{"id":7971,"date":"2026-06-28T06:17:40","date_gmt":"2026-06-28T06:17:40","guid":{"rendered":"https:\/\/materialparts.com\/lm7912ct-2\/"},"modified":"2026-06-28T11:45:00","modified_gmt":"2026-06-28T11:45:00","slug":"lm7912ct-2","status":"publish","type":"post","link":"https:\/\/materialparts.com\/zh\/lm7912ct-2\/","title":{"rendered":"LM7912CT"},"content":{"rendered":"

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

The LM7912CT from onsemi is a 3-terminal 1A negative voltage regulator providing a fixed -12V output with internal thermal shutdown and short-circuit protection in a TO-220 package \u2014 the negative complement to the LM7812CT for split-rail supplies.<\/p>\n

\u4e3b\u8981\u89c4\u683c<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n
Output Voltage<\/td>\n-12V fixed (\u00b14% at 25\u00b0C)<\/td>\n<\/tr>\n
\u8f93\u51fa\u7535\u6d41<\/td>\n1A continuous<\/td>\n<\/tr>\n
\u8f93\u5165\u7535\u538b\u8303\u56f4<\/td>\n-14.5V to -35V<\/td>\n<\/tr>\n
Dropout Voltage<\/td>\n2V typical @ 1A<\/td>\n<\/tr>\n
Line Regulation<\/td>\n10mV typical<\/td>\n<\/tr>\n
Load Regulation<\/td>\n15mV typical<\/td>\n<\/tr>\n
\u9759\u6001\u7535\u6d41<\/td>\n3mA typical<\/td>\n<\/tr>\n
Ripple Rejection<\/td>\n60dB typical @ 120Hz<\/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<\/li>\n
  • 1A continuous output current<\/li>\n
  • Internal thermal overload protection<\/li>\n
  • Internal short-circuit current limiting<\/li>\n
  • 60dB ripple rejection<\/li>\n
  • Complement to LM7812CT (+12V)<\/li>\n<\/ul>\n

    \u5e94\u7528<\/h2>\n
      \n
    • \u00b112V split power supply<\/li>\n
    • Op-amp negative rail<\/li>\n
    • RS-232 negative supply<\/li>\n
    • Audio amplifier \u00b112V<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM7912CT from onsemi is a 3-terminal 1A negative voltage regulator providing a fixed -12V output with internal thermal shutdown and short-circuit protection in a TO-220 package \u2014 the negative complement to the LM7812CT for split-rail supplies. Key Specifications Output Voltage -12V fixed (\u00b14% at 25\u00b0C) Output Current 1A continuous Input Voltage Range […]<\/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-7971","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-microcontrollers-processors","chip_brand-ti"],"acf":{"brief_explanation":"-12V 1A negative linear regulator, TO-220, thermal\/SCP protection","date_code":"","package_case":"TO-220-3 (10.16 x 4.7 x 20.4mm, through-hole, tab=GND)","in_stock":8000,"datasheet":"https:\/\/www.onsemi.com\/pub\/Collateral\/LM79XX-D.PDF","price":"$0.50 @ 1ku","product_introduction":"The LM7912CT from onsemi is the negative-voltage counterpart of the LM7812CT, providing a fixed -12V output at up to 1A. Together, the LM7812 (+12V) and LM7912 (-12V) form a complete \u00b112V split power supply, which is the standard supply voltage for operational amplifiers (NE5532, TL072, LM741), analog switches, and many other linear ICs. The negative regulator operates with a negative input voltage: the input must be more negative than -14.5V (at least 2.5V below -12V) to maintain regulation. The pinout differs from the 78XX: pin 1 is GND (not input), pin 2 is input (not GND), pin 3 is output. This pinout difference is critical \u2014 inserting a 7912 in a 7812 socket will damage the device. The tab is connected to GND (same as 7812), so both can share a common heatsink without electrical isolation. The CT suffix denotes the TO-220 package.","working_principle":"The LM7912CT operates identically to the LM7812CT but with all voltages negated. It uses a series pass transistor between the negative input and the -12V output, controlled by a feedback loop comparing the output voltage with an internal reference. When the output rises above -12V (toward 0V), the pass transistor is driven harder to pull the output more negative. When the output drops below -12V, the drive is reduced. The thermal protection disables the output when the junction temperature exceeds ~175\u00b0C. The current limiting restricts output during a short circuit. The 60dB ripple rejection attenuates input ripple by a factor of ~1000. Power dissipation: Pd = |VIN \u2212 VOUT| \u00d7 IOUT = |-18V \u2212 (-12V)| \u00d7 1A = 6W, requiring a heatsink similar to the LM7812. Important: both input and output capacitors are required for stability \u2014 a 2.2\u00b5F tantalum at the input and 1\u00b5F at the output are recommended, placed close to the regulator.","pin_description":"\n
      Pin<\/th>Name<\/th>Type<\/th>Description<\/th><\/tr>\n
      1<\/td>GND<\/td>Ground<\/td>Common ground reference. The TO-220 tab is electrically connected to this pin. Note: 79xx negative regulators have GROUND on Pin 1 (opposite to 78xx where Input is Pin 1). Heatsink tab must be insulated when not at ground potential.<\/td><\/tr>\n
      2<\/td>INPUT<\/td>Power Input<\/td>Negative unregulated input voltage. Must be more negative than -1.2V - Vdropout (at least -3.2V input). Maximum -35V. Bypass with 2.2\u00b5F electrolytic or 0.33\u00b5F ceramic capacitor to GND.<\/td><\/tr>\n
      3<\/td>OUTPUT<\/td>Power Output<\/td>Regulated -1.2V DC output at up to 1.5A continuous current with \u00b14% tolerance. Bypass with 1\u00b5F tantalum or 10\u00b5F electrolytic capacitor to GND for stability. Do not apply positive voltage to output to prevent damage.<\/td><\/tr>\n<\/table>\n

      Critical note: 79xx negative regulators have DIFFERENT pin assignments from 78xx positive regulators. Pin 1 = GND (not Input), Pin 2 = Input (not GND), Pin 3 = Output. This pin swap is a common source of design errors. The tab is connected to GND (Pin 1). Always verify pinout against the datasheet before PCB layout.<\/p>","application_scenarios":"

        \n
      • \u00b112V Op-Amp Supply:<\/strong> Transformer center-tap \u2192 GND; positive winding \u2192 bridge+filter \u2192 LM7812CT (+12V); negative winding \u2192 bridge+filter \u2192 LM7912CT (-12V); clean \u00b112V for NE5532, TL072, LM741<\/li>\n
      • RS-232 Supply:<\/strong> LM7912CT provides -12V for MAX232 charge pump; combined with LM7812CT +12V<\/li>\n
      • Audio Amplifier:<\/strong> \u00b112V rails from LM7812+LM7912; Class-AB push-pull output stage; symmetrical clipping<\/li>\n<\/ul>","alternative_models":"\n
        Model<\/th>Manufacturer<\/th>Key Difference<\/th>Package<\/th>Specs<\/th><\/tr>\n
        LM7912ACT<\/td>onsemi<\/td>Tighter output tolerance: \u00b12% vs \u00b14% for precision negative supply rails<\/td>TO-220-3<\/td>-1.2V\/1A<\/td><\/tr>\n
        L7912CV<\/td>STMicroelectronics<\/td>Direct equivalent with 1.5A output current and internal thermal\/current protection<\/td>TO-220-3<\/td>-1.2V\/1.5A<\/td><\/tr>\n
        MC7912CTG<\/td>onsemi<\/td>Current production replacement with RoHS compliance and identical specifications<\/td>TO-220-3<\/td>-1.2V\/1A<\/td><\/tr>\n
        KA7912<\/td>onsemi\/Fairchild<\/td>Budget-friendly version with \u00b14% tolerance for cost-sensitive negative supply designs<\/td>TO-220-3<\/td>-1.2V\/1A<\/td><\/tr>\n
        LM337T<\/td>TI<\/td>Adjustable -1.25V to -37V version providing flexible output voltage with two external resistors<\/td>TO-220-3<\/td>-1.25 to -37V adj<\/td><\/tr>\n<\/table>\n

        LM7912CT is a -1.2V fixed negative voltage regulator in TO-220-3 with 1A output and \u00b14% tolerance. For adjustable negative voltage, the LM337T provides -1.25V to -37V output. All 7912 variants share the same pinout (GND-IN-OUT) and are complementary to the 7812 positive regulators for split-rail supplies.<\/p>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7971","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=7971"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7971\/revisions"}],"predecessor-version":[{"id":8216,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7971\/revisions\/8216"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/media?parent=7971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/categories?post=7971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/tags?post=7971"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/chip_brand?post=7971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}