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 temper-
ature range. Furthermore, a quiescent current reduction cir-
cuit has been included which reduces the 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 (V
IN
− V
OUT
≤
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 can-
not be harmed by temporary mirror-image insertion. Familiar
regulator features such as short circuit and thermal overload
protection are also provided.
Features
■
■
■
■
■
■
■
Dropout voltage typically 0.5V @I
O
= 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
882203
*Required if regulator is located far from power supply filter.
**C
OUT
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 Voltage
5.0
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
≤
T
J
≤
125°C
LM2940LD-5.0
−40°C
LM2940LD-8.0
LM2940LD-9.0
LM2940LD-10
LM2940LD-12
LLP
1k Units
LM2940LD-15
Tape and
Reel
LLP
4.5k
Units
Tape and
Reel
TO-220
TO-263
≤
T
J
≤
125°C
LM2940LDX
-5.0
LM2940LDX
-8.0
LM2940LDX
-9.0
LM2940LDX
-10
LM2940LDX
-12
LM2940LDX
-15
–
–
–
−40°C
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
≤
T
J
≤
125°C
© 2007 National Semiconductor Corporation
8822
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
