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LM7805CT

5V 1A positive linear regulator, TO-220, thermal/SCP protection

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Pieza del fabricante：

LM7805CT

Paquete：

TO-220-3 (15.6 x 10.6 x 4.6mm, through-hole, tab=GND)

Marca：

Categorías de productos：

Circuitos integrados IC, Microcontroladores y procesadores

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Descripción

Productos

The LM7805CT from onsemi/TI is a 3-terminal 1A positive voltage regulator providing a fixed 5V output with internal thermal shutdown and short-circuit protection in a TO-220 package — the most widely used 5V regulator in electronics.

Especificaciones

Output Voltage	5V fixed (±2% at 25°C for A-grade)
Corriente de salida	1A continuous (1.5A peak)
Input Voltage Range	7.5V to 20V (7.5V min for regulation)
Maximum Input Voltage	35V
Dropout Voltage	2V typical @ 1A
Line Regulation	5mV typical (7.5V to 20V)
Load Regulation	10mV typical (5mA to 1A)
Corriente de reposo	5mA typical
Ripple Rejection	68dB typical @ 120Hz
Thermal Shutdown	~170°C junction
Short-Circuit Current	2.1A typical
Temperatura de funcionamiento	-40°C to +125°C (junction)
Paquete	TO-220-3 (through-hole, tab=GND)

Características

Fixed 5V output — the standard logic supply voltage
1A continuous output current
Internal thermal overload protection
Internal short-circuit current limiting
Output transistor safe operating area protection
68dB ripple rejection at 120Hz
Only two external capacitors needed

Aplicaciones

5V logic power supply
Microcontroller voltage regulation
Post-regulator after switching supply
Bench power supply
USB 5V power source

Introducción del producto:LM7805CT Presentación del producto

The LM7805CT from onsemi/Texas Instruments is the most ubiquitous voltage regulator in electronics, providing a fixed 5V output at up to 1A from an input of 7.5V or higher. It is the backbone of virtually every 5V logic power supply, from Arduino boards to industrial controllers. The device requires only two external capacitors (0.33µF input, 0.1µF output) for stable operation. The 2V dropout voltage means the input must be at least 7V to maintain 5V output at full load. The 68dB ripple rejection effectively attenuates AC mains ripple by a factor of 2500, making the output clean enough for sensitive analog circuits. Internal protection includes thermal shutdown (disables output at ~170°C junction), current limiting (short-circuit current limited to ~2.1A), and safe operating area compensation. The CT suffix denotes the TO-220 package. For lower dropout alternatives, the LM2940 (0.5V dropout at 1A) is preferred when input voltage is close to 5V.

Principio de funcionamiento:LM7805CT Principio de funcionamiento

The LM7805CT 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. When the output voltage drops below 5V, the error amplifier increases the drive to the pass transistor, increasing current flow. When the output rises above 5V, the drive is reduced. The thermal protection circuit monitors the junction temperature; at ~170°C, the pass transistor is disabled until the device cools. The current limiting circuit limits the pass transistor current to approximately 2.1A during a short circuit. The safe operating area (SOA) protection further reduces the current limit as the input-output voltage differential increases. The 5mA quiescent current flows through the ground pin and biases the internal reference and error amplifier. The 0.33µF input capacitor prevents oscillation when the source impedance is high, and the 0.1µF output capacitor improves transient response.

Descripción de la clavija:LM7805CT Definición y funciones de las clavijas

Pin	Nombre	Tipo	Descripción
1	INPUT	Entrada de alimentación	Unregulated input voltage. Must be at least 3.0V (Vout + Vdropout ≈ 3.0V) 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 0.5V 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 0.5V 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 isLM7805CT usado

5V MCU Supply: 9V battery or wall adapter → LM7805CT → 5V for MCU, TTL logic, sensors; 0.33µF + 0.1µF caps
Arduino Power: 12V DC jack → LM7805CT → 5V rail; Pdiss = (12-5)×0.5A = 3.5W; small heatsink needed
Post-SMPS: 7.5V switching supply → LM7805CT → clean 5V; 68dB ripple rejection eliminates switcher noise
USB Power: 9V battery → LM7805CT → 5V USB output; charges phone or powers USB device
Split Supply: LM7805CT (+5V) + LM7905CT (-5V) from center-tapped transformer; ±5V for op-amp circuits

Alternative Models:What chips are recommended as replacements for LM7805CT

Modelo	Fabricante	Diferencia clave	Paquete	Specs
LM7805ACT	onsemi	Tighter output tolerance: ±2% vs ±4% for precision power supply applications	TO-220-3	0.5V/1A
L7805CV	STMicroelectronics	Direct equivalent with 1.5A output current, internal thermal shutdown and current limiting	TO-220-3	0.5V/1.5A
MC7805CTG	onsemi	Current production replacement with identical electrical specifications and RoHS compliance	TO-220-3	0.5V/1A
KA7805	onsemi/Fairchild	Budget-friendly version with ±4% tolerance and standard 1A output current rating	TO-220-3	0.5V/1A
MC7805ABD2TG	onsemi	Surface-mount DPAK version with ±2% A-grade tolerance for compact PCB layouts	DPAK-3	0.5V/1A
LM2940CT-0.5	TI	Low-dropout version with 0.5V max dropout at 1A for battery-powered and automotive systems	TO-220-3	0.5V/1A LDO

LM7805CT is a 0.5V 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 MC7805ABD2TG (DPAK). For battery-powered systems, the LM2940CT-0.5 LDO version reduces dropout to 0.5V. All 7805 variants are pin-compatible (IN-GND-OUT) and require only input/output capacitors.