Product details

Technology Family HCT Number of channels (#) 1 Operating temperature range (C) -40 to 85 Rating Catalog ICC (Max) (uA) 80
Technology Family HCT Number of channels (#) 1 Operating temperature range (C) -40 to 85 Rating Catalog ICC (Max) (uA) 80
PDIP (N) 16 181 mm² 19.3 x 9.4 SOIC (D) 16 59 mm² 9.9 x 6 SOP (NS) 16 80 mm² 10.2 x 7.8 TSSOP (PW) 16 22 mm² 4.4 x 5 TSSOP (PW) 16 22 mm² 5 x 4.4
  • Operating Voltage Range of 4.5 V to 5.5 V
  • Outputs Can Drive Up To 10 LSTTL Loads
  • Low Power Consumption, 80-µA Max ICC
  • Typical tpd = 17 ns
  • ±4-mA Output Drive at 5 V
  • Low Input Current of 1 µA Max
  • Inputs Are TTL-Voltage Compatible
  • Designed Specifically for High-Speed Memory Decoders and Data Transmission Systems
  • Incorporate Three Enable Inputs to Simplify Cascading and/or Data Reception

  • Operating Voltage Range of 4.5 V to 5.5 V
  • Outputs Can Drive Up To 10 LSTTL Loads
  • Low Power Consumption, 80-µA Max ICC
  • Typical tpd = 17 ns
  • ±4-mA Output Drive at 5 V
  • Low Input Current of 1 µA Max
  • Inputs Are TTL-Voltage Compatible
  • Designed Specifically for High-Speed Memory Decoders and Data Transmission Systems
  • Incorporate Three Enable Inputs to Simplify Cascading and/or Data Reception

The ’HCT138 devices are designed for high-performance memory-decoding or data-routing applications requiring very short propagation delay times. In high-performance memory systems, these decoders can minimize the effects of system decoding. When employed with high-speed memories utilizing a fast enable circuit, the delay times of these decoders and the enable time of the memory usually are less than the typical access time of the memory. This means that the effective system delay introduced by the decoders is negligible.

The conditions at the binary-select inputs and the three enable inputs select one of eight output lines. Two active-low (G)\ and one active-high (G) enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented without external inverters, and a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications.

The ’HCT138 devices are designed for high-performance memory-decoding or data-routing applications requiring very short propagation delay times. In high-performance memory systems, these decoders can minimize the effects of system decoding. When employed with high-speed memories utilizing a fast enable circuit, the delay times of these decoders and the enable time of the memory usually are less than the typical access time of the memory. This means that the effective system delay introduced by the decoders is negligible.

The conditions at the binary-select inputs and the three enable inputs select one of eight output lines. Two active-low (G)\ and one active-high (G) enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented without external inverters, and a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications.

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Technical documentation

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Type Title Date
* Data sheet SN54HCT138, SN74HCT138 datasheet (Rev. E) 15 Sep 2003
Application note Implications of Slow or Floating CMOS Inputs (Rev. E) 26 Jul 2021
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
User guide Signal Switch Data Book (Rev. A) 14 Nov 2003
More literature Logic Cross-Reference (Rev. A) 07 Oct 2003
Application note TI IBIS File Creation, Validation, and Distribution Processes 29 Aug 2002
Application note CMOS Power Consumption and CPD Calculation (Rev. B) 01 Jun 1997
Application note Designing With Logic (Rev. C) 01 Jun 1997
Application note SN54/74HCT CMOS Logic Family Applications and Restrictions 01 May 1996
Application note Using High Speed CMOS and Advanced CMOS in Systems With Multiple Vcc 01 Apr 1996

Design & development

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Evaluation board

14-24-LOGIC-EVM — Generic Logic EVM Supporting 14 through 24 Pin PW, DB, D, DW, NS, P, N, and DGV Packages

This EVM is designed to support any logic device that has a D, DW, DB, NS, PW, P, N, or DGV package in a 14 to 24 pin count.
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Package Pins Download
PDIP (N) 16 View options
SO (NS) 16 View options
SOIC (D) 16 View options
TSSOP (PW) 16 View options

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