{"id":7956,"date":"2026-06-28T06:10:19","date_gmt":"2026-06-28T06:10:19","guid":{"rendered":"https:\/\/materialparts.com\/lm7808ct-2\/"},"modified":"2026-06-28T11:45:21","modified_gmt":"2026-06-28T11:45:21","slug":"lm7808ct-2","status":"publish","type":"post","link":"https:\/\/materialparts.com\/zh\/lm7808ct-2\/","title":{"rendered":"LM7808CT"},"content":{"rendered":"

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

The LM7808CT from onsemi is a 3-terminal 1A positive voltage regulator providing a fixed 8V output with internal thermal shutdown and short-circuit protection 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
Output Voltage<\/td>\n8V 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>\n10.5V to 35V<\/td>\n<\/tr>\n
Dropout Voltage<\/td>\n2V typical @ 1A<\/td>\n<\/tr>\n
Line Regulation<\/td>\n5mV typical (10.5V to 25V)<\/td>\n<\/tr>\n
Load Regulation<\/td>\n10mV typical (5mA to 1.5A)<\/td>\n<\/tr>\n
\u9759\u6001\u7535\u6d41<\/td>\n5mA typical<\/td>\n<\/tr>\n
Ripple Rejection<\/td>\n73dB typical @ 120Hz<\/td>\n<\/tr>\n
Output Noise<\/td>\n52\u00b5V\/VO (10Hz to 100kHz)<\/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 8V output<\/li>\n
  • 1A continuous output current<\/li>\n
  • Internal thermal overload protection<\/li>\n
  • Internal short-circuit current limiting<\/li>\n
  • 73dB ripple rejection<\/li>\n
  • Only two external capacitors needed<\/li>\n<\/ul>\n

    \u5e94\u7528<\/h2>\n
      \n
    • 8V logic and analog supply<\/li>\n
    • Op-amp power supply<\/li>\n
    • Post-regulator<\/li>\n
    • Instrumentation power<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"

      Product Overview The LM7808CT from onsemi is a 3-terminal 1A positive voltage regulator providing a fixed 8V output with internal thermal shutdown and short-circuit protection in a TO-220 package. Key Specifications Output Voltage 8V fixed (\u00b14% at 25\u00b0C) Output Current 1A continuous Input Voltage Range 10.5V to 35V Dropout Voltage 2V typical @ 1A Line […]<\/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-7956","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-microcontrollers-processors","chip_brand-ti"],"acf":{"brief_explanation":"8V 1A positive linear regulator, TO-220, thermal\/SCP protection","date_code":"","package_case":"TO-220-3 (15.75 x 10.16 x 4.7mm, through-hole, tab=GND)","in_stock":5000,"datasheet":"https:\/\/www.onsemi.com\/pub\/Collateral\/LM78XX-D.PDF","price":"$0.48 @ 1ku","product_introduction":"The LM7808CT from onsemi is a member of the LM78XX series of 3-terminal positive voltage regulators, providing a fixed 8V output at up to 1A. The 8V output is useful for powering analog circuits, op-amps, and some older logic families that require 8V rails. The device requires only two external capacitors (0.33\u00b5F input, 0.1\u00b5F output) for stable operation. The 2V dropout voltage means the input must be at least 10V to maintain regulation. The 73dB ripple rejection effectively attenuates AC mains ripple by a factor of ~4500, making the output clean for sensitive analog circuits. The CT suffix denotes the TO-220 package with commercial\/industrial temperature range (-40\u00b0C to +125\u00b0C).","working_principle":"The LM7808CT uses a series pass transistor controlled by a feedback loop comparing a fraction of the output voltage with an internal bandgap reference. When the output drops below 8V, the error amplifier increases drive to the pass transistor. When the output rises above 8V, the drive is reduced. The thermal protection disables the pass transistor at ~170\u00b0C junction. The current limiting restricts output current during a short circuit. The minimum input voltage for regulation is VOUT + Vdropout = 8V + 2V = 10V. The maximum input voltage is 35V. Power dissipation is Pd = (VIN \u2212 VOUT) \u00d7 IOUT; at VIN=18V and IOUT=500mA, Pd = (18-8)\u00d70.5 = 5W, requiring a heatsink with \u03b8SA < (TJ_max \u2212 TA)\/Pd \u2212 \u03b8JC \u2212 \u03b8CS = (125\u221250)\/5 \u2212 5 \u2212 0.5 = 9.5\u00b0C\/W.","pin_description":"
      Pin<\/th>Name<\/th>Description<\/th><\/tr>
      1<\/td>INPUT<\/td>Unregulated DC input (10.5 V to 35 V); connect 0.33 uF capacitor to GND if more than 4 inches from rectifier filter<\/td><\/tr>
      2<\/td>GND<\/td>Common ground; connect to heatsink tab for TO-220 thermal dissipation<\/td><\/tr>
      3<\/td>OUTPUT<\/td>Regulated 8 V output; connect 0.1 uF capacitor to GND for improved transient response and stability<\/td><\/tr><\/table>

      Package: TO-220-3 (vertical mount). Thermal resistance Rth(j-a) = 50 C\/W (no heatsink), Rth(j-c) = 5 C\/W. Maximum power dissipation 2 W without heatsink at 25 C ambient.<\/p>","application_scenarios":"

      • 8 V Analog Supply Rails:<\/strong> Deriving a clean 8 V rail from 12 V or 15 V unregulated DC for op-amp power supplies; 0.33 uF input and 0.1 uF output bypass capacitors ensure stability<\/li>
      • Split-Supply Audio Systems:<\/strong> Pairing LM7808CT (+8 V) with LM7908CT (-8 V) on a center-tapped transformer secondary for balanced +\/-8 V audio op-amp rails<\/li>
      • Post-SMPS Linear Regulation:<\/strong> Cascading after a switching pre-regulator to clean up 12 V switcher ripple for sensitive analog circuitry with 60 dB ripple rejection<\/li>
      • Relay and Solenoid Drivers:<\/strong> Providing a stable 8 V supply for 8 V DC relay coils and solenoid actuators from automotive or industrial 12 V bus<\/li>
      • Instrumentation Reference Supply:<\/strong> Powering strain gauge bridges and transducer excitation circuits requiring a stable 8 V reference with 0.1% line regulation<\/li><\/ul>","alternative_models":"\n
        Model<\/th>Manufacturer<\/th>Key Difference<\/th>Package<\/th>Voltage<\/th><\/tr>\n
        LM7808ACT<\/td>onsemi<\/td>Tighter output tolerance: \u00b12% vs \u00b14% for higher precision applications<\/td>TO-220-3<\/td>8V fixed<\/td><\/tr>\n
        L7808CV<\/td>STMicroelectronics<\/td>Direct equivalent with 1.5A output current and internal thermal shutdown protection<\/td>TO-220-3<\/td>8V fixed<\/td><\/tr>\n
        KA7808<\/td>onsemi\/Fairchild<\/td>Budget-friendly version with \u00b14% tolerance and standard 1A output rating<\/td>TO-220-3<\/td>8V fixed<\/td><\/tr>\n
        MC7808CTG<\/td>onsemi<\/td>Current production replacement with identical specifications and RoHS compliance<\/td>TO-220-3<\/td>8V fixed<\/td><\/tr>\n
        MC7808ACD2TG<\/td>onsemi<\/td>Surface-mount DPAK version for compact PCB layouts, \u00b12% tolerance A-grade<\/td>DPAK-3<\/td>8V fixed<\/td><\/tr>\n
        LM340AT-8<\/td>TI<\/td>TI equivalent with \u00b12% tolerance and 1A output, wide input range up to 35V<\/td>TO-220-3<\/td>8V fixed<\/td><\/tr>\n<\/table>\n

        For new designs requiring surface-mount, consider MC7808ACD2TG (DPAK) or LM340AT-8 (TI). All 78xx 8V regulators are pin-compatible with standard TO-220-3 footprint (IN-GND-OUT). Input voltage must exceed 10.5V for proper regulation.<\/p>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7956","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=7956"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7956\/revisions"}],"predecessor-version":[{"id":8116,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/7956\/revisions\/8116"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/media?parent=7956"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/categories?post=7956"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/tags?post=7956"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/chip_brand?post=7956"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}