LM2941,LM2941C LM2941/LM2941C 1A Low Dropout Adjustable Regulator Literature Number: SNVS770E LM2941/LM2941C 1A Low Dropout Adjustable Regulator and the load. Familiar regulator features such as short circuit and thermal overload protection are also provided. General Description The LM2941 positive voltage regulator features the ability to source 1A of output current with a typical dropout voltage of 0.5V and a maximum of 1V over the entire temperature range. Furthermore, a quiescent current reduction circuit has been included which reduces the ground pin current when the differential between the input voltage and the output voltage exceeds approximately 3V. The quiescent current with 1A of output current and an input-output differential of 5V is therefore only 30mA. Higher quiescent currents only exist when the regulator is in the dropout mode (VIN - 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 Features LLP space saving package Output voltage adjustable from 5V to 20V Dropout voltage typically 0.5V @ IO = 1A Output current in excess of 1A 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 Connection Diagram and Ordering Information TO-220 Plastic Package TO-263 Surface-Mount Package 882302 Top View Order Number LM2941T or LM2941CT See NS Package Number TO5A 882308 Order Number LM2941S, LM2941SX or LM2941CS, LM2941CSX See NS Package Number TS5B 8-Lead LLP Surface Mount Package 882333 Top View Ordering Number LM2941LD, LM2941LDX See NS Package Number LDC08A (c) 2011 National Semiconductor Corporation 8823 www.national.com LM2941/LM2941C 1A Low Dropout Adjustable Regulator June 8, 2011 LM2941/LM2941C Absolute Maximum Ratings (Note 1) Operating Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Maximum Input Voltage Temperature Range -40C TJ 125C LM2941T Input Voltage (Survival Voltage, 100ms) LM2941T, LM2941S, LM2941LD 60V LM2941CT, LM2941CS 45V Internal Power Dissipation (Note 4) Internally Limited Maximum Junction Temperature 150C Storage Temperature Range 26V 0C TJ 125C LM2941CT -40C TJ 125C LM2941S 0C TJ 125C LM2941CS -40C TJ 125C LM2941LD -65C TJ +150C Soldering Temperature (Note 9) TO-220 (T), Wave TO-263 (S) LLP-8 (LD) ESD Rating (Note 2) 260C, 10s 235C, 30s 235C, 30s 2 kV Electrical Characteristics--LM2941T, LM2941S, LM2941LD 5V VO 20V, VIN = VO + 5V, CO = 22F, unless otherwise specified. Specifications in standard typeface apply for TJ = 25C, while those in boldface type apply over the full Operating Temperature Range. Parameter Reference Voltage Line Regulation Conditions Typ 5mA IO 1A (Note 7) 1.275 VO + 2V VIN 26V, IO = 5mA LM2941T LM2941S LM2941LD Limit Units (Limits) 1.237/1.211 V(min) 1.313/1.339 V(max) 4 10/10 mV/V(max) 10/10 mV/V(max) Load Regulation 50mA IO 1A 7 Output Impedance 100 mADC and 20 mArms fO = 120Hz 7 VO + 2V VIN < 26V, IO = 5mA 10 15/20 mA(max) VIN = VO + 5V, IO = 1A 30 45/60 mA(max) Quiescent Current RMS Output Noise, % of VOUT 10Hz-100kHz IO = 5mA 0.003 Ripple Rejection fO = 120Hz, 1 Vrms, IL = 100mA 0.005 Long Term Stability m/V % 0.02/0.04 0.4 %/V(max) %/1000 Hr IO = 1A 0.5 0.8/1.0 V(max) IO = 100mA 110 200/200 mV(max) Short Circuit Current VIN Max = 26V (Note 8) 1.9 1.6 A(min) Maximum Line Transient VO Max 1V Above Nominal VO 75 60/60 V(min) 31 26/26 VDC Dropout Voltage RO = 100, t 100ms Maximum Operational Input Voltage Reverse Polarity DC Input Voltage RO = 100, VO -0.6V -30 -15/-15 V(min) Reverse Polarity Transient Input Voltage t 100ms, RO = 100 -75 -50/-50 V(min) ON/OFF Threshold Voltage ON IO 1A 1.30 0.80/0.80 V(max) ON/OFF Threshold Voltage OFF IO 1A 1.30 2.00/2.00 V(min) ON/OFF Threshold Current VON/OFF = 2.0V, IO 1A 50 100/300 A(max) www.national.com 2 5V VO 20V, VIN = VO + 5V, CO = 22F, unless otherwise specified. Specifications in standard typeface apply for TJ = 25C, while those in boldface type apply over the full Operating Temperature Range. Parameter Conditions Typ Units (Limits) 1.237/1.211 V(min) 1.313/1.339 V(max) 4 10 mV/V(max) 50mA IO 1A 7 10 mV/V(max) 100 mADC and 20 mArms fO = 120Hz 7 VO + 2V VIN < 26V, IO = 5mA 10 15 mA(max) VIN = VO + 5V, IO = 1A 30 45/60 mA(max) Reference Voltage 5mA IO 1A (Note 7) Line Regulation VO + 2V VIN 26V, IO = 5mA Load Regulation Output Impedance Quiescent Current Limit (Note 6) 1.275 RMS Output Noise, % of VOUT 10Hz-100kHz IO = 5mA 0.003 Ripple Rejection fO = 120Hz, 1 Vrms, IL = 100mA 0.005 Long Term Stability m/V % 0.02 0.4 %/V(max) %/1000 Hr IO = 1A 0.5 0.8/1.0 V(max) IO = 100mA 110 200/200 mV(max) Short Circuit Current VIN Max = 26V (Note 8) 1.9 1.6 A(min) Maximum Line Transient VO Max 1V Above Nominal VO 55 45 V(min) 31 26 VDC Dropout Voltage RO = 100, T 100ms Maximum Operational Input Voltage Reverse Polarity DC Input Voltage RO = 100, VO -0.6V -30 -15 V(min) Reverse Polarity Transient Input Voltage T 100ms, RO = 100 -55 -45 V(min) ON/OFF Threshold Voltage ON IO 1A 1.30 0.80 V(max) ON/OFF Threshold Voltage OFF IO 1A 1.30 2.00 V(min) ON/OFF Threshold Current VON/OFF = 2.0V, IO 1A 50 100 A(max) Thermal Performance Thermal Resistance Junction-to-Case, JC Thermal Resistance Junction-to-Ambient, JA (Note 4) 5-Lead TO-220 3 C/W 5-Lead TO-263 3 C/W 8-Lead LLP 5.3 C/W 5-Lead TO-220 53 C/W 5-Lead TO-263 73 C/W 8-Lead LLP 35 C/W Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions for which the device is intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: The Human Body Model (HBM) is a 100 pF capacitor discharged through a 1.5k resistor into each pin. Test method is per JESD22-A114. Note 3: 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 4: The maximum power dissipation is a function of TJ(max), JA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max) - TA)/JA. If this dissipation is exceeded, the die temperature will rise above 150C and the LM2941 will go into thermal shutdown. If the TO-263 package is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 square inches of copper area, JA is 50C/W; with 1 square inch of copper area, JA is 37C/W; and with 1.6 or more square inches of copper area, JA is 32C/W. Thermal performance for the LLP package was obtained using a JESD51-7 board with six vias, using no airflow and an ambient temperature of 22C. The value JA for the LLP package 3 www.national.com LM2941/LM2941C Electrical Characteristics--LM2941CT, LM2941CS LM2941/LM2941C is specifically dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for the LLP package, refer to Application Note AN-1187. It is recommended that 6 vias be placed under the center pad to improve thermal performance. Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All limits are used to calculate Outgoing Quality Level, and are 100% production tested. Note 6: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. Note 7: The output voltage range is 5V to 20V and is determined by the two external resistors, R1 and R2. See Typical Application Circuit. Note 8: Output current capability will decrease with increasing temperature, but will not go below 1A at the maximum specified temperatures. Note 9: 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. Typical Performance Characteristics Dropout Voltage Dropout Voltage vs. Temperature 882312 882311 Output Voltage Quiescent Current vs. Temperature 882313 www.national.com 882314 4 LM2941/LM2941C Quiescent Current Quiescent Current 882315 882316 Line Transient Response Load Transient Response 882318 882317 Ripple Rejection Output Impedance 882319 882320 5 www.national.com LM2941/LM2941C Low Voltage Behavior Low Voltage Behavior 882321 882322 Output Capacitor ESR Output at Voltage Extremes 882324 882323 Output at Voltage Extremes Peak Output Current 882325 www.national.com 882326 6 LM2941/LM2941C Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-3) 882328 882327 Maximum Power Dissipation (TO-263) (Note 4) 882329 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 100mV from the nominal value obtained at (VOUT + 5V) input, dropout voltage is dependent upon load current and junction temperature. Input Voltage: The DC voltage applied to the input terminals with respect to ground. Input-Output Differential: The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate. 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 VO: The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme. 7 www.national.com LM2941/LM2941C The DAP (exposed pad) on the bottom of the LLP package is internally connected to device ground at pin 2 and pin 7. The DAP can be connected directly to ground, or the DAP may be left floating (i.e. no direct electrical connection). The DAP must not be connected to any potential other than ground. For the LM2941LD in the LDC08A 8-Lead LLP package, the junction-to-case thermal rating, JC, is 5.3 C/W, where the case is the bottom of the package at the center of the DAP. Application Hints LLP MOUNTING The LDC08A (Pullback) 8-Lead LLP package requires specific mounting techniques which are detailed in National Semiconductor Application Note # 1187. Referring to the section PCB Design Recommendations in AN-1187 (Page 5), it should be noted that the pad style which should be used with the LLP package is the NSMD (non-solder mask defined) type. www.national.com 8 LM2941/LM2941C Typical Applications 5V to 20V Adjustable Regulator 882303 Note: Using 1k for R1 will ensure that the input bias current error of 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 22F 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; see curve. 1A Switch 882306 *** To assure shutdown, select Resistor R3 to guarantee at least 300A of pull-up current when S1 is open. (Assume 2V at the ON/OFF pin.) 9 www.national.com LM2941/LM2941C Equivalent Schematic Diagram 882301 www.national.com 10 LM2941/LM2941C Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM2941T or LM2941CT NS Package Number T05A TO-263 5-Lead Plastic Surface Mount Package Order Number LM2941S, LM2941SX, LM2941CS or LM2941CSX NS Package Number TS5B 11 www.national.com LM2941/LM2941C 8-Lead LLP Surface Mount Package Order Number LM2941LD, LM2941LDX NS Package Number LDC08A www.national.com 12 LM2941/LM2941C Notes 13 www.national.com LM2941/LM2941C 1A Low Dropout Adjustable Regulator Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH(R) Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise(R) Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagicTM www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise(R) Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION ("NATIONAL") PRODUCTS. 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