onsemi MC74AC138MR1

The MC74AC138/74ACT138 is a high−speed 1−of−8 decoder/demultiplexer. This device is ideally suited for high−speed bipolar memory chip select address decoding. The multiple input enables allow parallel expansion to a 1−of−24 decoder using just three MC74AC138/74ACT138 devices or a 1−of−32 decoder using four MC74AC138/74ACT138 devices and one inverter. The MC74AC138/74ACT138 high−speed 1−of−8 decoder/demultiplexer accepts three binary weighted inputs (A0, A1, A2) and, when enabled, provides eight mutually exclusive active−LOW outputs (Ω0(overline) - Ω7(overline)). The MC74AC138/74ACT138 features three Enable inputs, two active−LOW (E1(overline), E2(overline)) and one active−HIGH (E3). All outputs will be HIGH unless E1(overline) and E2(overline) are LOW and E3 is HIGH. This multiple enabled function allows easy parallel expansion of the device to a 1−of−32 (5 lines to 32 lines) decoder with just four MC74AC138/74ACT138 devices and one inverter. The MC74AC138/74ACT138 can be used as an 8−output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes. The Enable inputs which are not used must be permanently tied to their appropriate active−HIGH or active−LOW state.

• Demultiplexing Capability
• Multiple Input Enable for Easy Expansion
• Active LOW Mutually Exclusive Outputs
• Outputs Source/Sink 24 mA
• ′ACT138 Has TTL Compatible Inputs
• These devices are available in Pb−free package(s)