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LM2941, LM2941C
SNVS770I – JUNE 1999 – REVISED JANUARY 2015
LM2941x 1-A Low Dropout Adjustable Regulator
1 Features
3 Description
•
•
•
•
•
•
•
•
•
•
•
The LM2941 positive voltage regulator features the
ability to source 1 A of output current with a typical
dropout voltage of 0.5 V and a maximum of 1 V 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 3 V. The quiescent
current with 1 A of output current and an input-output
differential of 5 V is therefore only 30 mA. Higher
quiescent currents only exist when the regulator is in
the dropout mode (VIN − VOUT ≤ 3 V).
1
Operating VIN Range: 6 V to 26 V
Output Voltage Adjustable From 5 V to 20 V
Dropout Voltage Typically 0.5 V at IOUT = 1 A
Output Current in Excess of 1 A
Trimmed Reference Voltage
Reverse Battery Protection
Internal Short-Circuit Current Limit
Mirror Image Insertion Protection
P+ Product Enhancement Tested
TTL, CMOS Compatible ON/OFF Switch
WSON Space-Saving Package
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 the load.
Familiar regulator features such as short circuit and
thermal overload protection are also provided.
2 Applications
•
•
Industrial
Automotive
Device Information(1)
PART NUMBER
LM2941
LM2941C
PACKAGE
BODY SIZE (NOM)
WSON (8)
4.00 mm x 4.00 mm
TO-263 (5)
10.16 mm x 8.42 mm
TO-220 (5)
14.986 mm x 10.16 mm
TO-220 (5)
10.16 mm x 8.51 mm
TO-263 (5)
10.16 mm x 8.42 mm
TO-220 (5)
14.986 mm x 10.16 mm
TO-220 (5)
10.16 mm x 8.51 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
VIN
VOUT
LM2941
6 V to 26 V
CIN
470 nF
IN
5 V to 20 V
OUT
R2
ON/OFF
ADJ
COUT
22 µF
LOAD
R1
GND
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM2941, LM2941C
SNVS770I – JUNE 1999 – REVISED JANUARY 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
4
4
4
5
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics: LM2941T, LM2941S,
LM2941LD..................................................................
6.6 Electrical Characteristics: LM2941CT, LM2941CS...
6.7 Typical Characteristics ..............................................
7
5
6
7
Detailed Description ............................................ 10
7.1
7.2
7.3
7.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
10
10
10
11
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Application .................................................. 12
9 Power Supply Recommendations...................... 14
10 Layout................................................................... 14
10.1
10.2
10.3
10.4
Layout Guidelines .................................................
Layout Example ....................................................
Power Dissipation .................................................
Thermal Considerations ........................................
14
14
16
17
11 Device and Documentation Support ................. 18
11.1
11.2
11.3
11.4
11.5
11.6
Device Support ....................................................
Documentation Support .......................................
Related Links ........................................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
18
19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision H (December 2014) to Revision I
•
Changed update pin names to TI nomenclature ................................................................................................................... 1
Changes from Revision G (April 2013) to Revision H
•
2
Page
Added Device Information and ESD Ratings tables, Feature Description section, Device Functional Modes,
Application and Implementation section, Power Supply Recommendations section, Layout section, Device and
Documentation Support section, and Mechanical, Packaging, and Orderable Information section; updated Thermal Info .. 1
Changes from Revision F (April 2013) to Revision G
•
Page
Page
Changed layout of National Data Sheet to TI format ............................................................................................................. 1
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5 Pin Configuration and Functions
TO-220 (KC) Plastic Package
4 Pins
Top View
TO-263 (KTT) Surface-Mount Package
4 Pins
WSON (NGN)Surface Mount Package
8 Leads
Top View
ON/OFF
1
GND
2
8
ADJ
7
GND
GND*
INPUT
3
6
N/C
N/C
4
5
OUTPUT
* TIE TO GND OR LEAVE FLOATING
Pin Functions
PIN
NAME
TYPE
DESCRIPTION
KC
KTT
NGN
ADJ
1
1
8
ON/OFF
2
2
GND
3
3
IN
4
4
3
I
Input supply
OUT
5
5
5
O
Regulated output voltage. This pin requires an output capacitor to
maintain stability. See the Detailed Design Procedure section for
output capacitor details.
NC
—
—
4, 6
—
No internal connection. Connect to GND or leave open.
I
Sets output voltage
1
I
Enable/Disable control
2, 7
—
Ground
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6 Specifications
6.1 Absolute Maximum Ratings (1) (2)
MIN
Input voltage (Survival Voltage, ≤ 100 ms)
Internal power dissipation
MAX
UNIT
LM2941T, LM2941S, LM2941LD
60
V
LM2941CT, LM2941CS
45
V
(3)
Internally Limited
Maximum junction temperature
Soldering remperature (4)
150
°C
TO-220 (T), Wave, 10 s
260
°C
TO-263 (S), 30 s
235
°C
235
°C
150
°C
WSON-8 (LD), 30 s
−65
Storage temperature, Tstg
(1)
(2)
(3)
(4)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
The maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(max) − TA)/RθJA. If this dissipation is exceeded, the die temperature will rise above 150°C and the LM2941 will
go into thermal shutdown. If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper
area thermally connected to the package. The value RθJA for the WSON 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 WSON package,
refer to Application Note AN-1187 (SNOA401). It is recommended that 6 vias be placed under the center pad to improve thermal
performance.
Refer to JEDEC J-STD-020C for surface mount device (SMD) package reflow profiles and conditions. Unless otherwise stated, the
temperature and time are for Sn-Pb (STD) only.
6.2 ESD Ratings
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
VALUE
UNIT
±2000
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
LM2941T
LM2941CT
Temperatures
4
MIN
MAX
−40
125
0
125
−40
125
LM2941CS
0
125
LM2941LD
−40
125
LM2941S
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UNIT
°C
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6.4 Thermal Information
LM2941LD
THERMAL METRIC
(1) (2)
LM2941S, LM2941T
WSON
(NGN)
TO-263
(KTT)
TO-220
(KC)
8 PINS
5 PINS
5 PINS
RθJA
Junction-to-ambient thermal resistance
40.5
41
32.1
RθJC(top)
Junction-to-case (top) thermal resistance
26.2
43.2
25.6
RθJB
Junction-to-board thermal resistance
17
22.9
18.3
ψJT
Junction-to-top characterization parameter
0.2
11.4
8.5
ψJB
Junction-to-board characterization parameter
17.2
21.9
17.7
RθJC(bot)
Junction-to-case (bottom) thermal resistance
3.2
0.9
0.7
(1)
(2)
UNIT
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
The maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(max) − TA)/RθJA. If this dissipation is exceeded, the die temperature will rise above 150°C and the LM2941 will
go into thermal shutdown. If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper
area thermally connected to the package. The value RθJA for the WSON 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 WSON package,
refer to Application Note AN-1187 (SNOA401). It is recommended that 6 vias be placed under the center pad to improve thermal
performance.
6.5 Electrical Characteristics: LM2941T, LM2941S, LM2941LD
5 V ≤ VOUT ≤ 20 V, VIN = VOUT + 5 V, COUT = 22 μF, unless otherwise specified. MIN (minimum) and MAX (maximum)
specifications in apply over the full Operating Temperature Range (unless otherwise specified) and typical values apply at TJ
= 25°C.
PARAMETER
Reference voltage
TEST CONDITIONS
5 mA ≤ IOUT ≤ 1 A
(1)
5 mA ≤ IOUT ≤ 1 A (1), TJ = 25°C
MIN
TYP
MAX
1.211
1.275
1.339
1.237
1.275
1.313
UNIT
V
Line regulation
VOUT + 2 V ≤ VIN ≤ 26 V, IOUT = 5 mA
4
10
mV/V
Load regulation
50 mA ≤ IOUT ≤ 1 A
7
10
mV/V
Output impedance
100 mADC and 20 mArms, ƒOUT = 120 Hz
Quiescent current
RMS output noise, % of VOUT
Ripple rejection
7
10
20
VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA, TJ =
25°C
10
15
VIN = VOUT + 5 V, IOUT = 1 A
30
60
VIN = VOUT + 5 V, IOUT = 1 A, TJ = 25°C
30
45
10 Hz to 100 kHz, IOUT = 5 mA
0.005
0.04
ƒOUT = 120 Hz, 1 Vrms, IL = 100 mA, TJ = 25°C
0.005
0.02
0.4
0.5
1
IOUT = 1 A, TJ = 25°C
0.5
0.8
IOUT = 100 mA
110
200
Short-circuit current
VIN max = 26 V
Maximum line transient
VOUT max 1 V above nominal VOUT
ROUT = 100 Ω, t ≤ 100 ms
Maximum operational input
voltage
1.6
60
%/V
V
mV
1.9
A
75
26
31
Reverse polarity
DC input voltage
ROUT = 100 Ω, VOUT ≥ −0.6 V
−15
−30
Reverse polarity
transient input voltage
t ≤ 100 ms, ROUT = 100 Ω
−50
−75
(1)
(2)
mA
%/1000 Hr
IOUT = 1 A
(2)
mA
0.003%
ƒOUT = 120 Hz, 1 Vrms, IL = 100 mA
Long-term stability
Dropout voltage
mΩ/V
VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA
V
VDC
V
The output voltage range is 5 V to 20 V and is determined by the two external resistors, R1 and R2. See Figure 18.
Output current capability will decrease with increasing temperature, but will not go below 1 A at the maximum specified temperatures.
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Electrical Characteristics: LM2941T, LM2941S, LM2941LD (continued)
5 V ≤ VOUT ≤ 20 V, VIN = VOUT + 5 V, COUT = 22 μF, unless otherwise specified. MIN (minimum) and MAX (maximum)
specifications in apply over the full Operating Temperature Range (unless otherwise specified) and typical values apply at TJ
= 25°C.
PARAMETER
TEST CONDITIONS
ON/OFF threshold
voltage ON
IOUT ≤ 1 A
ON/OFF threshold
voltage OFF
IOUT ≤ 1 A
ON/OFF threshold
current
MIN
TYP
MAX
1.30
0.80
UNIT
V
2
1.3
VON/OFF = 2 V, IOUT ≤ 1 A
50
300
VON/OFF = 2 V, IOUT ≤ 1 A, TJ = 25°C
50
100
μA
6.6 Electrical Characteristics: LM2941CT, LM2941CS
5 V ≤ VOUT ≤ 20 V, VIN = VOUT + 5 V, COUT = 22 μF, unless otherwise specified. MIN (minimum) and MAX (maximum)
specifications in apply over the full Operating Temperature Range (unless otherwise specified) and typical values apply at TJ
= 25°C.
PARAMETER
Reference voltage
MIN
TYP
MAX
5 mA ≤ IOUT ≤ 1 A (1)
TEST CONDITIONS
1.211
1.275
1.339
5 mA ≤ IOUT ≤ 1 A (1), TJ = 25°C
1.237
1.275
1.313
Line regulation
VOUT + 2 V ≤ VIN ≤ 26 V, IOUT = 5 mA, TJ =
25°C
4
10
Load regulation
50 mA ≤ IOUT ≤ 1 A, TJ = 25°C
7
10
Output impedance
100 mADC and 20 mArms, ƒOUT = 120 Hz
7
VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA, TJ =
25°C
10
15
VIN = VOUT + 5 V, IOUT = 1 A
30
60
VIN = VOUT + 5 V, IOUT = 1 A, TJ = 25°C
30
45
Quiescent current
RMS output noise, % of VOUT
10 Hz to 100 kHz
IOUT = 5 mA
Ripple rejection
ƒOUT = 120Hz, 1 Vrms, IL = 100 mA, TJ = 25°C
0.005
0.02
0.4
mV/V
mA
mA
1
IOUT = 1A, TJ = 25°C
0.5
0.8
110
200
VIN max = 26 V (2), TJ = 25°C
Maximum line transient
VOUT max 1 V above nominal VOUT, ROUT = 100
Ω, t ≤ 100 ms, , TJ = 25°C
45
Maximum operational input
voltage
TJ = 25°C
26
31
Reverse polarity
DC input voltage
ROUT = 100 Ω, VOUT ≥ −0.6 V, TJ = 25°C
−15
−30
Reverse polarity
transient input voltage
t ≤ 100 ms, ROUT = 100 Ω, TJ = 25°C
−45
−55
ON/OFF threshold
voltage ON
IOUT ≤ 1 A, TJ = 25°C
ON/OFF threshold
voltage OFF
IOUT ≤ 1 A, TJ = 25°C
ON/OFF threshold
current
VON/OFF = 2 V, IOUT ≤ 1 A, TJ = 25°C
1.6
%/V
%/1000 Hr
0.5
IOUT = 100 mA
6
mV/V
mΩ/V
IOUT = 1A
Short-circuit current
(1)
(2)
V
0.003%
Long-term stability
Dropout voltage
UNIT
1.9
V
mV
A
55
V
VDC
V
1.3
0.8
V
2
1.3
50
100
μA
The output voltage range is 5 V to 20 V and is determined by the two external resistors, R1 and R2. See Typical Application.
Output current capability will decrease with increasing temperature, but will not go below 1 A at the maximum specified temperatures.
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6.7 Typical Characteristics
Figure 1. Dropout Voltage
Figure 2. Dropout Voltage vs. Temperature
Figure 3. Output Voltage
Figure 4. Quiescent Current vs. Temperature
Figure 5. Quiescent Current
Figure 6. Quiescent Current
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Typical Characteristics (continued)
8
Figure 7. Line Transient Response
Figure 8. Load Transient Response
Figure 9. Ripple Rejection
Figure 10. Output Impedance
Figure 11. Low Voltage Behavior
Figure 12. Low Voltage Behavior
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Typical Characteristics (continued)
Figure 13. Output Capacitor ESR
Figure 14. Output at Voltage Extremes
Figure 15. Output at Voltage Extremes
Figure 16. Peak Output Current
Figure 17. Maximum Power Dissipation (TO-220)
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7 Detailed Description
7.1 Overview
The LM2941 positive voltage regulator features the ability to source 1 A of output current with a dropout voltage
of typically 0.5 V and a maximum of 1 V over the entire temperature range. Furthermore, a quiescent current
reduction circuit has been included which reduces the ground current when the differential between the input
voltage and the output voltage exceeds approximately 3 V. The quiescent current with 1 A of output current and
an input-output differential of 5 V is therefore only 30 mA. Higher quiescent currents only exist when the regulator
is in the dropout mode (VIN – VOUT ≤ 3 V).
7.2 Functional Block Diagram
OUT
IN
PNP
OVSD
(≈ 30 V)
Current
Limit
Thermal
Shutdown
ON/OFF
+
Bandgap
Reference
ADJ
LM2941
GND
7.3 Feature Description
7.3.1 Short-Circuit Current Limit
The internal current limit circuit is used to protect the LDO against high-load current faults or shorting events. The
LDO is not designed to operate in a steady-state current limit. During a current-limit event, the LDO sources
constant current. Therefore, the output voltage falls when load impedance decreases. Note also that if a current
limit occurs and the resulting output voltage is low, excessive power may be dissipated across the LDO, resulting
a thermal shutdown of the output.
7.3.2 Overvoltage Shutdown (OVSD)
Input voltage greater than typically 30 V will cause the LM2941 output to be disabled. When operating with the
input voltage greater than the maximum recommended input voltage of 26 V, the device performance is not
ensured. Continuous operation with the input voltage greater than the maximum recommended input voltage is
discouraged.
10
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Feature Description (continued)
7.3.3 Thermal Shutdown (TSD)
The LM2941 contains the thermal shutdown circuitry to turn off the output when excessive heat is dissipated in
the LDO. The internal protection circuitry of the LM2941 is designed to protect against thermal overload
conditions. The TSD circuitry is not intended to replace proper heat sinking. Continuously running the device into
thermal shutdown degrades its reliability as the junction temperature will be exceeding the absolute maximum
junction temperature rating.
7.3.4 Thermal Overload Protection
The LM2941 incorporates a linear form of thermal protection that limits the junction temperature (TJ) to typically
155°C.
Should the LM2941 see a fault condition that results in excessive power dissipation and the junction temperature
approaches 155°C, the device will respond by reducing the output current (which reduces the power dissipation)
to hold the junction temperature at 155°C.
Thermal Overload protection is not an ensured operating condition. Operating at, or near to, the thermal overload
condition for any extended period of time is not encouraged, or recommended, as this may shorten the lifetime of
the device.
7.4 Device Functional Modes
7.4.1 Operation With ON/OFF Control
The ON/OFF pin has no internal pull-up or pull-down to establish a default condition and, as a result, this pin
must be terminated externally, either actively or passively. The ON/OFF pin requires a low level to enable the
output, and a high level to disable the output. To ensure reliable operation, the ON/OFF pin voltage must rise
above the maximum ON/OFF(OFF) voltage threshold (2 V) to disable the output, and must fall below the
minimum ON/OFF(ON) voltage threshold (0.8 V) to enable the output. If the ON/OFF function is not needed this
pin can be connected directly to Ground. If the ON/OFF pin is being pulled to a high state through a series
resistor, an allowance must be made for the ON/OFF pin current that will cause a voltage drop across the pull-up
resistor
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
Figure 18 shows the typical application circuit for the LM2941. The output capacitor, COUT, must have a
capacitance value of at least 22 µF with an equivalent series resistance (ESR) of at least 100 mΩ, but no more
than 1 Ω. The minimum capacitance value and the ESR requirements apply across the entire expected operating
ambient temperature range.
8.2 Typical Application
Note: Using 1 kΩ for R1 will ensure that the bias current error from the adjust pin will be negligible. Do not bypass R1
or R2. This will lead to instabilities.
* 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.
Figure 18. 5-V to 20-V Adjustable Regulator
8.2.1 Design Requirements
12
DESIGN PARAMETER
EXAMPLE VALUE
Input voltage range
10 V to 26 V
Output voltage
15 V
Output current range
5 mA to 1 A
Input capacitor value
0.47 µF
Output capacitor value
22 µF minimum
Output capacitor ESR range
100 mΩ to 1 Ω
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8.2.2 Detailed Design Procedure
8.2.2.1 Output Capacitor
A tantalum capacitor with a minimum capacitance value of 22 μF, and ESR in the range of 0.01 Ω to 5 Ω, is
required at the output pin for loop stability. It must be located less than 1 cm from the device. There is no
limitation on any additional capacitance.
Alternately, a high quality X5R/X7R 22 μF ceramic capacitor may be used for the output capacitor only if an
appropriate value of series resistance is added to simulate the ESR requirement. The ceramic capacitor selection
must include an appropriate voltage de-rating of the capacitance value due to the applied output voltage. The
series resistor (for ESR simulation) should be in the range of 0.1 Ω to 1 Ω.
8.2.2.2 Setting the Output Voltage
The output voltage range is 5 V to 20 V and is set by the two external resistors, R1 and R2. See the Figure 18.
The output voltage is given by the formula:
VOUT = VREF × ((R1 + R2) / R1)
where
•
VREF is typically 1.275 V
(1)
Using 1 kΩ for R1 will ensure that the bias current error of the adjust pin will be negligible. Using a R1 value
higher than 10 kΩ may cause the output voltage to shift across temperature due to variations in the adjust pin
bias current.
Calculating the upper resistor (R2) value of the pair when the lower resistor (R1) value is known is accomplished
with the following formula:
R2 = R1 × ((VOUT / VREF) – 1)
(2)
The resistors used for R1 and R2 should be high quality, tight tolerance, and with matching temperature
coefficients. It is important to remember that, although the value of VREF is ensured, the final value of VOUT is not.
The use of low quality resistors for R1 and R2 can easily produce a VOUT value that is unacceptable.
8.2.3 Application Curves
Figure 19. Low Voltage Behavior
Figure 20. Output at Voltage Extremes
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9 Power Supply Recommendations
The device is designed to operate from an input voltage supply range between VOUT + 1 V up to a maximum of
26 V. This input supply must be well regulated and free of spurious noise. To ensure that the LM2941 output
voltage is well regulated, the input supply should be at least VOUT + 2 V.
10 Layout
10.1 Layout Guidelines
The dynamic performance of the LM2941 is dependent on the layout of the PCB. PCB layout practices that are
adequate for typical LDOs may degrade the PSRR, noise, or transient performance of the LM2941. Best
performance is achieved by placing CIN and COUT on the same side of the PCB as the LM2941, and as close as
is practical to the package. The ground connections for CIN and COUT should be back to the LM2941 ground pin
using as wide and short of a copper trace as is practical.
10.2 Layout Example
ON/OFF
ADJ
Thermal Vias
GND
GND
R1
IN
GND
NC
R2
CIN
OUT
NC
COUT
GND
Figure 21. LM2941 WSON Package Typical Layout
14
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Layout Example (continued)
IN
OUT
GND
ADJ
ON/OFF
GND
GND
COUT
CIN
R2
R1
Figure 22. LM2941 TO-220 Package Typical Layout
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Layout Example (continued)
OUT
IN
GND
ON/OFF
ADJ
GND
COUT
CIN
R2
R1
Figure 23. LM2941 TO-263 Package Typical Layout
10.3 Power Dissipation
Consideration should be given to the maximum power dissipation (PD(MAX)) which is limited by the maximum
operating junction temperature (TJ(MAX)) of 125°C, the maximum operating ambient temperature (TA(MAX)) of the
application, and the thermal resistance (RθJA) of the package. Under all possible conditions, the junction
temperature (TJ) must be within the range specified in the Operating Ratings. The total power dissipation of the
device is given by:
PD = ( (VIN − VOUT) x IOUT) + (VIN x IGND)
(3)
where IGND is the operating ground pin current of the device (specified under Electrical Characteristics: LM2941T,
LM2941S, LM2941LD and Electrical Characteristics: LM2941CT, LM2941CS).
The maximum allowable junction temperature rise (ΔTJ) depends on the maximum expected ambient
temperature (TA(MAX)) of the application, and the maximum allowable junction temperature (TJ(MAX)):
ΔTJ = TJ(MAX) − TA(MAX)
(4)
The maximum allowable value for junction to ambient Thermal Resistance, RθJA, required to keep the junction
temperature, TJ, from exceeding maximum allowed can be calculated using the formula:
RθJA = ΔTJ / PD(MAX)
(5)
The maximum allowable power dissipation, PD(MAX), required allowed for a specific ambient temperature can be
calculated using the formula:
PD(MAX) = ΔTJ / RθJA
(6)
Additional information for thermal performance of surface mount packages can be found in AN-1520: A Guide to
Board Layout for Best Thermal Resistance for Exposed Packages (SNVA183), AN-1187: Leadless Leadframe
Package (LLP) (SNOA401), and AN-2020: Thermal Design By Insight, Not Hindsight (SNVA419).
16
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10.4 Thermal Considerations
10.4.1 TO-263 Mounting
The thermal dissipation of the TO-263 package is directly related to the printed circuit board construction and the
amount of additional copper area connected to the TAB.
The TAB on the bottom of the TO-263 package is connected to the die substrate via a conductive die attach
adhesive, and to device pin 3. As such, it is strongly recommend that the TAB area be connected to copper area
directly under the TAB that is extended into the ground plane via multiple thermal vias. Alternately, but not
recommended, the TAB may be left floating (i.e. no direct electrical connection). The TAB must not be connected
to any potential other than ground.
10.4.2 WSON Mounting
The NGN (Pullback) 8-Lead WSON package requires specific mounting techniques which are detailed in
Application Note 1187: Leadless Leadframe Package (LLP) (SNOA401). Referring to the section PCB Design
Recommendations in AN-1187, it should be noted that the pad style which should be used with the WSON
package is the NSMD (non-solder mask defined) type.
The thermal dissipation of the WSON package is directly related to the printed circuit board construction and the
amount of additional copper area connected to the DAP.
The DAP (exposed pad) on the bottom of the WSON package is connected to the die substrate via a conductive
die attach adhesive, and to device pin 2 and pin 7. As such, it is strongly recommend that the DAP area be
connected copper area directly under the DAP that is extended into the ground plane via multiple thermal vias.
Alternately, but not recommended, the DAP area may be left floating (i.e. no direct electrical connection). The
DAP area must not be connected to any potential other than ground.
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Definition of Terms
Dropout Voltage The input-voltage differential at which the circuit ceases to regulate against further reduction in
input voltage. Measured when the output voltage has dropped 100 mV from the nominal value
obtained at (VOUT + 5 V) input, dropout voltage is dependent upon load current and junction
temperature.
Input-Output Differential The voltage difference between the unregulated input voltage and the regulated
output voltage for which the regulator will operate.
Input Voltage The DC voltage applied to the input terminals with respect to ground.
Line Regulation The change in output voltage for a change in the input voltage. The measurement is made
under conditions of low dissipation or by using pulse techniques such that the average chip
temperature is not significantly affected.
Load Regulation The change in output voltage for a change in load current at constant chip temperature.
Long Term Stability Output voltage stability under accelerated life-test conditions after 1000 hours with
maximum rated voltage and junction temperature.
Output Noise Voltage The rms AC voltage at the output, with constant load and no input ripple, measured over
a specified frequency range.
Quiescent Current That part of the positive input current that does not contribute to the positive load current.
The regulator ground lead current.
Ripple Rejection The ratio of the peak-to-peak input ripple voltage to the peak-to-peak output ripple voltage.
Temperature Stability of VOUT The percentage change in output voltage for a thermal variation from room
temperature to either temperature extreme.
11.2 Documentation Support
11.2.1 Related Documentation
• AN-1520: A Guide to Board Layout for Best Thermal Resistance for Exposed Packages (SNVA183)
• AN-1187: Leadless Leadframe Package (LLP) (SNOA401)
• AN-2020: Thermal Design By Insight, Not Hindsight (SNVA419)
11.3 Related Links
Table 1 below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 1. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
LM2941
Click here
Click here
Click here
Click here
Click here
LM2941C
Click here
Click here
Click here
Click here
Click here
11.4 Trademarks
All trademarks are the property of their respective owners.
11.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
18
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11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
www.ti.com
22-Nov-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
LM2941CS
NRND
DDPAK/
TO-263
KTT
5
45
Non-RoHS
& Green
Call TI
Level-3-235C-168 HR
0 to 125
LM2941CS
P+
LM2941CS/NOPB
ACTIVE
DDPAK/
TO-263
KTT
5
45
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
0 to 125
LM2941CS
P+
Samples
LM2941CSX/NOPB
ACTIVE
DDPAK/
TO-263
KTT
5
500
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
0 to 125
LM2941CS
P+
Samples
LM2941CT
NRND
TO-220
KC
5
45
Non-RoHS
& Green
Call TI
Level-1-NA-UNLIM
0 to 125
LM2941CT
P+
LM2941CT/LF03
ACTIVE
TO-220
NDH
5
45
RoHS & Green
SN
Level-1-NA-UNLIM
LM2941CT
P+
Samples
LM2941CT/LF04
ACTIVE
TO-220
NEB
5
45
RoHS & Green
SN
Level-1-NA-UNLIM
LM2941CT
P+
Samples
LM2941CT/NOPB
ACTIVE
TO-220
KC
5
45
RoHS & Green
SN
Level-1-NA-UNLIM
0 to 125
LM2941CT
P+
Samples
LM2941LD
NRND
WSON
NGN
8
1000
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-40 to 125
L2941LD
LM2941LD/NOPB
ACTIVE
WSON
NGN
8
1000
RoHS & Green
NIPDAU | SN
Level-3-260C-168 HR
-40 to 125
L2941LD
Samples
LM2941LDX/NOPB
ACTIVE
WSON
NGN
8
4500
RoHS & Green
NIPDAU | SN
Level-3-260C-168 HR
-40 to 125
L2941LD
Samples
LM2941S
NRND
DDPAK/
TO-263
KTT
5
45
Non-RoHS
& Green
Call TI
Level-3-235C-168 HR
-40 to 125
LM2941S
P+
LM2941S/NOPB
ACTIVE
DDPAK/
TO-263
KTT
5
45
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
-40 to 125
LM2941S
P+
LM2941SX
NRND
DDPAK/
TO-263
KTT
5
500
Non-RoHS
& Green
Call TI
Level-3-235C-168 HR
-40 to 125
LM2941S
P+
LM2941SX/NOPB
ACTIVE
DDPAK/
TO-263
KTT
5
500
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
-40 to 125
LM2941S
P+
LM2941T
NRND
TO-220
KC
5
45
Non-RoHS
& Green
Call TI
Level-1-NA-UNLIM
-40 to 125
LM2941T
P+
LM2941T/LF03
ACTIVE
TO-220
NDH
5
45
RoHS & Green
SN
Level-1-NA-UNLIM
LM2941T/NOPB
ACTIVE
TO-220
KC
5
45
RoHS & Green
SN
Level-1-NA-UNLIM
Addendum-Page 1
-40 to 125
Samples
Samples
LM2941T
P+
Samples
LM2941T
P+
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
22-Nov-2022
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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