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LM7812CT

12V 1A positive linear regulator, TO-220, thermal/SCP protection

25000

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Pieza del fabricante：

LM7812CT

Paquete：

TO-220-3 (10.16 x 4.7 x 20.4mm, through-hole, tab=GND)

Marca：

Categorías de productos：

Circuitos integrados IC, Microcontroladores y procesadores

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Descripción

Productos

The LM7812CT from onsemi is a 3-terminal 1A positive voltage regulator providing a fixed 12V output with 71dB ripple rejection and internal protection in a TO-220 package — the standard 12V regulator for industrial and automotive electronics.

Especificaciones

Output Voltage	12V fixed (±4% at 25°C)
Corriente de salida	1A continuous
Input Voltage Range	14.5V to 35V
Dropout Voltage	2V typical @ 1A
Line Regulation	10mV typical (14.5V to 27V)
Load Regulation	12mV typical (5mA to 1.5A)
Corriente de reposo	5.1mA typical
Ripple Rejection	71dB typical @ 120Hz
Output Noise	76µV/VO (10Hz to 100kHz)
Short-Circuit Current	250mA typical
Temperatura de funcionamiento	-40°C to +125°C (junction)
Paquete	TO-220-3 (through-hole, tab=GND)

Características

Fixed 12V output — the most common industrial supply voltage
1A continuous output current
Internal thermal overload protection
Internal short-circuit current limiting
71dB ripple rejection
Output transistor SOA protection

Aplicaciones

12V industrial power supply
Automotive 12V rail
Relay and solenoid power
Op-amp ±12V supply
Instrumentation power

Introducción del producto:LM7812CT Presentación del producto

The LM7812CT from onsemi is the 12V member of the LM78XX family — arguably the most important voltage in the series because 12V is the dominant supply rail in industrial, automotive, and communications equipment. From 12V, 5V can be derived with a secondary regulator (LM7805), and ±12V supplies are used for analog op-amp circuits. The minimum input voltage for regulation is 14.5V (12V + 2.5V dropout margin), making it ideal for automotive applications where the 14.4V alternator output directly feeds the regulator. The 71dB ripple rejection attenuates alternator whine and rectified AC ripple. The CT suffix denotes the TO-220 package. Power dissipation can be significant: at VIN=24V and IOUT=500mA, Pd = (24-12)×0.5 = 6W, requiring a heatsink.

Principio de funcionamiento:LM7812CT Principio de funcionamiento

The LM7812CT uses a series pass transistor (NPN Darlington) between input and output, controlled by a feedback loop that compares a fraction of the output voltage with an internal bandgap reference. When the output drops below 12V, the error amplifier increases drive to the pass transistor, increasing current flow. When the output rises above 12V, drive is reduced. The thermal protection disables the output at ~170°C junction temperature. The current limiting restricts output during a short circuit to ~250mA. The safe operating area (SOA) protection further reduces current limit as the input-output differential increases. The 5.1mA quiescent current flows through the ground pin and biases the internal reference and error amplifier. Power dissipation is Pd = (VIN − 12V) × IOUT; at VIN=18V, IOUT=1A: Pd = 6W. The heatsink thermal resistance must satisfy: θSA < (TJ_max − TA)/Pd − θJC − θCS. For TJ=100°C, TA=50°C: θSA < 50/6 − 5 − 0.5 = 2.83°C/W — a substantial heatsink.

Descripción de la clavija:LM7812CT Definición y funciones de las clavijas

Pin	Nombre	Tipo	Descripción
1	INPUT	Entrada de alimentación	Unregulated input voltage. Must be at least 3.7V (Vout + Vdropout ≈ 3.7V) for proper regulation. Maximum 35V. Bypass with 0.33µF ceramic capacitor to GND if supply is more than 6 inches from the regulator.
2	GND	Suelo	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.
3	OUTPUT	Potencia de salida	Regulated 1.2V DC output at up to 1A continuous current with ±4% tolerance. Bypass with 0.1µF 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.

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 0.1µF is required for stability; input capacitance of 0.33µF is recommended when the input supply is remote.

Application Scenarios:In which products and applications isLM7812CT usado

12V Industrial Supply: 18V DC (from transformer+rectifier+filter) → LM7812CT → 12V rail; 0.33µF input + 0.1µF output caps
Dual 12V/5V: 18V → LM7812CT → 12V rail; 12V → LM7805CT → 5V rail; cascaded regulation
±12V Op-Amp Supply: LM7812CT (+12V) + LM7912CT (-12V) from center-tapped transformer; clean ±12V for NE5532
Automotive 12V: Car 14.4V → LM7812CT → stable 12V; 71dB rejection of alternator noise

Alternative Models:What chips are recommended as replacements for LM7812CT

Modelo	Fabricante	Diferencia clave	Paquete	Specs
LM7812ACT	onsemi	Tighter output tolerance: ±2% vs ±4% for precision power supply applications	TO-220-3	1.2V/1A
L7812CV	STMicroelectronics	Direct equivalent with 1.5A output current, internal thermal shutdown and current limiting	TO-220-3	1.2V/1.5A
MC7812CTG	onsemi	Current production replacement with identical electrical specifications and RoHS compliance	TO-220-3	1.2V/1A
KA7812	onsemi/Fairchild	Budget-friendly version with ±4% tolerance and standard 1A output current rating	TO-220-3	1.2V/1A
MC7812ABD2TG	onsemi	Surface-mount DPAK version with ±2% A-grade tolerance for compact PCB layouts	DPAK-3	1.2V/1A
LM2940CT-1.2	TI	Low-dropout version with 0.5V max dropout at 1A for battery-powered and automotive systems	TO-220-3	1.2V/1A LDO

LM7812CT is a 1.2V fixed positive voltage regulator in TO-220-3 with 1A output and ±4% tolerance. The ACT suffix offers ±2% 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.