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LM1085
3A Low Dropout Positive Regulators
General Description
The LM1085 is a series of low dropout positive voltage
regulators with a maximum dropout of 1.5V at 3A of load
current. It has the same pin-out as National Semiconductor’s
industry standard LM317.
The LM1085 is available in an adjustable version, which can
set the output voltage with only two external resistors. It is
also available in three fixed voltages: 3.3V, 5.0V and 12.0V.
The fixed versions integrate the adjust resistors.
The LM1085 circuit includes a zener trimmed bandgap ref-
erence, current limiting and thermal shutdown.
The LM1085 series is available in TO-220 and TO-263 pack-
ages. Refer to the LM1084 for the 5A version, and the
LM1086 for the 1.5A version.
Features
n Available in 3.3V, 5.0V, 12V and Adjustable Versions
n Current Limiting and Thermal Protection
n Output Current 3A
n Line Regulation 0.015% (typical)
n Load Regulation 0.1% (typical)
Applications
n High Efficiency Linear Regulators
n Battery Charger
n Post Regulation for Switching Supplies
n Constant Current Regulator
n Microprocessor Supply
Connection Diagrams
TO-220
10094702
Top View
TO-263
10094704
Top View
Basic Functional Diagram,
Adjustable Version
10094765
Application Circuit
10094752
1.2V to 15V Adjustable Regulator
June 2005
LM1085 3A Low Dropout Positive Regulators
© 2005 National Semiconductor Corporation DS100947 www.national.com