1A Low Dropout Regulator
The LM2940/LM2940C positive voltage regulator features
the ability to source 1A of output current with a dropout volt-
age of typically 0.5V and a maximum of 1V over the entire
temperature range. Furthermore, a quiescent current reduc-
tion circuit has been included which reduces the ground cur-
rent 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 differ-
ential of 5V is therefore only 30 mA. Higher quiescent cur-
rents only exist when the regulator is in the dropout mode
(VIN − VOUT ≤ 3V).
Designed also for vehicular applications, the LM2940/
LM2940C and all regulated circuitry are protected from re-
verse battery installations or 2-battery jumps. During line
transients, such as load dump when the input voltage can
momentarily exceed the specified maximum operating volt-
age, 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 in-
sertion. Familiar regulator features such as short circuit and
thermal overload protection are also provided.
n Dropout voltage typically 0.5V @IO = 1A
n Output current in excess of 1A
n Output voltage trimmed before assembly
n Reverse battery protection
n Internal short circuit current limit
n Mirror image insertion protection
n P+ Product Enhancement tested
*Required if regulator 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.
0˚C ≤ TJ ≤ 125˚C
−40˚C ≤ TJ ≤ 125˚C
−40˚C ≤ TJ ≤ 85˚C
5.0 8.0 9.0 10 12 15
LM2940CT-12 LM2940CT-15 TO-220
LM2940CS-12 LM2940CS-15 TO-263
LM2940T-5.0 LM2940T-8.0 LM2940T-9.0 LM2940T-10 LM2940T-12
LM2940S-5.0 LM2940S-8.0 LM2940S-9.0 LM2940S-10 LM2940S-12
LM2940IMP-5.0 LM2940IMP-8.0 LM2940IMP-9.0 LM2940IMP-10 LM2940IMP-12 LM2940IMP-15 SOT-223
LM2940IMPX-5.0 LM2940IMPX-8.0 LM2940IMPX-9.0 LM2940IMPX-10 LM2940IMPX-12 LM2940IMPX-15 SOT-223
The physical size of the SOT-223 is too small to contain the full device part number. The package markings indicated are what will appear on the actual device.
−55˚C ≤ TJ ≤ 125˚C
For information on military temperature range products, please go to the Mil/Aero Web Site at http://www.national.com/appinfo/milaero/index.html.
© 2000 National Semiconductor Corporation DS008822