{"id":7938,"date":"2026-06-28T05:54:07","date_gmt":"2026-06-28T05:54:07","guid":{"rendered":"https:\/\/materialparts.com\/lm317t-3\/"},"modified":"2026-06-28T11:45:40","modified_gmt":"2026-06-28T11:45:40","slug":"lm317t-3","status":"publish","type":"post","link":"https:\/\/materialparts.com\/ar\/lm317t-3\/","title":{"rendered":"LM317T"},"content":{"rendered":"

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

The LM317T from onsemi\/TI is a 1.5A adjustable positive voltage regulator with output range of 1.25V to 37V, 0.1% line regulation, and 0.1% load regulation in a TO-220 package\u2014the most versatile linear regulator for adjustable power supplies.<\/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\n\n\n\n\n
Output Voltage Range<\/td>\n1.25V to 37V (adjustable)<\/td>\n<\/tr>\n
\u062a\u064a\u0627\u0631 \u0627\u0644\u0625\u062e\u0631\u0627\u062c<\/td>\n1.5A max (with heatsink)<\/td>\n<\/tr>\n
\u0646\u0637\u0627\u0642 \u062c\u0647\u062f \u0627\u0644\u0625\u062f\u062e\u0627\u0644<\/td>\n4.25V to 40V (VOUT + 3V min)<\/td>\n<\/tr>\n
\u062c\u0647\u062f \u0627\u0644\u062a\u0633\u0631\u0628<\/td>\n3V typical @ 1.5A<\/td>\n<\/tr>\n
\u0627\u0644\u062c\u0647\u062f \u0627\u0644\u0645\u0631\u062c\u0639\u064a (VREF)<\/td>\n1.25V typical (1.20V to 1.30V)<\/td>\n<\/tr>\n
Line Regulation<\/td>\n0.01%\/V typical (0.05% max)<\/td>\n<\/tr>\n
Load Regulation<\/td>\n0.1% typical (0.5% max)<\/td>\n<\/tr>\n
Adjust Pin Current<\/td>\n50\u00b5A typical, 100\u00b5A max<\/td>\n<\/tr>\n
Adjust Pin Current Change<\/td>\n0.2\u00b5A typical, 5\u00b5A max<\/td>\n<\/tr>\n
Ripple Rejection<\/td>\n65dB typical @ 120Hz<\/td>\n<\/tr>\n
\u0636\u0648\u0636\u0627\u0621 \u0627\u0644\u0625\u062e\u0631\u0627\u062c<\/td>\n0.003%\/V of output<\/td>\n<\/tr>\n
Thermal Shutdown<\/td>\n~170\u00b0C junction<\/td>\n<\/tr>\n
\u0627\u0644\u062d\u062f \u0627\u0644\u062d\u0627\u0644\u064a<\/td>\n~2.2A typical (internally limited)<\/td>\n<\/tr>\n
\u062f\u0631\u062c\u0629 \u062d\u0631\u0627\u0631\u0629 \u0627\u0644\u062a\u0634\u063a\u064a\u0644<\/td>\n0\u00b0C to +125\u00b0C (junction)<\/td>\n<\/tr>\n
\u0627\u0644\u062d\u0632\u0645\u0629<\/td>\nTO-220-3 (through-hole, tab=VOUT)<\/td>\n<\/tr>\n<\/table>\n

\u0627\u0644\u0645\u064a\u0632\u0627\u062a<\/h2>\n
    \n
  • Adjustable output from 1.25V to 37V<\/li>\n
  • 1.5A output current<\/li>\n
  • Excellent line and load regulation: 0.01%\/V, 0.1%<\/li>\n
  • Internal thermal overload protection<\/li>\n
  • Internal short-circuit current limiting<\/li>\n
  • Output transistor safe operating area protection<\/li>\n
  • Floating operation (can regulate negative voltages)<\/li>\n
  • Only two external resistors set output voltage<\/li>\n<\/ul>\n

    \u0627\u0644\u062a\u0637\u0628\u064a\u0642\u0627\u062a<\/h2>\n
      \n
    • Adjustable bench power supply<\/li>\n
    • Battery charger circuits<\/li>\n
    • Current regulator (constant current source)<\/li>\n
    • Adjustable voltage reference<\/li>\n
    • Lab and test equipment power<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM317T from onsemi\/TI is a 1.5A adjustable positive voltage regulator with output range of 1.25V to 37V, 0.1% line regulation, and 0.1% load regulation in a TO-220 package\u2014the most versatile linear regulator for adjustable power supplies. Key Specifications Output Voltage Range 1.25V to 37V (adjustable) Output Current 1.5A max (with heatsink) Input […]<\/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-7938","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-microcontrollers-processors","chip_brand-ti"],"acf":{"brief_explanation":"1.5A adjustable LDO, 1.25-37V, 0.1% regulation, TO-220","date_code":"","package_case":"TO-220-3 (15.6 x 10.6 x 4.6mm, through-hole, tab=VOUT)","in_stock":25000,"datasheet":"https:\/\/www.onsemi.com\/pub\/Collateral\/LM317-D.PDF","price":"$0.55 @ 1ku","product_introduction":"The LM317T from onsemi\/Texas Instruments is the industry-standard adjustable positive voltage regulator, capable of supplying 1.5A over an output range of 1.25V to 37V. The output voltage is set by just two external resistors: VOUT = 1.25V \u00d7 (1 + R2\/R1) + IADJ \u00d7 R2, where IADJ is typically 50\u00b5A. The 1.25V reference between the output and adjust pins is exceptionally stable, providing 0.01%\/V line regulation and 0.1% load regulation\u2014far better than fixed 78xx regulators. The device is fully floating: it has no ground connection, allowing it to regulate negative voltages when the output is tied to ground. The adjust pin can be bypassed with a capacitor for improved ripple rejection (up to 80dB). The internal protection includes thermal shutdown, current limiting, and safe operating area compensation. The T suffix denotes the TO-220 through-hole package. The LM317 is also commonly used as a constant-current source: connecting the load between the output and adjust pins, with a single resistor from adjust to ground, sets the current to I = 1.25V\/R.","working_principle":"The LM317T maintains a constant 1.25V reference between its output (OUT) and adjust (ADJ) pins. This means that when a resistor R1 is connected between OUT and ADJ, a constant current of I = 1.25V\/R1 flows through R1. This same current (plus the small 50\u00b5A adjust pin current) flows through a second resistor R2 connected from ADJ to ground. The output voltage is VOUT = 1.25V + (1.25V\/R1 + IADJ) \u00d7 R2 = 1.25V \u00d7 (1 + R2\/R1) + IADJ \u00d7 R2. With R1 = 240\u03a9 (standard value), the current through R1 is approximately 5.2mA, which is well above the 3.5mA minimum load current required for regulation. The adjust pin current (50\u00b5A) adds a small error: with R2 = 4.8k\u03a9, IADJ \u00d7 R2 = 0.24V, giving VOUT \u2248 1.25 \u00d7 (1 + 4800\/240) + 0.24 = 26.24V. For a constant-current source, the load is connected between OUT and ADJ (in place of R1), and a single resistor R from ADJ to ground sets the current: I = 1.25V\/R. For 100mA, R = 1.25V\/0.1A = 12.5\u03a9. The 10\u00b5F capacitor on the adjust pin (to ground) improves ripple rejection by bypassing AC signals on the adjust pin, preventing them from modulating the output voltage. The LM317 is a floating regulator: its internal circuitry operates between the input and output pins, with the reference from output to adjust. Since there is no ground connection, the regulator can be used in negative supply configurations by connecting the output to ground and taking the negative output from the input terminal.","pin_description":"\n
      Pin<\/th>Name<\/th>Type<\/th>Description<\/th><\/tr>\n
      1<\/td>ADJ<\/td>Adjustment<\/td>Adjustment pin sets output voltage via external resistor divider. Voltage at this pin is maintained at 1.25V below VOUT by the internal reference. Connect R1 between VOUT and ADJ (typically 240\u03a9), and R2 between ADJ and GND. Output voltage = 1.25V \u00d7 (1 + R2\/R1) + Iadj \u00d7 R2, where Iadj \u2248 50\u00b5A.<\/td><\/tr>\n
      2<\/td>VOUT<\/td>Power Output<\/td>Regulated output voltage from 1.25V to 37V at up to 1.5A. The tab of TO-220 package is electrically connected to VOUT. Bypass with 1\u00b5F solid tantalum or 10\u00b5F electrolytic capacitor to GND. Add protection diode from ADJ to VOUT if output capacitors exceed 10\u00b5F.<\/td><\/tr>\n
      3<\/td>VIN<\/td>Power Input<\/td>Unregulated input voltage. Must be at least Vout + Vdropout (3V typ at 1.5A) for proper regulation. Maximum 40V. Bypass with 0.1\u00b5F ceramic or 1\u00b5F tantalum capacitor to GND when supply is remote. Input voltage must not go negative below -0.7V.<\/td><\/tr>\n<\/table>\n

      LM317T pin assignment (TO-220-3, front view, pins down): Pin 1 (left) = ADJ, Pin 2 (center) = VOUT\/Tab, Pin 3 (right) = VIN. Note the ADJ pin is on the left, unlike fixed 78xx regulators where Input is on the left. The tab is connected to VOUT, not GND. For safe operation with large output capacitors or reverse voltage conditions, add protection diodes: D1 from ADJ to VOUT (1N4001) and D2 from VOUT to VIN (1N5400).<\/p>","application_scenarios":"

        \n
      • Variable PSU:<\/strong> 24V input, R1=240\u03a9, R2=5k\u03a9 pot; VOUT = 1.25-27.5V adjustable; 10\u00b5F cap on ADJ for 80dB ripple rejection<\/li>\n
      • Constant Current:<\/strong> Load between OUT and ADJ; R=12.5\u03a9 from ADJ to GND; I=100mA constant current for LED or battery charging<\/li>\n
      • Battery Charger:<\/strong> LM317 in CC\/CV mode; current limit set by R=1.25V\/0.1A=12.5\u03a9; voltage limit set by R2<\/li>\n
      • 1.25V Reference:<\/strong> ADJ tied to GND; VOUT = 1.25V; 0.1% regulation; replaces zener diode<\/li>\n
      • Negative Supply:<\/strong> OUT tied to GND; input from negative source; ADJ resistor to negative output; floating operation<\/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\/ar\/wp-json\/wp\/v2\/posts\/7938","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=7938"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/7938\/revisions"}],"predecessor-version":[{"id":8231,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/posts\/7938\/revisions\/8231"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/media?parent=7938"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/categories?post=7938"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/tags?post=7938"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/ar\/wp-json\/wp\/v2\/chip_brand?post=7938"}],"curies":[{"name":"\u062f\u0628\u0644\u064a\u0648 \u0628\u064a","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}