Home > Integrated Circuits ICs > LM7808CT

LM7808CT

8V 1A positive linear regulator, TO-220, thermal/SCP protection

5000

Effective Inventory

Go to Inquiry

Image for reference only

Manufacturer Part：

LM7808CT

Package：

TO-220-3 (15.75 x 10.16 x 4.7mm, through-hole, tab=GND)

Brand：

Product Categories：

Integrated Circuits ICs, Microcontrollers & Processors

Other recommendations you may be interested in.

SII9396SCNUC-BAR

IS43TR16256BL-125KBLI

Description

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 (±4% at 25°C)
Output Current	1A continuous
Input Voltage Range	10.5V to 35V
Dropout Voltage	2V typical @ 1A
Line Regulation	5mV typical (10.5V to 25V)
Load Regulation	10mV typical (5mA to 1.5A)
Quiescent Current	5mA typical
Ripple Rejection	73dB typical @ 120Hz
Output Noise	52µV/VO (10Hz to 100kHz)
Thermal Shutdown	~170°C junction
Operating Temperature	-40°C to +125°C (junction)
Package	TO-220-3 (through-hole, tab=GND)

Features

Fixed 8V output
1A continuous output current
Internal thermal overload protection
Internal short-circuit current limiting
73dB ripple rejection
Only two external capacitors needed

Applications

8V logic and analog supply
Op-amp power supply
Post-regulator
Instrumentation power

Product Introduction:LM7808CT 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 (0.33µF input, 0.1µF 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°C to +125°C).

Working Principle:LM7808CT 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°C 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 − VOUT) × IOUT; at VIN=18V and IOUT=500mA, Pd = (18-8)×0.5 = 5W, requiring a heatsink with θSA < (TJ_max − TA)/Pd − θJC − θCS = (125−50)/5 − 5 − 0.5 = 9.5°C/W.

Pin Description:LM7808CT Pin Definition and Functions

Pin	Name	Description
1	INPUT	Unregulated DC input (10.5 V to 35 V); connect 0.33 uF capacitor to GND if more than 4 inches from rectifier filter
2	GND	Common ground; connect to heatsink tab for TO-220 thermal dissipation
3	OUTPUT	Regulated 8 V output; connect 0.1 uF capacitor to GND for improved transient response and stability

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.

Application Scenarios:In which products and applications isLM7808CT used

8 V Analog Supply Rails: 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
Split-Supply Audio Systems: Pairing LM7808CT (+8 V) with LM7908CT (-8 V) on a center-tapped transformer secondary for balanced +/-8 V audio op-amp rails
Post-SMPS Linear Regulation: Cascading after a switching pre-regulator to clean up 12 V switcher ripple for sensitive analog circuitry with 60 dB ripple rejection
Relay and Solenoid Drivers: Providing a stable 8 V supply for 8 V DC relay coils and solenoid actuators from automotive or industrial 12 V bus
Instrumentation Reference Supply: Powering strain gauge bridges and transducer excitation circuits requiring a stable 8 V reference with 0.1% line regulation

Alternative Models:What chips are recommended as replacements for LM7808CT

Model	Manufacturer	Key Difference	Package	Voltage
LM7808ACT	onsemi	Tighter output tolerance: ±2% vs ±4% for higher precision applications	TO-220-3	8V fixed
L7808CV	STMicroelectronics	Direct equivalent with 1.5A output current and internal thermal shutdown protection	TO-220-3	8V fixed
KA7808	onsemi/Fairchild	Budget-friendly version with ±4% tolerance and standard 1A output rating	TO-220-3	8V fixed
MC7808CTG	onsemi	Current production replacement with identical specifications and RoHS compliance	TO-220-3	8V fixed
MC7808ACD2TG	onsemi	Surface-mount DPAK version for compact PCB layouts, ±2% tolerance A-grade	DPAK-3	8V fixed
LM340AT-8	TI	TI equivalent with ±2% tolerance and 1A output, wide input range up to 35V	TO-220-3	8V fixed

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.