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LM2940/LM2940C 1A Low Dropout Regulator

January 2007

LM2940/LM2940C 1A Low Dropout Regulator
General Description
The LM2940/LM2940C positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0.5V and a maximum of 1V over the entire temperature range. Furthermore, a quiescent current reduction circuit has been included which reducesthe ground current when the differential between the input voltage and the output voltage exceeds approximately 3V. The quiescent current with 1A of output current and an input-output differential of 5V is therefore only 30 mA. Higher quiescent currents only exist when the regulator is in the dropout mode (VIN − VOUT ≤ 3V). Designed also for vehicular applications, the LM2940/ LM2940C and allregulated circuitry are protected from reverse battery installations or 2-battery jumps. During line transients, such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both the internal circuits and the load. The LM2940/LM2940C cannot be harmed by temporary mirror-image insertion. Familiar regulatorfeatures such as short circuit and thermal overload protection are also provided.

■ ■ ■ ■ ■ ■ ■
Dropout voltage typically 0.5V @IO = 1A Output current in excess of 1A Output voltage trimmed before assembly Reverse battery protection Internal short circuit current limit Mirror image insertion protection P+ Product Enhancement tested

Typical Application


*Required ifregulator is located far from power supply filter. **COUT must be at least 22 μF to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to the regulator. This capacitor must be rated over the same operating temperature range as the regulator and the ESR is critical; see curve.

Ordering Information
Temp Range 0°C Output Voltage5.0 LM2940CT-5.0 LM2940CS-5.0 LM2940CSX -5.0 8.0 – – – 9.0 LM2940CT-9.0 LM2940CS-9.0 LM2940CSX -9.0 10 – – – 12 LM2940CT-12 LM2940CS-12 LM2940CSX -12 15 LM2940CT-15 LM2940CS-15 LM2940CSX -15 TO-263 Package TO-220

≤ TJ ≤

LM2940LD-5.0 −40°C





LLP 1k Units LM2940LD-15 Tape and Reel LLP 4.5k Units Tape and Reel TO-220 TO-263≤ TJ ≤
125°C LM2940LDX -5.0 LM2940LDX -8.0 LM2940LDX -9.0 LM2940LDX -10 LM2940LDX -12 LM2940LDX -15 – – –


LM2940T-5.0 LM2940S-5.0 LM2940SX-5.0

LM2940T-8.0 LM2940S-8.0 LM2940SX-8.0

LM2940T-9.0 LM2940S-9.0 LM2940SX-9.0

LM2940T-10 LM2940S-10 LM2940SX-10

LM2940T-12 LM2940S-12 LM2940SX-12

≤ TJ ≤

© 2007 National Semiconductor Corporation


www.national.com LM2940/LM2940C

Temp Range −40°C

Output Voltage 5.0 8.0 9.0 10 12 15


LM2940IMP-5.0 LM2940IMP-8.0 LM2940IMP-9.0 LM2940IMP-10 LM2940IMP-12 LM2940IMP-15 SOT-223 LM2940IMPX -5.0 L53B LM2940IMPX -8.0 L54B LM2940IMPX -9.0 L0EB LM2940IMPX -10 L55B LM2940IMPX -12 L56B LM2940IMPX -15 L70B SOT-223 in Tape and Reel

≤ TA ≤
85°C Marking

The physical size of the SOT-223 is toosmall to contain the full device part number. The package markings indicated are what will appear on the actual device.

Mil-Aero Ordering Information Temperature Range −55°C Output Voltage 5.0 LM2940J-5.0/883 5962-8958701EA LM2940WG5.0/883 5962-8958701XA 8.0 – – 12 LM2940J-12/883 5962-9088401QEA LM2940WG5-12/883 15 LM2940J-15/883 5962-9088501QEA LM2940WG5-15/883 Package J16A WG16A

≤ TJ ≤
125°CFor information on military temperature range products, please go to the Mil/Aero Web Site at http://www.national.com/appinfo/milaero/index.html.

Connection Diagrams
TO-220 (T) Plastic Package SOT-223 (MP) 3-Lead


Front View See NS Package Number TO3B 16-Lead Dual-in-Line Package (J)


Front View See NS Package Number MP04A 16-Lead Ceramic Surface-Mount Package...
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