NSC LM2941CT, LM2941CSX, LM2941CS Datasheet

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,aquiescent current reduction circuit has
been included which reduces the ground pin current when
the differentialbetween 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 inthe dropout mode (V

IN−VOUT

≤ 3V).

Designed also for vehicular applications, the LM2941 and all
regulated circuitry are protected from reverse battery instal­lations 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 theload. Familiar regulator features such as short circuit
and thermal overload protection are also provided.

Features

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

DS008823-2

Front View

Order Number LM2941T or LM2941CT

See NS Package Number TO5A

TO-263 Surface-Mount Package

DS008823-8

DS008823-9

Order Number LM2941S or LM2941CS

See NS Package Number TS5B

16-Lead Ceramic Dual-in-Line Package

DS008823-31

Top View

Order Number LM2941J/883

5962-9166701QEA

See NS Package Number J16A

16-Lead Ceramic Surface Mount Package

DS008823-32

Front View

Order Number LM2941WG/883

5962-9166701QYA

See NS Package Number WG16A

June 1999

LM2941/LM2941C 1A Low Dropout Adjustable Regulator

© 1999 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, ≤ 100 ms)

LM2941T, LM2941S 60V

LM2941CT, LM2941CS 45V
Internal Power Dissipation (Note 3) Internally Limited
Maximum Junction Temperature 150˚C
Storage Temperature Range −65˚C ≤ T

J

≤ +150˚C

Lead Temperature

(Soldering, 10 seconds)

TO-220 (T) Package 260˚C

TO-263 (S) Package 260˚C

ESD susceptibility to be determined.

Operating Ratings

Maximum Input Voltage 26V
Temperature Range

LM2941T −40˚C ≤ T

J

≤ 125˚C

LM2941CT 0˚C ≤ T

J

≤ 125˚C

LM2941S −40˚C ≤ T

J

≤ 125˚C

LM2941CS 0˚C ≤ T

J

≤ 125˚C

LM2941J −55˚C ≤ T

J

≤ 125˚C

LM2941WG −55˚C ≤ T

J

≤ 125˚C

Electrical Characteristics—LM2941T, LM2941S, LM2941J, LM2941WG

5V ≤ VO≤ 20V, V

IN

=

V

O

+ 5V, C

O

=

22 µF, unless otherwise specified. Specifications in standard typeface apply for T

J

=

25˚C, while those in boldface type apply over the full Operating Temperature Range.

Parameter Conditions Typ

LM2941J

LM2941WG

Limit

(Note 2) (Note 4)

LM2941T
LM2941S

Limit

(Note 5)

Units

(Limits)

Reference Voltage 5 mA ≤ 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≤VIN≤ 26V, I

O

=

5 mA 4 10/10 10/10 mV/V(max)

Load Regulation 50 mA ≤ I

O

≤ 1A 7 10/10 10/10 mV/V(max)

Output Impedance 100 mADC and 20 mArms 7 mΩ/V

f

O

=

120 Hz

Quiescent Current V

O

+2V≤V

IN

<

26V, I

O

=

5 mA 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, 10 Hz–100 kHz 0.003

%

%

of V

OUT

I

O

=

5mA

Ripple Rejection f

O

=

120 Hz, 1 Vrms, I

L

=

100 mA 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

=

100 mA 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

=

100Ω,T≤100 ms

Maximum Operational
Input Voltage

31 26/26 26/26 V

DC

Reverse Polarity DC
Input Voltage

R

O

=

100Ω,V

O

≥−0.6V

−30 −15/−15 −15/−15 V(min)

Reverse Polarity
Transient Input
Voltage

T ≤ 100 ms, R

O

=

100Ω

−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 µA(max)

www.national.com 2

Electrical Characteristics—LM2941CT, LM2941CS

5V ≤ VO≤ 20V, V

IN

=

V

O

+ 5V, C

O

=

22 µF, unless otherwise specified. Specifications in standard typeface apply for T

J

=

25˚C, while those in boldface type apply over the full Operating Temperature Range.

Parameter Conditions Typ Limit Units

(Note 5) (Limits)

Reference Voltage 5 mA ≤ I

O

≤ 1A (Note 6) 1.275 1.237/1.211 V(min)

1.313/1.339 V(max)

Line Regulation V

O

+2V≤VIN≤ 26V, I

O

=

5 mA 4 10 mV/V(max)

Load Regulation 50 mA ≤ I

O

≤ 1A 7 10 mV/V(max)

Output Impedance 100 mADC and 20 mArms 7 mΩ/V

f

O

=

120 Hz

Quiescent Current V

O

+2V≤V

IN

<

26V, I

O

=

5 mA 10 15 mA(max)

V

IN

=

V

O

+ 5V, I

O

=

1A 30 45/60 mA(max)

RMS Output Noise, 10 Hz–100 kHz 0.003

%

%

of V

OUT

I

O

=

5mA

Ripple Rejection f

O

=

120 Hz, 1 Vrms, I

L

=

100 mA 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

=

100 mA 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

=

100Ω,T≤100 ms

Maximum Operational Input
Voltage

31 26 V

DC

Reverse Polarity DC Input
Voltage

R

O

=

100Ω,V

O

≥−0.6V

−30 −15 V(min)

Reverse Polarity Transient
Input Voltage

T ≤ 100 ms, R

O

=

100Ω

−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 µA(max)

Note 1: AbsoluteMaximum 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: Themaximum power dissipation is a function of T

J

(max), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is P

D

=

(T

J

-

(max) − TA)/θJA. If this dissipation is exceeded, the die temperature will rise above 150˚C and the LM2941 will go into thermal shutdown. For the LM2941T and
LM2941CT,the junction-to-ambient thermal resistance (θ

JA

) is 53˚C/W, and the junction-to-case thermal resistance (θJC) is 3˚C/W. For the LM2941K, θJAis 35˚C/W

and θ

JC

is 4˚C/W.The junction-to-ambient thermal resistance of the TO-263 is 73˚C/W, and junction-to-case thermal resistance, θJCis 3˚C. If the TO-263 package

is used, the thermalresistance can be reduced by increasing the P.C. board copper areathermally connected to the package: Using 0.5square inches of copperarea,

θ

JA

is 50˚C/W; with 1 square inch of copper area, θJAis 37˚C/W; and with 1.6 or more square inches of copper area, θJAis 32˚C/W.

Note 4: Alllimits 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: Alllimitsguaranteed at room temperature (standard typeface) andat 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.
Note 7: Output current capability will decrease with increasing temperature, but will not go below 1A at the maximum specified temperatures.

www.national.com3