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HD74HC149 - 8-to-8-line Priority Encoder

General 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.

Key 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).
  • Ordering Information Part Name Package Type Package Code (Previous Code) Package Abbreviation.

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Datasheet Details

Part number HD74HC149
Manufacturer Renesas
File Size 171.28 KB
Description 8-to-8-line Priority Encoder
Datasheet download datasheet HD74HC149 Datasheet

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Full PDF Text Transcription (Reference)

The following content is an automatically extracted verbatim text from the original manufacturer datasheet and is provided for reference purposes only.

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HD74HC149 8-to-8-line Priority Encoder REJ03D0574-0200 (Previous ADE-205-448) Rev.2.00 Oct 11, 2005 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 - Y7) is low, P output is low and this indicates active condition.