{"id":7898,"date":"2026-06-28T03:26:43","date_gmt":"2026-06-28T03:26:43","guid":{"rendered":"https:\/\/materialparts.com\/lm317t-2\/"},"modified":"2026-06-28T11:46:28","modified_gmt":"2026-06-28T11:46:28","slug":"lm317t-2","status":"publish","type":"post","link":"https:\/\/materialparts.com\/es\/lm317t-2\/","title":{"rendered":"LM317T"},"content":{"rendered":"

Productos<\/h2>\n

The LM317T is a 1.5A adjustable positive linear voltage regulator from Texas Instruments, providing output from 1.25V to 37V with only two external resistors, in a TO-220-3 through-hole package.<\/p>\n

Especificaciones<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Output Voltage Range<\/td>\n1.25V to 37V (adjustable)<\/td>\n<\/tr>\n
Corriente de salida<\/td>\n1.5A (max)<\/td>\n<\/tr>\n
Input Voltage Range<\/td>\n4.25V to 40V<\/td>\n<\/tr>\n
Line Regulation<\/td>\n0.01%\/V typical<\/td>\n<\/tr>\n
Load Regulation<\/td>\n0.1% typical<\/td>\n<\/tr>\n
Ripple Rejection<\/td>\n80dB (120Hz)<\/td>\n<\/tr>\n
Reference Voltage<\/td>\n1.25V (between OUT and ADJ)<\/td>\n<\/tr>\n
Dropout Voltage<\/td>\n3V typical (VI-VO minimum)<\/td>\n<\/tr>\n
Thermal Overload Protection<\/td>\nYes<\/td>\n<\/tr>\n
Short-Circuit Protection<\/td>\nYes (current limit constant with temperature)<\/td>\n<\/tr>\n
Safe Operating Area Protection<\/td>\nYes<\/td>\n<\/tr>\n
Temperatura de funcionamiento<\/td>\n0\u00b0C to +125\u00b0C<\/td>\n<\/tr>\n
Paquete<\/td>\nTO-220-3 (14.986 x 10.16mm, through-hole)<\/td>\n<\/tr>\n<\/table>\n

Caracter\u00edsticas<\/h2>\n
    \n
  • Adjustable output from 1.25V to 37V with two external resistors<\/li>\n
  • 1.5A output current capability<\/li>\n
  • 0.1% typical load regulation<\/li>\n
  • 0.01%\/V typical line regulation<\/li>\n
  • 80dB ripple rejection at 120Hz<\/li>\n
  • Thermal overload, short-circuit, and SOA protection<\/li>\n
  • Floating architecture for high-voltage regulation<\/li>\n
  • Can be used as a precision current regulator<\/li>\n
  • Electronic shutdown by clamping ADJ to ground<\/li>\n<\/ul>\n

    Aplicaciones<\/h2>\n
      \n
    • Adjustable bench power supplies<\/li>\n
    • Battery chargers and charging circuits<\/li>\n
    • Current regulator for LED strings<\/li>\n
    • Local on-card regulation<\/li>\n
    • High-voltage regulators (floating operation)<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM317T is a 1.5A adjustable positive linear voltage regulator from Texas Instruments, providing output from 1.25V to 37V with only two external resistors, in a TO-220-3 through-hole package. Key Specifications Output Voltage Range 1.25V to 37V (adjustable) Output Current 1.5A (max) Input Voltage Range 4.25V to 40V Line Regulation 0.01%\/V typical Load […]<\/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":[13,24],"tags":[],"chip_brand":[138],"class_list":["post-7898","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-microcontrollers-processors","chip_brand-ti"],"acf":{"brief_explanation":"1.5A adj positive regulator, 1.25-37V out, 80dB PSRR, TO-220-3","date_code":"","package_case":"TO-220-3 (14.986 x 10.16 x 4.6mm, 2.54mm pitch, through-hole)","in_stock":25000,"datasheet":"https:\/\/www.ti.com\/lit\/ds\/symlink\/lm317-n.pdf","price":"$0.76 @ 1ku","product_introduction":"The LM317T from Texas Instruments is a classic adjustable 3-terminal positive voltage regulator capable of supplying more than 1.5A over an output range of 1.25V to 37V. It requires only two external resistors to set the output voltage: VOUT = 1.25V \u00d7 (1 + R2\/R1) + IADJ \u00d7 R2, where IADJ is typically 50\u00b5A. The device offers superior line and load regulation compared to fixed regulators (0.01%\/V and 0.1% typical, respectively) and 80dB ripple rejection. Full overload protection includes current limiting, thermal shutdown, and safe operating area protection\u2014all of which remain functional even if the ADJ pin is accidentally disconnected. The floating architecture means the regulator only sees the input-to-output differential voltage, allowing it to regulate supplies of several hundred volts as long as the differential does not exceed 40V. The T suffix denotes the TO-220-3 through-hole package, ideal for heatsink mounting.","working_principle":"The LM317T maintains a constant 1.25V reference between the OUT and ADJ pins. Current flowing through R1 (connected between OUT and ADJ) is I_R1 = 1.25V \/ R1. This same current (plus the small IADJ of ~50\u00b5A) flows through R2 (connected between ADJ and GND), setting the output voltage: VOUT = 1.25V \u00d7 (1 + R2\/R1) + IADJ \u00d7 R2. For practical purposes, IADJ \u00d7 R2 is negligible, so VOUT \u2248 1.25V \u00d7 (1 + R2\/R1). A typical design uses R1 = 240\u03a9, giving I_R1 \u2248 5.2mA. The output voltage is then set by R2: for 5V output, R2 \u2248 720\u03a9; for 12V, R2 \u2248 2.06k\u03a9; for 3.3V, R2 \u2248 394\u03a9. The minimum load current is approximately 3.5mA (the internal reference current), so R1 should not exceed approximately 375\u03a9 to guarantee regulation under no-load conditions. The input-to-output differential voltage must be at least 3V (dropout voltage) for proper regulation, meaning VIN must be at least VOUT + 3V. The internal current limit is typically 2.2A at 25\u00b0C, and it remains relatively constant over temperature. The thermal shutdown activates at approximately 170\u00b0C junction temperature. The ADJ pin can be bypassed with a 10\u00b5F capacitor to improve ripple rejection to over 80dB.","pin_description":"\n
      Pin<\/th>Name<\/th>Type<\/th>Description<\/th><\/tr>\n
      1<\/td>ADJ<\/td>Input<\/td>Adjust pin (connect R1 to OUT, R2 to GND)<\/td><\/tr>\n
      2<\/td>OUT<\/td>Output<\/td>Regulated output voltage (1.25V to 37V)<\/td><\/tr>\n
      3<\/td>IN<\/td>Input<\/td>Unregulated input voltage (4.25V to 40V)<\/td><\/tr>\n<\/table>\n

      LM317T uses the TO-220-3 package with adjustable regulator pinout: Pin 1 = ADJ (Adjustment), Pin 2 = VOUT (tab), Pin 3 = VIN. This pinout differs from fixed 78xx regulators where Pin 1 = INPUT. The tab is electrically connected to VOUT (Pin 2), not GND \u2014 this is critical for heatsink mounting. When VOUT is not at ground potential, an insulating washer is required between tab and heatsink. The ADJ pin maintains 1.25V below VOUT with 50\u00b5A bias current. Output voltage is set by R1 (VOUT to ADJ, typically 240\u03a9) and R2 (ADJ to GND). Protection diodes are recommended: D1 (1N4002, ADJ to VOUT) for output capacitors >10\u00b5F, and D2 (1N5400, VIN to VOUT) for reverse input conditions.<\/p>","application_scenarios":"

        \n
      • Adjustable Bench PSU:<\/strong> Replace R2 with a 5k\u03a9 potentiometer for 1.25V\u201326V adjustable output; add 10\u00b5F cap on ADJ for clean output<\/li>\n
      • Battery Charger:<\/strong> Set VOUT to float voltage (e.g., 13.8V for 12V lead-acid); add series diode and current-limiting resistor<\/li>\n
      • LED Current Regulator:<\/strong> Connect ADJ to load (LED cathode) with R1 setting ILED = 1.25V \/ R1; e.g., R1=12.5\u03a9 gives 100mA<\/li>\n
      • High-Voltage Regulation:<\/strong> Floating topology allows regulating 100V+ rails; only VI-VO differential must stay under 40V<\/li>\n
      • Electronic Shutdown:<\/strong> Drive ADJ to GND with a transistor; VOUT drops to 1.25V where most loads draw negligible current<\/li>\n<\/ul>","alternative_models":"\n
        Model<\/th>Manufacturer<\/th>Key Difference<\/th>Package<\/th>Specs<\/th><\/tr>\n
        LM317AT<\/td>onsemi<\/td>Tighter reference voltage tolerance \u00b11% vs \u00b14% for precision adjustable power supplies<\/td>TO-220-3<\/td>1.25-37V\/1.5A<\/td><\/tr>\n
        LM317EMP\/NOPB<\/td>TI<\/td>SOT-223 surface-mount version for compact board designs with 1A output current<\/td>SOT-223-4<\/td>1.25-37V\/1A<\/td><\/tr>\n
        LM317DCYT\/NOPB<\/td>TI<\/td>SOT-223-3 with TO-263 compatibility and lower dropout for space-constrained designs<\/td>SOT-223-3<\/td>1.25-37V\/1A<\/td><\/tr>\n
        LM337T<\/td>TI<\/td>Negative adjustable complement: -1.25V to -37V for symmetric split-rail power supplies<\/td>TO-220-3<\/td>-1.25 to -37V\/1.5A<\/td><\/tr>\n
        LM1117MP-3.3<\/td>TI<\/td>Lower dropout (1.1V) fixed 3.3V alternative for regulated 3.3V logic supply rails<\/td>SOT-223-4<\/td>3.3V\/800mA LDO<\/td><\/tr>\n
        LM1085IT-5.0<\/td>TI<\/td>3A higher-current adjustable LDO for applications requiring more than 1.5A output<\/td>TO-220-3<\/td>1.25-37V\/3A<\/td><\/tr>\n<\/table>\n

        LM317T is a 1.25-37V adjustable positive voltage regulator in TO-220-3 with 1.5A output and \u00b14% reference tolerance. The LM317AT offers \u00b11% precision. For surface-mount, use LM317EMP (SOT-223). For higher current, LM1085 provides 3A output. The LM337T is the negative complement for split-rail supplies. All require only two external resistors to set output voltage.<\/p>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/posts\/7898","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/comments?post=7898"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/posts\/7898\/revisions"}],"predecessor-version":[{"id":8250,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/posts\/7898\/revisions\/8250"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/media?parent=7898"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/categories?post=7898"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/tags?post=7898"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/es\/wp-json\/wp\/v2\/chip_brand?post=7898"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}