{"id":6696,"date":"2026-06-19T01:29:24","date_gmt":"2026-06-19T01:29:24","guid":{"rendered":"https:\/\/materialparts.com\/74hct138d\/"},"modified":"2026-06-19T01:29:24","modified_gmt":"2026-06-19T01:29:24","slug":"74hct138d","status":"publish","type":"post","link":"https:\/\/materialparts.com\/ar\/74hct138d\/","title":{"rendered":"74HCT138D"},"content":{"rendered":"

\u0646\u0638\u0631\u0629 \u0639\u0627\u0645\u0629 \u0639\u0644\u0649 \u0627\u0644\u0645\u0646\u062a\u062c<\/h2>\n

The 74HCT138D from Nexperia is a 3-to-8 line decoder\/demultiplexer with TTL-compatible input levels in an SOIC-16 package. It decodes three binary-weighted address inputs (A0-A2) to eight mutually exclusive active-LOW outputs (Y0-Y7). Three enable inputs (E1, E2 active-LOW; E3 active-HIGH) allow easy parallel expansion to 1-of-32 decoding with just four ICs and one inverter.<\/p>\n

\u0627\u0644\u0645\u0648\u0627\u0635\u0641\u0627\u062a \u0627\u0644\u0631\u0626\u064a\u0633\u064a\u0629<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n
Logic Function<\/td>\n3-to-8 line decoder\/demultiplexer (inverting outputs)<\/td>\n<\/tr>\n
\u062c\u0647\u062f \u0627\u0644\u0625\u0645\u062f\u0627\u062f<\/td>\n4.5V to 5.5V (HCT)<\/td>\n<\/tr>\n
\u062a\u0623\u062e\u064a\u0631 \u0627\u0644\u0627\u0646\u062a\u0634\u0627\u0631<\/td>\n19 ns typical @ 5V<\/td>\n<\/tr>\n
Output Drive<\/td>\n\u00b14 mA<\/td>\n<\/tr>\n
Address Inputs<\/td>\n3 (A0, A1, A2)<\/td>\n<\/tr>\n
Outputs<\/td>\n8 (Y0-Y7, active-LOW, mutually exclusive)<\/td>\n<\/tr>\n
Enable Inputs<\/td>\nE1, E2 (active-LOW), E3 (active-HIGH)<\/td>\n<\/tr>\n
Input Levels<\/td>\nTTL (74HCT138)<\/td>\n<\/tr>\n
\u062f\u0631\u062c\u0629 \u062d\u0631\u0627\u0631\u0629 \u0627\u0644\u062a\u0634\u063a\u064a\u0644<\/td>\n-40 \u062f\u0631\u062c\u0629 \u0645\u0626\u0648\u064a\u0629 \u0625\u0644\u0649 +125 \u062f\u0631\u062c\u0629 \u0645\u0626\u0648\u064a\u0629<\/td>\n<\/tr>\n
\u0627\u0644\u062d\u0632\u0645\u0629<\/td>\nSOIC-16 (SOT109-1, 9.9\u00d73.9 mm)<\/td>\n<\/tr>\n<\/table>\n

\u0627\u0644\u0645\u064a\u0632\u0627\u062a<\/h2>\n
    \n
  • Decodes 3 binary inputs to 8 mutually exclusive active-LOW outputs<\/li>\n
  • Three enable inputs for easy cascading and expansion<\/li>\n
  • Expandable to 1-of-32 decoder with four ‘138 ICs + one inverter<\/li>\n
  • Can serve as 1-to-8 demultiplexer using enable as data input<\/li>\n
  • Ideal for memory chip-select decoding<\/li>\n
  • TTL-compatible input levels<\/li>\n
  • Input clamp diodes for overvoltage interface<\/li>\n<\/ul>\n

    \u0627\u0644\u062a\u0637\u0628\u064a\u0642\u0627\u062a<\/h2>\n
      \n
    • Memory chip-select decoding in microprocessor systems<\/li>\n
    • I\/O port address decoding<\/li>\n
    • Data demultiplexing and distribution<\/li>\n
    • 1-of-N decoder expansion in digital systems<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The 74HCT138D from Nexperia is a 3-to-8 line decoder\/demultiplexer with TTL-compatible input levels in an SOIC-16 package. It decodes three binary-weighted address inputs (A0-A2) to eight mutually exclusive active-LOW outputs (Y0-Y7). Three enable inputs (E1, E2 active-LOW; E3 active-HIGH) allow easy parallel expansion to 1-of-32 decoding with just four ICs and one inverter. […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[26,13],"tags":[],"chip_brand":[140],"class_list":["post-6696","post","type-post","status-publish","format-standard","hentry","category-digital-signal-processors-dsp","category-integrated-circuits-ics","chip_brand-nexperia"],"acf":{"brief_explanation":"3-to-8 decoder\/demux, TTL inputs, active-LOW outputs, SOIC-16","date_code":"","package_case":"SOIC-16 \/ SOT109-1 (9.9\u00d73.9\u00d71.45 mm, 1.27mm pitch)","in_stock":9162,"datasheet":"https:\/\/assets.nexperia.com\/documents\/data-sheet\/74HC_HCT138.pdf","price":"$0.14 @ 1ku","product_introduction":"The 74HCT138D from Nexperia is a 3-to-8 line decoder\/demultiplexer with TTL-compatible inputs in an SOIC-16 package. Decoding three address inputs to eight active-LOW mutually exclusive outputs, with three enable inputs for cascading expansion to 1-of-32 decoding. Ideal for memory chip-select decoding, I\/O port addressing, and data demultiplexing in 5V microprocessor systems.","working_principle":"The 74HCT138D decodes three binary-weighted address inputs (A0, A1, A2) to activate one of eight active-LOW outputs (Y0-Y7). The selected output goes LOW while all others remain HIGH. Three enable inputs control the device: E1 and E2 are active-LOW, E3 is active-HIGH. The device is enabled only when E1=LOW, E2=LOW, and E3=HIGH. This triple-enable scheme enables easy cascading; for example, four 74HCT138Ds with a single inverter can create a 5-to-32 line decoder (1-of-32). The device can also function as a 1-to-8 demultiplexer by using one active-LOW enable as a data input and the remaining enables as strobes, routing data to the selected output. The TTL-compatible input stage accepts standard 5V logic levels directly.","pin_description":"\n
      Pin<\/th>Name<\/th>Type<\/th>Function<\/th><\/tr>\n
      1<\/td>A0<\/td>Input<\/td>Address input LSB (TTL level)<\/td><\/tr>\n
      2<\/td>A1<\/td>Input<\/td>Address input<\/td><\/tr>\n
      3<\/td>A2<\/td>Input<\/td>Address input MSB<\/td><\/tr>\n
      4<\/td>E1<\/td>Input<\/td>Enable input (active LOW)<\/td><\/tr>\n
      5<\/td>E2<\/td>Input<\/td>Enable input (active LOW)<\/td><\/tr>\n
      6<\/td>E3<\/td>Input<\/td>Enable input (active HIGH)<\/td><\/tr>\n
      7<\/td>Y7<\/td>Output<\/td>Decoded output (active LOW)<\/td><\/tr>\n
      8<\/td>GND<\/td>Power<\/td>Ground (0V)<\/td><\/tr>\n
      9<\/td>Y6<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      10<\/td>Y5<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      11<\/td>Y4<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      12<\/td>Y3<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      13<\/td>Y2<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      14<\/td>Y1<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      15<\/td>Y0<\/td>Output<\/td>Decoded output<\/td><\/tr>\n
      16<\/td>VCC<\/td>Power<\/td>Supply voltage (4.5-5.5V)<\/td><\/tr>\n<\/table>","application_scenarios":"
        \n
      • Memory chip-select decoding in 5V microprocessor systems<\/li>\n
      • I\/O port address decoding and peripheral selection<\/li>\n
      • Data demultiplexing: routing serial data to one of eight outputs<\/li>\n
      • 1-of-32 decoder expansion using four 74HCT138Ds<\/li>\n<\/ul>","alternative_models":"\n
        Manufacturer<\/th>Part Number<\/th>Package<\/th>Notes<\/th><\/tr>\n
        Nexperia<\/td>74HC138D<\/td>SOIC-16<\/td>CMOS input levels (2.0-6.0V)<\/td><\/tr>\n
        TI<\/td>SN74HCT138DR<\/td>SOIC-16<\/td>Functionally equivalent<\/td><\/tr>\n
        ON Semi<\/td>MC74HCT138ADR2G<\/td>SOIC-16<\/td>Functionally equivalent<\/td><\/tr>\n
        Nexperia<\/td>74HCT138PW<\/td>TSSOP-16<\/td>Smaller footprint<\/td><\/tr>\n
        Nexperia<\/td>74HC238D<\/td>SOIC-16<\/td>Active-HIGH output version<\/td><\/tr>\n<\/table>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/6696","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/comments?post=6696"}],"version-history":[{"count":0,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/6696\/revisions"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/media?parent=6696"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/categories?post=6696"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/tags?post=6696"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/chip_brand?post=6696"}],"curies":[{"name":"\u062f\u0628\u0644\u064a\u0648 \u0628\u064a","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}