The ´ALS138A and ´AS138 are 3-line to 8-line decoders/demultiplexers designed for high-performance memory-decoding or data-routing applications requiring very short propagation delay times. In high-performance systems, these devices can be used to minimize the effects of system decoding. When employed with high-speed memories with a fast enable circuit, the delay times of the decoder and the enable time of the memory are usually less than the typical access time of the memory. The effective system delay introduced by the Schottky-clamped system decoder is negligible.
The conditions at the binary-select (A, B, and C) inputs and the
three enable (G1, 
, and 
) inputs select one of eight output
lines. Two active-low and one active-high 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 SN54ALS138A and SN54AS138 are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS138A and SN74AS138 are characterized for operation from 0°C to 70°C.
| Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | 3-Line To 8-Line Decoders/Demultiplexers datasheet (Rev. E) | 01 Jul 1996 | |
| * | SMD | SN54ALS138A SMD 5962-86866 | 21 Jun 2016 | |
| 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 | Bus-Interface Devices With Output-Damping Resistors Or Reduced-Drive Outputs (Rev. A) | 01 Aug 1997 | ||
| Application note | Designing With Logic (Rev. C) | 01 Jun 1997 | ||
| Application note | Input and Output Characteristics of Digital Integrated Circuits | 01 Oct 1996 | ||
| Application note | Live Insertion | 01 Oct 1996 | ||
| Application note | Advanced Schottky (ALS and AS) Logic Families | 01 Aug 1995 |
For additional terms or required resources, click any title below to view the detail page where available.
| 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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