MC74ACT138DR2

The MC74ACT138DR2 from On Semiconductor is a high-speed 1-of-8 decoder/demultiplexer designed for applications such as high-speed bipolar memory chip select address decoding. This device accepts three binary weighted inputs (A0, A1, A2) and provides eight mutually exclusive active-LOW outputs (O0-O7) when enabled.

It features three enable inputs: two active-LOW (E1, E2) and one active-HIGH (E3). All outputs remain HIGH unless E1 and E2 are LOW and E3 is HIGH. This configuration allows for easy parallel expansion to create larger decoders, such as a 1-of-32 decoder using four MC74ACT138DR2 devices and one inverter.

The MC74ACT138DR2 is suitable for use as an 8-output demultiplexer by utilizing one active-LOW enable input as the data input and the others as strobes. Unused enable inputs must be tied to their appropriate active-HIGH or active-LOW state. The device operates from a single supply voltage of 4.5V to 5.5V and has an operating temperature range of -40°C to 85°C.

Packaged in a 16-SOIC (0.154", 3.90mm Width) surface-mount case, this decoder/demultiplexer is designed for efficient integration into various electronic circuits. Its outputs can source or sink up to 24 mA.