The MC74HC138A is identical in pinout to the LS138. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LSTTL outputs. The HC138A decodes a three−bit Address to one−of−eight active−low outputs. This device features three Chip Select inputs, two active−low and one active−high to facilitate the demultiplexing, cascading, and chip−selecting functions. The demultiplexing function is accomplished by using the Address inputs to select the desired device output; one of the Chip Selects is used as a data input while the other Chip Selects are held in their active states.

FEATUREs
• Output Drive Capability: 10 LSTTL Loads
• Outputs Directly Interface to CMOS, NMOS and TTL
• Operating Voltage Range: 2.0 to 6.0 V
• Low Input Current: 1.0 A
• High Noise Immunity Characteristic of CMOS Devices
• In Compliance with the Requirements Defined by JEDEC Standard No. 7A
• Chip Complexity: 100 FETs or 29 Equivalent Gates
• Pb−Free Packages are Available*