are provided to control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either register or in both. The select controls (SAB and SBA) can multiplex stored and real-time (transparent mode) data. The direction control determines which bus will receive data when enable G\ is active (low). In the isolation mode (control G\ high), A data may be stored in one register and/or B data may be stored in the other register.

When an output function is disabled, the input function is still enabled and may be used to store and transmit data. Only one of the two buses, A or B, may be driven at a time.

The SN54' family is characterized for operation over the full military temperature range of –55°C to 125°C. The SN74' family is characterized for operation from 0° to 70°C.

These devices consist of bus transceiver circuits with 3-state or open-collector outputs, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal registers. Data on the A or B bus will be clocked into the registers on the low-to-high transition of the appropriate clock pin (CAB or CBA). The following examples demonstrate the four fundamental bus-management functions that can be performed with the octal bus transceivers and registers.

Enable (G\) and direction (DIR) pins are provided to control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either register or in both. The select controls (SAB and SBA) can multiplex stored and real-time (transparent mode) data. The direction control determines which bus will receive data when enable G\ is active (low). In the isolation mode (control G\ high), A data may be stored in one register and/or B data may be stored in the other register.

When an output function is disabled, the input function is still enabled and may be used to store and transmit data. Only one of the two buses, A or B, may be driven at a time.

The SN54' family is characterized for operation over the full military temperature range of –55°C to 125°C. The SN74' family is characterized for operation from 0° to 70°C.

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Technical documentation

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Type Title Date
* Data sheet SN54LS646 THRU SN54LS649, SN74LS646 THRU SN74LS649 datasheet (Rev. A) 22 Apr 2004
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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Evaluation board

14-24-LOGIC-EVM — Logic product generic evaluation module for 14-pin to 24-pin D, DB, DGV, DW, DYY, NS and PW packages

The 14-24-LOGIC-EVM evaluation module (EVM) is designed to support any logic device that is in a 14-pin to 24-pin D, DW, DB, NS, PW, DYY or DGV package,

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SOIC (DW) 24 View options

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