LM3940 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 1A Low Dropout Regulator for 5V to 3.3V Conversion

LM3940
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SNVS114E – MAY 1999 – REVISED MARCH 2013
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion
Check for Samples: LM3940
FEATURES
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•2 Output voltage specified over temperature
• Excellent load regulation
• Specified 1A output current
• Requires only one external component
• Built-in protection against excess temperature
• Short circuit protected
APPLICATIONS
• Laptop/Desktop Computers
• Logic Systems
DESCRIPTION
The LM3940 is a 1A low dropout regulator designed to provide 3.3V from a 5V supply.
The LM3940 is ideally suited for systems which contain both 5V and 3.3V logic, with prime power provided from
a 5V bus.
Because the LM3940 is a true low dropout regulator, it can hold its 3.3V output in regulation with input voltages
as low as 4.5V.
The TO-220 package of the LM3940 means that in most applications the full 1A of load current can be delivered
without using an additional heatsink.
The surface mount DDPAK/TO-263 package uses minimum board space, and gives excellent power dissipation
capability when soldered to a copper plane on the PC board.
TYPICAL APPLICATION
*Required if regulator is located more than 1″ from the power supply filter capacitor or if battery power is used.
**See APPLICATION HINTS.
CONNECTION DIAGRAM
Figure 1. 3-Lead TO-220 Package
(Front View)
Drawing Number NDE00EB
Figure 2. 3-Lead DDPAK/TO-263 Package
(Front View)
Drawing Number KTT003B
Figure 3. 3-Lead SOT-223
(Front View)
Drawing Number DCY (R-PDSO-G4)
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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