LM2941/LM2941C
1A Low Dropout Adjustable Regulator
General Description
The LM2941 positive voltage regulator features the ability to
source 1A of output current with a typical dropout voltage of
0.5V and a maximum of 1V over the entire temperature
range. Furthermore, a quiescent current reduction circuit has
been included which reduces the ground pin 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 LM2941 and all
regulated circuitry are protected from reverse battery instal-
lations or two-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. Familiar regulator features such as short circuit
and thermal overload protection are also provided.
Features
n
LLP space saving package
n
Output voltage adjustable from 5V to 20V
n
Dropout voltage typically 0.5V
@
I
O
= 1A
n
Output current in excess of 1A
n
Trimmed reference voltage
n
Reverse battery protection
n
Internal short circuit current limit
n
Mirror image insertion protection
n
P
+
Product Enhancement tested
n
TTL, CMOS compatible ON/OFF switch
Connection Diagram and Ordering Information
TO-220 Plastic Package
TO-263 Surface-Mount Package
00882302
Tep View
Order Number LM2941T or
LM2941CT
See NS Package Number TO5A
00882308
Order Number LM2941S, LM2941SX
or LM2941CS, LM2941CSX
See NS Package Number TS5B
00882309
16-Lead Ceramic Dual-in-Line
Package
16-Lead Ceramic Surface Mount
Package
8-Lead LLP Surface Mount
Package
00882331
Top View
Order Number LM2941J/883
LM2941J-QMLV, 5962-9166701QEA
See NS Package Number J16A
00882332
Top View
Order Number LM2941WG/883
LM2941WG-QMLV,
5962-9166701QYA
See NS Package Number WG16A
00882333
Top View
Ordering Number LM2941LD,
LM2941LDX
See NS Package Number LDC08A
August 2002
LM2941/LM2941C
1A
Low
Dropout
Adjustable
Regulator
2002 National Semiconductor Corporation
DS008823
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Voltage (Survival Voltage,
100ms)
LM2941T, LM2941S, LM2941LD
60V
LM2941CT, LM2941CS
45V
Internal Power Dissipation (Note 3)
Internally Limited
Maximum Junction Temperature
150C
Storage Temperature Range
-65C
T
J
+150C
Lead Temperature
(Soldering, 10 seconds)
TO-220 (T) Package
260C
TO-263 (S) Package
260C
ESD susceptibility to be determined.
Operating Ratings
Maximum Input Voltage
26V
Temperature Range
LM2941T
-40C
T
J
125C
LM2941CT
0C
T
J
125C
LM2941S
-40C
T
J
125C
LM2941CS
0C
T
J
125C
LM2941J
-55C
T
J
125C
LM2941WG
-55C
T
J
125C
LM2941LD
-40C
T
J
125C
Electrical Characteristics--LM2941T, LM2941S, LM2941J, LM2941WG,
LM2941LD
5V
V
O
20V, V
IN
= V
O
+ 5V, C
O
= 22F, unless otherwise specified. Specifications in standard typeface apply for T
J
=
25C, while those in boldface type apply over the full Operating Temperature Range.
Parameter
Conditions
Typ
LM2941J
LM2941WG
Limit
(Note 2) (Note 4)
LM2941T
LM2941S
LM2941LD
Limit
(Note 5)
Units
(Limits)
Reference Voltage
5mA
I
O
1A (Note 6)
1.275
1.237/1.211
1.237/1.211
V(min)
1.313/1.339
1.313/1.339
V(max)
Line Regulation
V
O
+ 2V
V
IN
26V, I
O
= 5mA
4
10/10
10/10
mV/V(max)
Load Regulation
50mA
I
O
1A
7
10/10
10/10
mV/V(max)
Output Impedance
100 mADC and 20 mArms
7
m
/V
f
O
= 120Hz
Quiescent Current
V
O
+ 2V
V
IN
<
26V, I
O
= 5mA
10
15/20
15/20
mA(max)
V
IN
= V
O
+ 5V, I
O
= 1A
30
45/60
45/60
mA(max)
RMS Output Noise,
10Hz100kHz
0.003
%
% of V
OUT
I
O
= 5mA
Ripple Rejection
f
O
= 120Hz, 1 Vrms, I
L
= 100mA
0.005
0.02/0.04
0.02/0.04
%/V(max)
Long Term Stability
0.4
%/1000 Hr
Dropout Voltage
I
O
= 1A
0.5
0.8/1.0
0.8/1.0
V(max)
I
O
= 100mA
110
200/200
200/200
mV(max)
Short Circuit Current
V
IN
Max = 26V (Note 7)
1.9
1.6/1.3
1.6
A(min)
Maximum Line
V
O
Max 1V Above Nominal V
O
75
60/60
60/60
V(min)
Transient
R
O
= 100, T
100ms
Maximum Operational
Input Voltage
31
26/26
26/26
V
DC
Reverse Polarity DC
Input Voltage
R
O
= 100, V
O
-0.6V
-30
-15/-15
-15/-15
V(min)
Reverse Polarity
Transient Input Voltage
T
100ms, R
O
= 100
-75
-50/-50
-50/-50
V(min)
ON/OFF Threshold
Voltage ON
I
O
1A
1.30
0.80/0.80
0.80/0.80
V(max)
ON/OFF Threshold
Voltage OFF
I
O
1A
1.30
2.00/2.00
2.00/2.00
V(min)
ON/OFF Threshold
Current
V
ON/OFF
= 2.0V, I
O
1A
50
100/300
100/300
A(max)
LM2941/LM2941C
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2
Electrical Characteristics--LM2941CT, LM2941CS
5V
V
O
20V, V
IN
= V
O
+ 5V, C
O
= 22F, unless otherwise specified. Specifications in standard typeface apply for T
J
=
25C, while those in boldface type apply over the full Operating Temperature Range.
Parameter
Conditions
Typ
Limit
Units
(Note 5)
(Limits)
Reference Voltage
5mA
I
O
1A (Note 6)
1.275
1.237/1.211
V(min)
1.313/1.339
V(max)
Line Regulation
V
O
+ 2V
V
IN
26V, I
O
= 5mA
4
10
mV/V(max)
Load Regulation
50mA
I
O
1A
7
10
mV/V(max)
Output Impedance
100 mADC and 20 mArms
7
m
/V
f
O
= 120Hz
Quiescent Current
V
O
+ 2V
V
IN
<
26V, I
O
= 5mA
10
15
mA(max)
V
IN
= V
O
+ 5V, I
O
= 1A
30
45/60
mA(max)
RMS Output Noise,
10Hz100kHz
0.003
%
% of V
OUT
I
O
= 5mA
Ripple Rejection
f
O
= 120Hz, 1 Vrms, I
L
= 100mA
0.005
0.02
%/V(max)
Long Term Stability
0.4
%/1000 Hr
Dropout Voltage
I
O
= 1A
0.5
0.8/1.0
V(max)
I
O
= 100mA
110
200/200
mV(max)
Short Circuit Current
V
IN
Max = 26V (Note 7)
1.9
1.6
A(min)
Maximum Line
V
O
Max 1V Above Nominal V
O
55
45
V(min)
Transient
R
O
= 100
, T 100ms
Maximum Operational Input
Voltage
31
26
V
DC
Reverse Polarity DC Input
Voltage
R
O
= 100
, V
O
-0.6V
-30
-15
V(min)
Reverse Polarity Transient
Input Voltage
T
100ms, R
O
= 100
-55
-45
V(min)
ON/OFF Threshold Voltage
ON
I
O
1A
1.30
0.80
V(max)
ON/OFF Threshold Voltage
OFF
I
O
1A
1.30
2.00
V(min)
ON/OFF Threshold Current
V
ON/OFF
= 2.0V, I
O
1A
50
100
A(max)
Thermal Performance
Thermal Resistance
Junction-to-Case
5-Lead TO-220
3
C/W
5-Lead TO-263
3
C/W
Thermal Resistance
Junction-to-Ambient
5-Lead TO-220
53
C/W
5-Lead TO-263
73
C/W
8-Lead LLP (Note 3)
35
C/W
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions for which the device is
intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see
the Electrical Characteristics.
Note 2: A military RETS specification available upon request. For more information about military-aerospace products, see the Mil-Aero web page at
http://www.national.com/appinfo/milaero/index.html.
Note 3: The maximum power dissipation is a function of T
J
(max),
JA
, and T
A
. The maximum allowable power dissipation at any ambient temperature is P
D
=
(T
J
(max) - T
A
)/
JA
. If this dissipation is exceeded, the die temperature will rise above 150C and the LM2941 will go into thermal shutdown. If the TO-263 package
is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 square inches of copper
area,
JA
is 50C/W; with 1 square inch of copper area,
JA
is 37C/W; and with 1.6 or more square inches of copper area,
JA
is 32C/W. Thermal performance for
the LLP package was obtained using a JESD51-7 board with six vias, using no airflow and an ambient temperature of 22C. The value
JA
for the LLP package is
specifically dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for the
LLP package, refer to Application Note AN-1187. It is recommended that 6 vias be placed under the center pad to improve thermal performance.
Note 4: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All limits are used to calculate Outgoing Quality
Level, and are 100% production tested.
Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
Note 6: The output voltage range is 5V to 20V and is determined by the two external resistors, R1 and R2. See Typical Application Circuit.
LM2941/LM2941C
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3
Thermal Performance
(Continued)
Note 7: Output current capability will decrease with increasing temperature, but will not go below 1A at the maximum specified temperatures.
Typical Performance Characteristics
Dropout Voltage
Dropout Voltage vs. Temperature
00882311
00882312
Output Voltage
Quiescent Current vs. Temperature
00882313
00882314
Quiescent Current
Quiescent Current
00882315
00882316
LM2941/LM2941C
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4
Typical Performance Characteristics
(Continued)
Line Transient Response
Load Transient Response
00882317
00882318
Ripple Rejection
Output Impedance
00882319
00882320
Low Voltage Behavior
Low Voltage Behavior
00882321
00882322
LM2941/LM2941C
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5
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