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HD74HC149 - 8-to-8-line Priority Encoder

Description

The HD74HC149 is priority encoder which has 8 input lines (0 - 7) and 8 output lies (Y0 - Y7).

It is the logical combination of a HD74HC148 8-3 line priority encoder driving a HD74HC138 3-8 line decoder.

Only one request output can be low at a time.

Features

  • High Speed Operation: tpd (0 - 7 to Y) = 16 ns typ (CL = 50 pF) High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 2 to 6 V Low Input Current: 1 µA max Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C) HD74HC149 Function Table Inputs 0 X H X X X X X X X L H : L : X : 1 X H X X X X X X L H 2 X H X X X X X L H H 3 X H X X X X L H H H 4 X H X X X L H H H H 5 X H X X L H H H H H 6 X H X L H H H H H H 7 X H L.

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📁 Similar Datasheet

Part Number Description Manufacturer
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Part Number Description
HD74HC14 Hex Schmitt-trigger Inverters
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Full PDF Text Transcription

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HD74HC149 8-to-8-line Priority Encoder Description The HD74HC149 is priority encoder which has 8 input lines (0 - 7) and 8 output lies (Y0 - Y7). It is the logical combination of a HD74HC148 8-3 line priority encoder driving a HD74HC138 3-8 line decoder. Only one request output can be low at a time. The output that is low is dependent on the highest priority request that is low. The order of priority is 7 highest and 0 lowest. When E input is high, all outputs are high. When a output (Y0 - Y 7) is low, P output is low and this indicates active condition.
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