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Details, datasheet, quote on part number:LM3940WG-3.3-QML
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Datasheet text preview:
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion
May 1999
LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion
General 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 T0-220 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 TO-263 package uses minimum board space, and gives excellent power dissipation capability when soldered to a copper plane on the PC board.
Features
n n n n n n Output voltage specified over temperature Excellent load regulation Guaranteed 1A output current Requires only one external component Built-in protection against excess temperature Short circuit protected
Applications
n Laptop/Desktop Computers n Logic Systems
Typical Application
DS012080-1
*Required if regulator is located more than 1" from the power supply filter capacitor or if battery power is used. **See Application Hints.
© 1999 National Semiconductor Corporation
DS012080
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Connection Diagram/Ordering Information
DS012080-2
DS012080-3
3-Lead TO-220 Package (Front View) Order Part Number LM3940IT-3.3 NSC Drawing Number TO3B
3-Lead TO-263 Package (Front View) Order Part Number LM3940IS-3.3 NSC Drawing Number TS3B
DS012080-10
3-Lead SOT-223 (Front View) Order Part Number LM3940IMP-3.3 Package Marked L52B NSC Drawing Number MA04A
DS012080-27 DS012080-28
16-Lead Ceramic Dual-in-Line Package (Top View) Order Part Number LM3940J-3.3-QML 5962-9688401QEA NSC Drawing Number J16A
16-Lead Ceramic Surface-Mount Package (Top View) Order Part Number LM3940WG-3.3-QML 5962-9688401QXA NSC Drawing Number WG16A
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range -65°C to +150°C
Operating Junction Temperature Range -40°C to +125°C Lead Temperature (Soldering, 5 seconds) 260°C Power Dissipation (Note 2) Internally Limited Input Supply Voltage 7.5V ESD Rating (Note 3) 2 kV
Electrical Characteristics
Limits in standard typeface are for TJ = 25°C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = 5V, IL = 1A, COUT = 33 µF. Symbol VO Parameter Output Voltage Line Regulation Conditions 5 mA IL 1A IL = 5 mA 4.5V VO 5.5V Load Regulation 50 mA IL 1A IL (DC) = 100 mA IL (AC) = 20 mA (rms) f = 120 Hz 4.5V VIN 5.5V IL = 5 mA VIN = 5V IL = 1A BW = 10 Hz 100 kHz IL = 5 mA IL = 1A IL = 100 mA IL(SC) Short Circuit Current RL = 0 35 50 80 ZO Output Impedance 35 10 110 150 0.5 110 1.7 1.2 0.8 1.0 150 200 A mV 15 20 200 250 µV (rms) V m mA Typical 3.3 20 LM3940 (Note 4) min 3.20 3.13 max 3.40 3.47 40 mV V Units
IQ
Quiescent Current
en VO - VIN
Output Noise Voltage Dropout Voltage (Note 5)
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its rated operating conditions. Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ, the junction-to-ambient thermal resistance, J-A, and the ambient temperature, TA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. The value of J-A (for devices in still air with no heatsink) is 60°C/W for the TO-220 package, 80°C/W for the TO-263 package, and 174°C/W for the SOT-223 package. The effective value of J-A can be reduced by using a heatsink (see Application Hints for specific information on heatsinking). Note 3: ESD rating is based on the human body model: 100 pF discharged through 1.5 k. Note 4: All limits guaranteed for TJ = 25°C are 100% tested and are used to calculate Outgoing Quality Levels. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. Note 5: Dropout voltage is defined as the input-output differential voltage where the regulator output drops to a value that is 100 mV below the value that is measured at VIN = 5V.
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