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LM7805CT

1A fixed 5V positive regulator, 7-35V input, TO-220, thermal protection

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Manufacturer Part：

LM7805CT

Package：

TO-220 (10.67 x 9.04 x 4.57mm, 3-pin through-hole)

Brand：

Product Categories：

Integrated Circuits ICs, Low Dropout Regulators (LDO)

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Description

Product Overview

The LM7805CT is a 1A positive voltage regulator from onsemi/TI providing a fixed 5V output with 2V typical dropout, thermal overload protection, and short-circuit current limiting in a TO-220 package.

Key Specifications

Output Voltage	5V fixed (±2% at 25°C)
Output Current	1A (with adequate heatsinking)
Input Voltage Range	7V to 35V
Dropout Voltage	2V typical at 1A
Line Regulation	0.01%/V typical
Load Regulation	10mV typical (5mA to 1.5A)
Quiescent Current	4.2mA typical
Ripple Rejection	80dB typical at 120Hz
Output Noise	40µVrms typical
Thermal Shutdown	150°C typical
Short Circuit Current	750mA typical (current limited)
Operating Temperature	0°C to +125°C
Package	TO-220 (3-pin, through-hole)

Features

Fixed 5V output with ±2% tolerance at 25°C
1A output current with proper heatsinking
Internal thermal overload protection
Internal short-circuit current limiting
Output transistor safe area compensation
80dB ripple rejection at 120Hz
No external components required for basic operation
Industry-standard 7805 pinout

Applications

5V logic power supplies
Microcontroller and digital circuit power
Post-regulation for switching supplies
Bench and laboratory power supplies
Automotive and battery chargers

Product Introduction:LM7805CT Product Introduction

The LM7805CT is the industry-standard 5V positive voltage regulator, one of the most widely used linear regulators in electronics. It provides a fixed 5V output at up to 1A with only two external bypass capacitors required. The internal thermal shutdown at 150°C protects against overheating, while the short-circuit current limiting at 750mA typical prevents damage from output faults. The 80dB ripple rejection at 120Hz makes it effective for post-regulating rectified AC or switching converter outputs. The TO-220 package allows heatsinking for higher power dissipation. With over 40 years in production, the LM7805 remains the go-to solution for simple 5V power supplies.

Working Principle:LM7805CT Working Principle

The LM7805CT uses a series pass transistor (NPN Darlington) controlled by an error amplifier that compares a fraction of the output voltage with an internal bandgap reference. The error amplifier drives the base of the pass transistor to maintain the output at 5V. The series pass element dissipates power equal to (VIN – VOUT) × ILOAD as heat, requiring a heatsink for high differential voltages or load currents. The thermal shutdown circuit monitors the junction temperature and turns off the pass transistor when it exceeds approximately 150°C, preventing damage. The current-limiting circuit senses the output current through a small series resistor and reduces the drive to the pass transistor when the current exceeds approximately 750mA. Safe area protection reduces the current limit as the input-output voltage differential increases, keeping the pass transistor within its safe operating area (SOA). The 80dB ripple rejection is achieved by the high gain of the error amplifier, which suppresses input ripple at 120Hz by a factor of 10,000. The quiescent current of 4.2mA flows through the internal bias network and is delivered to the load rather than wasted.

Pin Description:LM7805CT Pin Definition and Functions

Pin	Name	Type	Description
1	INPUT	Power	Unregulated input voltage (7V-35V)
2	GND	Power	Ground (common, tab)
3	OUTPUT	Power	Regulated 5V output

Application Scenarios:In which products and applications isLM7805CT used

5V Logic Power: Fixed 5V output directly powers TTL, CMOS, and MCU circuits from 9V or 12V sources
Post-Regulation: 80dB ripple rejection cleans switching converter output for noise-sensitive analog circuits
Bench Supplies: TO-220 with heatsink provides reliable 5V at 1A for prototyping and test fixtures
Automotive: 7-35V input range tolerates automotive battery voltage for 5V accessory power
Educational: Simplest possible regulator circuit (2 capacitors + LM7805) teaches linear regulation fundamentals

Alternative Models:What chips are recommended as replacements for LM7805CT

Model	Manufacturer	Key Difference	Package	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.