描述 Description

The Harris CD74HC139, CD74HCT139 contain two independent binary to one of four decoders each with a single active low enable input (1E or 2E). Data on the select inputs (1A0 and 1A1 or 2A0 and 2A1) cause one of the four normally high outputs to go low.

If the enable input is high all four outputs remain high. For demultiplexer operation the enable input is the data input. The enable input also functions as a chip select when these devices are cascaded. This device is functionally the same as the CD4556B and is pin compatible with it.

The outputs of these devices can drive 10 low power Schottky TTL equivalent loads. The 74HCT logic family is functionally as well as pin equivalent to the 74LS logic family.

特性 Features

? Multifunction Capability

- Binary to 1 of 4 Decoders or 1 to 4 Line Demultiplexer

? Active Low Mutually Exclusive Outputs

? Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

? Wide Operating Temperature Range . . . -55°C to 125°C

? Balanced Propagation Delay and Transition Times

? Significant Power Reduction Compared to LSTTL Logic ICs

? HC Types

- 2V to 6V Operation

- High Noise Immunity: NIL = 30, NIH = 30of VCC at VCC = 5V

? HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility, VIL= 0.8V (Max), VIH = 2V (Min)

- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

? Memory Decoding, Data Routing, Code Conversion