LINEAR TECHNOLOGY LT1579 User Guide
Summary
This advanced low-dropout regulator provides reliable 300mA output power with automatic switching between two independent input sources. Featuring critical protection methods, like reverse-battery, current limiting, and status monitoring flags, it guarantees uninterrupted operation for critical systems requiring backup power (e.g., embedded or industrial electronics). This technical guide details the device's operational characteristics, adjustable voltage options, and advanced failure management features, making it essential reading for power system architects and hardware engineers.
Page 1 Text Content
LT1579
INPUT CURRENT (m A)
300m A Dual Input Smart Battery Backup Regulator
FEATURES DESCRIPTION
Maintains Output Regulation with Dual Inputs The LT®1579 is a dual input, single output, low dropout Dropout Voltage: 0.4V regulator. This device is designed to provide an Output Current: 300m A uninterruptible output voltage from two independent input 50µA Quiescent Current voltage sources on a priority basis. All of the circuitry
No Protection Diodes Needed needed to switch smoothly and automatically between Two Low-Battery Comparators inputs is incorporated.
Status Flags Aid Power Management
The LT1579 can supply 300m A of output current from
Adjustable Output from 1.5V to 20V
either input at a dropout voltage of 0.4V. Quiescent current
Fixed Output Voltages: 3V, 3.3V and 5V
is 50µA, dropping to 7µA in shutdown. Two comparators
7µA Quiescent Current in Shutdown
are included to monitor input voltage status. Two addi-
Reverse-Battery Protection
tional status flags indicate which input is supplying power
Reverse Current Protection
and provide an early warning against loss of output
Remove, Recharge and Replace Batteries Without
regulation when both inputs are low. A secondary select
Loss of Regulation OU TP UT OL TA GE (V Daisy-Chained Control Outputs IN PU VO LT AG (V
pin is provided so that the user can force the device to switch from the primary input to the secondary input. APPLICATIONS Internal protection circuitry includes reverse-battery pro- tection, current limiting, thermal limiting and reverse-
Dual Battery Systems
current protection.
Battery Backup Systems
The device is available in fixed output voltages of 3V, 3.3V
Automatic Power Management for
and 5V, and as an adjustable device with a 1.5V reference
Battery-Operated Systems
voltage. The LT1579 regulators are available in narrow
, LTC and LT are registered trademarks of Linear Technology Corporation.
16-lead SO and 16-lead SSOP packages with all features, and in SO-8 with limited features.
TYPICAL APPLICATION
5V Dual Battery Supply Automatic Input Switching
IN1 OUT VIN2 = 10V
300m A VIN1
ILOAD = 50m ASWITCHOVER
1µF 4.7µF POINT
IIN1 IIN2
1M LT1579-5
SS IN2 SHDN
2.7M LBO1
1µF POWER
LBI2 LB02 5.05
MANAGEMENT
1M BACKUP 5.00 DROPOUT
BIASCOMP GND 0.01µF
TIME (ms)
1579 TA01
1578 TA02
Page Summary Contents For LINEAR TECHNOLOGY LT1579 User Guide
Manual Details
| Brand | Linear |
|---|---|
| Pages | 20 |
| File Size | 294.70 KB |
| Published | June 03, 2026 |
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Frequently Asked Questions
What is the maximum output current?
The device can supply 300mA of uninterruptible output voltage.
How does the LT1579 switch between input sources?
It automatically monitors two independent inputs and provides status flags indicating which input is supplying power. You can also manually force a switch using the Loss of Regulation pin.
What kind of protection features are included?
Internal circuitry includes reverse-battery protection, current limiting, thermal limiting, and dual battery systems current protection.
Can I operate this with multiple voltages?
Yes. It is available as an adjustable device (1.5V to 20V) or fixed in 3V, 3.3V, and 5V options.