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  • LM2941x 1-A Low Dropout Adjustable Regulator

    • SNVS770I June   1999  – January 2015 LM2941 , LM2941C

      PRODUCTION DATA.  

  • CONTENTS
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  • LM2941x 1-A Low Dropout Adjustable Regulator
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics: LM2941T, LM2941S, LM2941LD
    6. 6.6 Electrical Characteristics: LM2941CT, LM2941CS
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Short-Circuit Current Limit
      2. 7.3.2 Overvoltage Shutdown (OVSD)
      3. 7.3.3 Thermal Shutdown (TSD)
      4. 7.3.4 Thermal Overload Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With ON/OFF Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Output Capacitor
        2. 8.2.2.2 Setting the Output Voltage
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Power Dissipation
    4. 10.4 Thermal Considerations
      1. 10.4.1 TO-263 Mounting
      2. 10.4.2 WSON Mounting
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Definition of Terms
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. IMPORTANT NOTICE

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • NDH|5
  • NEB|5
  • KTT|5
  • KC|5
Thermal pad, mechanical data (Package|Pins)
  • KTT|5
    • PPTD277
Orderable Information
  • snvs770i_oa
  • snvs770i_pm
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DATA SHEET

LM2941x 1-A Low Dropout Adjustable Regulator

1 Features

  • 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

2 Applications

  • Industrial
  • Automotive

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).

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.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2941 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
LM2941C 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

typapp_snvs770.gif

4 Revision History

Changes from H Revision (December 2014) to I Revision

  • Changed update pin names to TI nomenclature Go

Changes from G Revision (April 2013) to H Revision

  • 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 InfoGo

Changes from F Revision (April 2013) to G Revision

  • Changed layout of National Data Sheet to TI formatGo

5 Pin Configuration and Functions

TO-220 (KC) Plastic Package
4 Pins
Top View
882302.png
TO-263 (KTT) Surface-Mount Package
4 Pins
882308.png
WSON (NGN)Surface Mount Package
8 Leads
Top View
882333.gif

Pin Functions

PIN TYPE DESCRIPTION
NAME KC KTT NGN
ADJ 1 1 8 I Sets output voltage
ON/OFF 2 2 1 I Enable/Disable control
GND 3 3 2, 7 — Ground
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.

6 Specifications

6.1 Absolute Maximum Ratings(1)(2)

MIN MAX UNIT
Input voltage (Survival Voltage, ≤ 100 ms) LM2941T, LM2941S, LM2941LD 60 V
LM2941CT, LM2941CS 45 V
Internal power dissipation (3) Internally Limited
Maximum junction temperature 150 °C
Soldering remperature(4) TO-220 (T), Wave, 10 s 260 °C
TO-263 (S), 30 s 235 °C
WSON-8 (LD), 30 s 235 °C
Storage temperature, Tstg −65 150 °C
(1) 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.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications.
(3) 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.
(4) 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

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

MIN MAX UNIT
Temperatures LM2941T −40 125 °C
LM2941CT 0 125
LM2941S −40 125
LM2941CS 0 125
LM2941LD −40 125

6.4 Thermal Information

THERMAL METRIC(1)(3) LM2941LD LM2941S, LM2941T UNIT
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 °C/W
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) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

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 TEST CONDITIONS MIN TYP MAX UNIT
Reference voltage 5 mA ≤ IOUT ≤ 1 A(1) 1.211 1.275 1.339 V
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 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 7 mΩ/V
Quiescent current VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA 10 20 mA
VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA, TJ = 25°C 10 15
VIN = VOUT + 5 V, IOUT = 1 A 30 60 mA
VIN = VOUT + 5 V, IOUT = 1 A, TJ = 25°C 30 45
RMS output noise, % of VOUT 10 Hz to 100 kHz, IOUT = 5 mA 0.003%
Ripple rejection ƒOUT = 120 Hz, 1 Vrms, IL = 100 mA 0.005 0.04 %/V
ƒOUT = 120 Hz, 1 Vrms, IL = 100 mA, TJ = 25°C 0.005 0.02
Long-term stability 0.4 %/1000 Hr
Dropout voltage IOUT = 1 A 0.5 1 V
IOUT = 1 A, TJ = 25°C 0.5 0.8
IOUT = 100 mA 110 200 mV
Short-circuit current VIN max = 26 V(2) 1.6 1.9 A
Maximum line transient VOUT max 1 V above nominal VOUT
ROUT = 100 Ω, t ≤ 100 ms		 60 75 V
Maximum operational input voltage 26 31 VDC
Reverse polarity
DC input voltage		 ROUT = 100 Ω, VOUT ≥ −0.6 V −15 −30 V
Reverse polarity
transient input voltage		 t ≤ 100 ms, ROUT = 100 Ω −50 −75
ON/OFF threshold
voltage ON		 IOUT ≤ 1 A 1.30 0.80 V
ON/OFF threshold
voltage OFF		 IOUT ≤ 1 A 2 1.3
ON/OFF threshold
current		 VON/OFF = 2 V, IOUT ≤ 1 A 50 300 μA
VON/OFF = 2 V, IOUT ≤ 1 A, TJ = 25°C 50 100
(1) The output voltage range is 5 V to 20 V and is determined by the two external resistors, R1 and R2. See Figure 18.
(2) Output current capability will decrease with increasing temperature, but will not go below 1 A at the maximum specified temperatures.

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 TEST CONDITIONS MIN TYP MAX UNIT
Reference voltage 5 mA ≤ IOUT ≤ 1 A(1) 1.211 1.275 1.339 V
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 mV/V
Load regulation 50 mA ≤ IOUT ≤ 1 A, TJ = 25°C 7 10 mV/V
Output impedance 100 mADC and 20 mArms, ƒOUT = 120 Hz 7 mΩ/V
Quiescent current VOUT + 2 V ≤ VIN < 26 V, IOUT = 5 mA, TJ = 25°C 10 15 mA
VIN = VOUT + 5 V, IOUT = 1 A 30 60 mA
VIN = VOUT + 5 V, IOUT = 1 A, TJ = 25°C 30 45
RMS output noise, % of VOUT 10 Hz to 100 kHz
IOUT = 5 mA		 0.003%
Ripple rejection ƒOUT = 120Hz, 1 Vrms, IL = 100 mA, TJ = 25°C 0.005 0.02 %/V
Long-term stability 0.4 %/1000 Hr
Dropout voltage IOUT = 1A 0.5 1 V
IOUT = 1A, TJ = 25°C 0.5 0.8
IOUT = 100 mA 110 200 mV
Short-circuit current VIN max = 26 V(2), TJ = 25°C 1.6 1.9 A
Maximum line transient VOUT max 1 V above nominal VOUT, ROUT = 100 Ω, t ≤ 100 ms, , TJ = 25°C 45 55 V
Maximum operational input voltage TJ = 25°C 26 31 VDC
Reverse polarity
DC input voltage		 ROUT = 100 Ω, VOUT ≥ −0.6 V, TJ = 25°C −15 −30 V
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 1.3 0.8 V
ON/OFF threshold
voltage OFF		 IOUT ≤ 1 A, TJ = 25°C 2 1.3
ON/OFF threshold
current		 VON/OFF = 2 V, IOUT ≤ 1 A, TJ = 25°C 50 100 μA
(1) The output voltage range is 5 V to 20 V and is determined by the two external resistors, R1 and R2. See Typical Application.
(2) Output current capability will decrease with increasing temperature, but will not go below 1 A at the maximum specified temperatures.

6.7 Typical Characteristics

882311.png
Figure 1. Dropout Voltage
882313.png
Figure 3. Output Voltage
882315.png
Figure 5. Quiescent Current
882317.png
Figure 7. Line Transient Response
882319.png
Figure 9. Ripple Rejection
882321.png
Figure 11. Low Voltage Behavior
882323.png
Figure 13. Output Capacitor ESR
882325.png
Figure 15. Output at Voltage Extremes
882327.png
Figure 17. Maximum Power Dissipation (TO-220)
882312.png
Figure 2. Dropout Voltage vs. Temperature
882314.png
Figure 4. Quiescent Current vs. Temperature
882316.png
Figure 6. Quiescent Current
882318.png
Figure 8. Load Transient Response
882320.png
Figure 10. Output Impedance
882322.png
Figure 12. Low Voltage Behavior
882324.png
Figure 14. Output at Voltage Extremes
882326.png
Figure 16. Peak Output Current

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

fbd1_snvs770.gif

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.

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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