LM2941T/NOPB

Product Folder Sample & Buy Support & Community Tools & Software Technical Documents 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 3 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback UNIT °C Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 5 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 7 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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) Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 9 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 11 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 13 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 Layout Example (continued) IN OUT GND ADJ ON/OFF GND GND COUT CIN R2 R1 Figure 22. LM2941 TO-220 Package Typical Layout Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 15 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 17 LM2941, LM2941C SNVS770I – JUNE 1999 – REVISED JANUARY 2015 www.ti.com 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 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C LM2941, LM2941C www.ti.com SNVS770I – JUNE 1999 – REVISED JANUARY 2015 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. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: LM2941 LM2941C 19 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