{"id":7930,"date":"2026-06-28T05:53:57","date_gmt":"2026-06-28T05:53:57","guid":{"rendered":"https:\/\/materialparts.com\/lm7812ct-2\/"},"modified":"2026-06-28T11:45:53","modified_gmt":"2026-06-28T11:45:53","slug":"lm7812ct-2","status":"publish","type":"post","link":"https:\/\/materialparts.com\/zh\/lm7812ct-2\/","title":{"rendered":"LM7812CT"},"content":{"rendered":"

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

The LM7812CT from onsemi is a 3-terminal 1A positive voltage regulator providing a fixed 12V output with internal thermal overload protection, short-circuit protection, and output transistor safe operating area compensation in a TO-220 package.<\/p>\n

\u4e3b\u8981\u89c4\u683c<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Output Voltage<\/td>\n12V fixed (\u00b12% at 25\u00b0C for A-grade)<\/td>\n<\/tr>\n
\u8f93\u51fa\u7535\u6d41<\/td>\n1A (up to 1.5A with heatsink)<\/td>\n<\/tr>\n
\u8f93\u5165\u7535\u538b\u8303\u56f4<\/td>\n14.5V to 27V (14.5V min for regulation)<\/td>\n<\/tr>\n
Maximum Input Voltage<\/td>\n35V<\/td>\n<\/tr>\n
Dropout Voltage<\/td>\n2V typical @ 1A<\/td>\n<\/tr>\n
Line Regulation<\/td>\n10mV typical (14.8V to 27V, IO=500mA)<\/td>\n<\/tr>\n
Load Regulation<\/td>\n12mV typical (5mA to 1A)<\/td>\n<\/tr>\n
\u9759\u6001\u7535\u6d41<\/td>\n6mA typical<\/td>\n<\/tr>\n
Ripple Rejection<\/td>\n61dB typical @ 120Hz<\/td>\n<\/tr>\n
Output Noise Voltage<\/td>\n75\u00b5V typical (10Hz to 100kHz)<\/td>\n<\/tr>\n
Short-Circuit Current<\/td>\n1.5A typical<\/td>\n<\/tr>\n
Peak Output Current<\/td>\n2.4A typical<\/td>\n<\/tr>\n
Thermal Shutdown<\/td>\n~170\u00b0C junction<\/td>\n<\/tr>\n
\u5de5\u4f5c\u6e29\u5ea6<\/td>\n-40\u00b0C to +125\u00b0C (junction)<\/td>\n<\/tr>\n
\u5305\u88c5<\/td>\nTO-220-3 (through-hole, tab=GND)<\/td>\n<\/tr>\n<\/table>\n

\u7279\u70b9<\/h2>\n
    \n
  • Fixed 12V output with \u00b12% tolerance<\/li>\n
  • 1A continuous output current<\/li>\n
  • Internal thermal overload protection<\/li>\n
  • Internal short-circuit current limiting<\/li>\n
  • Output transistor safe operating area protection<\/li>\n
  • High ripple rejection: 61dB at 120Hz<\/li>\n
  • Only two external capacitors needed<\/li>\n<\/ul>\n

    \u5e94\u7528<\/h2>\n
      \n
    • 12V power supply regulation<\/li>\n
    • Analog circuit power rails<\/li>\n
    • Relay and solenoid driver supply<\/li>\n
    • Post-regulator after switching supply<\/li>\n
    • Automotive 12V systems<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM7812CT from onsemi is a 3-terminal 1A positive voltage regulator providing a fixed 12V output with internal thermal overload protection, short-circuit protection, and output transistor safe operating area compensation in a TO-220 package. Key Specifications Output Voltage 12V fixed (\u00b12% at 25\u00b0C for A-grade) Output Current 1A (up to 1.5A with heatsink) […]<\/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-7930","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-microcontrollers-processors","chip_brand-ti"],"acf":{"brief_explanation":"12V 1A positive linear regulator, TO-220, thermal\/short-circuit protection","date_code":"","package_case":"TO-220-3 (15.6 x 10.6 x 4.6mm, through-hole, tab=GND)","in_stock":21000,"datasheet":"https:\/\/www.onsemi.com\/pub\/Collateral\/LM78XX-D.PDF","price":"$0.52 @ 1ku","product_introduction":"The LM7812CT from onsemi (formerly Fairchild\/National Semiconductor) is a 3-terminal positive voltage regulator providing a fixed 12V output at up to 1A load current. It is part of the ubiquitous 78xx series that has been the backbone of linear power supply design for decades. The device requires only two external capacitors (0.33\u00b5F input, 0.1\u00b5F output) for stable operation. Internal protection includes thermal shutdown (disables output at ~170\u00b0C junction), current limiting (short-circuit current limited to ~1.5A), and safe operating area compensation (reduces current limit as input-output differential increases). The 2V dropout voltage means the input must be at least 14V to maintain 12V output at full load. The 61dB ripple rejection at 120Hz makes it effective for cleaning up rectified AC or noisy switching supply outputs. The CT suffix denotes the TO-220 package with commercial\/industrial temperature range. Note: DigiKey lists this part as obsolete; the MC7812CTG from onsemi is the current production equivalent.","working_principle":"The LM7812CT uses a series pass transistor (NPN Darlington) between the input and output, controlled by a feedback loop that compares a fraction of the output voltage with an internal bandgap reference. The error amplifier drives the pass transistor to maintain VOUT = 12V. When the output voltage drops below 12V (due to increased load or decreased input), the error amplifier increases the drive to the pass transistor, increasing current flow and raising the output voltage. When the output rises above 12V, the drive is reduced. The thermal protection circuit uses a temperature sensor on the die; when junction temperature exceeds approximately 170\u00b0C, the pass transistor is disabled until the device cools to a safe temperature. The current limiting circuit monitors the pass transistor current; when it exceeds approximately 1.5A at low input-output differential, the drive is limited to prevent damage. The safe operating area (SOA) protection further reduces the current limit as the input-output voltage differential increases, keeping the pass transistor within its safe operating region. The 6mA quiescent current flows through the ground pin and provides bias for the internal reference and error amplifier. The 0.33\u00b5F input capacitor prevents oscillation when the input source has high impedance, and the 0.1\u00b5F output capacitor improves transient response.","pin_description":"\n
      Pin<\/th>Name<\/th>Type<\/th>Description<\/th><\/tr>\n
      1<\/td>INPUT<\/td>Power Input<\/td>Unregulated input voltage. Must be at least 3.7V (Vout + Vdropout \u2248 3.7V) for proper regulation. Maximum 35V. Bypass with 0.33\u00b5F ceramic capacitor to GND if supply is more than 6 inches from the regulator.<\/td><\/tr>\n
      2<\/td>GND<\/td>Ground<\/td>Common ground reference. The TO-220 tab is electrically connected to this pin and serves as the primary heat dissipation path. Use thermal compound and heatsink for currents above 500mA.<\/td><\/tr>\n
      3<\/td>OUTPUT<\/td>Power Output<\/td>Regulated 1.2V DC output at up to 1A continuous current with \u00b14% tolerance. Bypass with 0.1\u00b5F ceramic capacitor to GND to improve transient response and output impedance. Do not apply external voltage higher than 1.2V to prevent reverse bias damage.<\/td><\/tr>\n<\/table>\n

      Pin assignment follows standard TO-220-3 layout: Pin 1 (left) = Input, Pin 2 (center) = Ground\/Tab, Pin 3 (right) = Output, when viewed from the front with pins pointing down. The metal tab on the back is electrically connected to Pin 2 (GND) and must be insulated from the heatsink when the heatsink is not at ground potential. Output capacitance of 0.1\u00b5F is required for stability; input capacitance of 0.33\u00b5F is recommended when the input supply is remote.<\/p>","application_scenarios":"

        \n
      • 12V Bench Supply:<\/strong> 18V AC transformer \u2192 bridge rectifier \u2192 2200\u00b5F filter \u2192 LM7812CT; 12V regulated output at up to 1A<\/li>\n
      • Post-SMPS Regulator:<\/strong> 15V switching supply \u2192 LM7812CT; 61dB ripple rejection cleans switcher noise; Pdiss = (15-12)\u00d71A = 3W<\/li>\n
      • Automotive 12V:<\/strong> 14.4V car battery \u2192 LM7812CT; stable 12V for analog circuits despite battery voltage variation<\/li>\n
      • Split Supply:<\/strong> LM7812CT (+12V) + LM7912CT (-12V) from center-tapped transformer; \u00b112V for op-amp circuits<\/li>\n
      • Adjustable Output:<\/strong> LM7812CT with external op-amp and resistor divider to set output above 12V (e.g., 13.8V for battery charging)<\/li>\n<\/ul>","alternative_models":"\n
        Model<\/th>Manufacturer<\/th>Key Difference<\/th>Package<\/th>Specs<\/th><\/tr>\n
        LM7812ACT<\/td>onsemi<\/td>Tighter output tolerance: \u00b12% vs \u00b14% for precision power supply applications<\/td>TO-220-3<\/td>1.2V\/1A<\/td><\/tr>\n
        L7812CV<\/td>STMicroelectronics<\/td>Direct equivalent with 1.5A output current, internal thermal shutdown and current limiting<\/td>TO-220-3<\/td>1.2V\/1.5A<\/td><\/tr>\n
        MC7812CTG<\/td>onsemi<\/td>Current production replacement with identical electrical specifications and RoHS compliance<\/td>TO-220-3<\/td>1.2V\/1A<\/td><\/tr>\n
        KA7812<\/td>onsemi\/Fairchild<\/td>Budget-friendly version with \u00b14% tolerance and standard 1A output current rating<\/td>TO-220-3<\/td>1.2V\/1A<\/td><\/tr>\n
        MC7812ABD2TG<\/td>onsemi<\/td>Surface-mount DPAK version with \u00b12% A-grade tolerance for compact PCB layouts<\/td>DPAK-3<\/td>1.2V\/1A<\/td><\/tr>\n
        LM2940CT-1.2<\/td>TI<\/td>Low-dropout version with 0.5V max dropout at 1A for battery-powered and automotive systems<\/td>TO-220-3<\/td>1.2V\/1A LDO<\/td><\/tr>\n<\/table>\n

        LM7812CT is a 1.2V fixed positive voltage regulator in TO-220-3 with 1A output and \u00b14% tolerance. The ACT suffix offers \u00b12% precision. For surface-mount designs, use MC7812ABD2TG (DPAK). For battery-powered systems, the LM2940CT-1.2 LDO version reduces dropout to 0.5V. All 7812 variants are pin-compatible (IN-GND-OUT) and require only input\/output capacitors.<\/p>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7930","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=7930"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7930\/revisions"}],"predecessor-version":[{"id":8233,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7930\/revisions\/8233"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/media?parent=7930"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/categories?post=7930"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/tags?post=7930"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/chip_brand?post=7930"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}