NXP 74HCT138D 芯片, 74HCT CMOS逻辑器件
The is a 3-to-8 inverting Decoder/Demultiplexer decodes three binary weighted address inputs A0, A1 and A2 to eight mutually exclusive outputs Y0\ to Y7\\. The device features three enable inputs E1\, E2\ and E3. Every output will be high unless E1\ and E2\ are low and E3 is high. This multiple enable function allows easy parallel expansion to a 1-of-32 5 to 32 lines decoder with just four 138 series ICs and one inverter. The 138 series can be used as an eight output demultiplexer by using one of the active low enable inputs as the data input and the remaining enable inputs as strobes. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC.