{"id":3196,"date":"2026-05-31T03:20:38","date_gmt":"2026-05-31T03:20:38","guid":{"rendered":"https:\/\/materialparts.com\/lm1085isx-3-3\/"},"modified":"2026-06-06T03:28:51","modified_gmt":"2026-06-06T03:28:51","slug":"lm1085isx-3-3","status":"publish","type":"post","link":"https:\/\/materialparts.com\/zh\/lm1085isx-3-3\/","title":{"rendered":"LM1085ISX-3.3"},"content":{"rendered":"

\u4ea7\u54c1\u6982\u89c8<\/h2>\n

The LM1085ISX-3.3 from Texas Instruments is a 3 A low-dropout positive voltage regulator with a fixed 3.3 V output. It features a maximum dropout voltage of 1.5 V at 3 A load current, current limiting, and thermal shutdown protection. The device is available in a TO-263 (D2PAK) surface-mount package for the ISX tape-and-reel variant.<\/p>\n

\u4e3b\u8981\u89c4\u683c<\/h2>\n\n\n\n\n\n\n\n\n\n
Output Voltage<\/td>\n3.3 V (fixed)<\/td>\n<\/tr>\n
\u8f93\u51fa\u7535\u6d41<\/td>\n3 A<\/td>\n<\/tr>\n
Dropout Voltage<\/td>\n1.3 V typical, 1.5 V max @ 3 A<\/td>\n<\/tr>\n
\u8f93\u5165\u7535\u538b\u8303\u56f4<\/td>\n4.8 V to 27 V<\/td>\n<\/tr>\n
Line Regulation<\/td>\n0.015% typical<\/td>\n<\/tr>\n
Load Regulation<\/td>\n0.1% typical<\/td>\n<\/tr>\n
PSRR<\/td>\n72 dB at 120 Hz<\/td>\n<\/tr>\n
\u5de5\u4f5c\u6e29\u5ea6<\/td>\n-40\u00b0C to 125\u00b0C<\/td>\n<\/tr>\n<\/table>\n

\u7279\u70b9<\/h2>\n
    \n
  • 3 A output current capability<\/li>\n
  • Low dropout voltage: 1.3 V typical at 3 A<\/li>\n
  • Fixed 3.3 V output with +\/-1% accuracy<\/li>\n
  • Line regulation: 0.015% typical<\/li>\n
  • Load regulation: 0.1% typical<\/li>\n
  • Internal current limiting and thermal shutdown<\/li>\n
  • Zener trimmed bandgap reference<\/li>\n
  • TO-263 surface-mount package<\/li>\n<\/ul>\n

    \u5e94\u7528<\/h2>\n
      \n
    • 3.3 V logic power supply regulation<\/li>\n
    • Post-regulation for switching power supplies<\/li>\n
    • Battery-powered systems and chargers<\/li>\n
    • Embedded processor and FPGA core power<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM1085ISX-3.3 from Texas Instruments is a 3 A low-dropout positive voltage regulator with a fixed 3.3 V output. It features a maximum dropout voltage of 1.5 V at 3 A load current, current limiting, and thermal shutdown protection. The device is available in a TO-263 (D2PAK) surface-mount package for the ISX tape-and-reel […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,32],"tags":[],"chip_brand":[138],"class_list":["post-3196","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-low-dropout-regulators-ldo","chip_brand-ti"],"acf":{"brief_explanation":"3 A LDO regulator, 3.3 V fixed output, 1.3 V dropout, TO-263, thermal protection","date_code":"","package_case":"TO-263-3 (D2PAK, 10.16 x 8.64 mm)","in_stock":7600,"datasheet":"https:\/\/www.ti.com\/lit\/ds\/symlink\/lm1085.pdf","price":"$0.79 @ 1ku","product_introduction":"The LM1085ISX-3.3 is a 3 A low-dropout (LDO) positive voltage regulator from Texas Instruments, providing a fixed 3.3 V output with excellent line and load regulation. With a maximum dropout voltage of only 1.5 V at the full 3 A load, the device can maintain regulation with an input as low as 4.8 V, making it ideal for 5 V to 3.3 V conversion in mixed-voltage systems. The regulator features a zener-trimmed bandgap reference that ensures output voltage accuracy within +\/-1%. Internal current limiting protects against output short circuits, while thermal shutdown prevents damage from excessive junction temperature. The TO-263 (D2PAK) surface-mount package provides excellent thermal performance with a junction-to-case thermal resistance that supports the full 3 A output without an external heatsink in many applications. The ISX variant is supplied on tape and reel for automated assembly.","working_principle":"The LM1085ISX-3.3 operates as a series pass regulator with three key control loops: (1) The voltage regulation loop compares a fraction of the output voltage (sensed through an internal resistor divider for the fixed-voltage version) with the bandgap reference voltage. The error amplifier adjusts the pass transistor gate drive to maintain the output at the target 3.3 V. The zener-trimmed bandgap reference provides high accuracy and low temperature drift. (2) The current limiting circuit monitors the current through the pass transistor and limits it to a safe value when an overload or short circuit occurs, protecting both the regulator and the load. (3) The thermal shutdown circuit monitors the junction temperature and turns off the pass transistor when the temperature exceeds approximately 165\u00b0C, preventing thermal damage. The regulator recovers automatically when the junction cools below the hysteresis threshold. The low dropout voltage is achieved by using a PNP pass transistor structure that can saturate with minimal VCE saturation voltage.","pin_description":"
      Pin No.<\/td>Pin Name<\/td>Function<\/td><\/tr>
      1<\/td>ADJ\/GND<\/td>Ground (for fixed-voltage version)<\/td><\/tr>
      2<\/td>VOUT<\/td>Regulated 3.3 V output<\/td><\/tr>
      3<\/td>VIN<\/td>Unregulated input supply (4.8 V to 27 V)<\/td><\/tr>
      Tab<\/td>VOUT<\/td>Output (connected to pin 2 internally)<\/td><\/tr><\/table>","application_scenarios":"
      • 5 V to 3.3 V conversion for microcontrollers, FPGAs, and digital logic in embedded systems<\/li>
      • Post-regulation of switching power supply outputs where low noise and high PSRR (72 dB) are required<\/li>
      • Battery-powered devices needing efficient regulation from 5 V or 6 V battery packs to 3.3 V logic rails<\/li>
      • Industrial control systems requiring robust thermal and overcurrent protection in a surface-mount package<\/li><\/ul>","alternative_models":"
        Model<\/td>Brand<\/td>Output<\/td>Max Current<\/td>Dropout<\/td><\/tr>
        LM1085ISX-5.0<\/td>TI<\/td>5.0 V<\/td>3 A<\/td>1.5 V<\/td><\/tr>
        LM1085ISX-ADJ<\/td>TI<\/td>Adjustable<\/td>3 A<\/td>1.5 V<\/td><\/tr>
        LM1084ISX-3.3<\/td>TI<\/td>3.3 V<\/td>5 A<\/td>1.3 V<\/td><\/tr>
        AMS1117-3.3<\/td>Advanced Monolithic<\/td>3.3 V<\/td>1 A<\/td>1.1 V<\/td><\/tr>
        LD1117S33TR<\/td>ST<\/td>3.3 V<\/td>0.8 A<\/td>1.1 V<\/td><\/tr><\/table>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/3196","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/comments?post=3196"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/3196\/revisions"}],"predecessor-version":[{"id":3277,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/3196\/revisions\/3277"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/media?parent=3196"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/categories?post=3196"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/tags?post=3196"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/chip_brand?post=3196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}