Controlled Baseline
– One Assembly/Test Site, One Fabrication
Site
Extended Temperature Performance of
–55°C to 125°C
Enhanced Diminishing Manufacturing
Sources (DMS) Support
Enhanced Product-Change Notification
Qualification Pedigree†
EPIC (Enhanced-Performance Implanted
CMOS) Process
Inputs Are TTL-Voltage Compatible
Designed Specifically for High-Speed
Memory Decoders and Data-Transmission
Systems
Incorporates Three Enable Inputs to
Simplify Cascading and/or Data Reception
Latch-Up Performance Exceeds 250 mA Per
JESD 17
ESD Protection Exceeds 2000 V Per
MIL-STD-833, Method 3015; Exceeds 200 V
Using Machine Model (C = 200 pF, R = 0)

description/ordering information
The SN74AHCT138 3-line to 8-line decoder/demultiplexer is designed to be used in high-performance
memory-decoding and data-routing applications that require very short propagation-delay times. In
high-performance memory systems, this decoder can be used to minimize the effects of system decoding.
When employed with high-speed memories utilizing a fast enable circuit, the delay times of this decoder 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 decoder is negligible.
The conditions at the binary-select inputs and the three enable 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.