LM2941

LM2941/LM2941C 1A Low Dropout Adjustable Regulator November 7, 2007 LM2941/LM2941C 1A Low Dropout Adjustable Regulator General Description The LM2941 positive voltage regulator features the ability to source 1A of output current with a typical dropout voltage of 0.5V and a maximum of 1V over the entire temperature range. Furthermore, 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 and the load. Familiar regulator features such as short circuit and thermal overload protection are also provided. 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 882309 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 16-Lead Ceramic Dual-in-Line Package 16-Lead Ceramic Surface Mount Package 8-Lead LLP Surface Mount Package 882331 Top View Order Number LM2941J/883 LM2941J-QMLV, 5962-9166701QEA See NS Package Number J16A 882332 Top View Order Number LM2941WG/883 LM2941WG-QMLV, 5962-9166701QYA See NS Package Number WG16A 882333 Top View Ordering Number LM2941LD, LM2941LDX See NS Package Number LDC08A Note: Pin 2 & 7 are fused to center DAP © 2007 National Semiconductor Corporation 8823 www.national.com LM2941/LM2941C Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage (Survival Voltage, ≤ 100ms) LM2941T, LM2941S, LM2941LD 60V LM2941CT, LM2941CS 45V Internal Power Dissipation (Note 4) Internally Limited Maximum Junction Temperature 150°C Storage Temperature Range Lead Temperature (Soldering, 10 seconds) TO-220 (T) Package −65°C ≤ TJ ≤ +150°C TO-263 (S) Package ESD Rating (Note 2) 260°C ±2 kV Operating Ratings Maximum Input Voltage Temperature Range LM2941T LM2941CT LM2941S LM2941CS LM2941J LM2941WG LM2941LD 26V −40°C ≤ TJ ≤ 125°C −40°C ≤ TJ ≤ 125°C −55°C ≤ TJ ≤ 125°C −55°C ≤ TJ ≤ 125°C −40°C ≤ TJ ≤ 125°C 0°C ≤ TJ ≤ 125°C 0°C ≤ TJ ≤ 125°C 260°C Electrical Characteristics—LM2941T, LM2941S, LM2941J, LM2941WG, LM2941LD 5V ≤ VO ≤ 20V, VIN = VO + 5V, CO = 22μF, unless otherwise specified. Specifications in standard typeface apply for TJ = 25°C, while those in boldface type apply over the full Operating Temperature Range. LM2941J LM2941WG Limit (Notes 3, 5) 1.237/1.211 1.313/1.339 Line Regulation Load Regulation Output Impedance Quiescent Current VO + 2V ≤ VIN ≤ 26V, IO = 5mA 50mA ≤ IO ≤ 1A 100 mADC and 20 mArms fO = 120Hz VO + 2V ≤ VIN < 26V, IO = 5mA VIN = VO + 5V, IO = 1A RMS Output Noise, % of VOUT Ripple Rejection Long Term Stability Dropout Voltage Short Circuit Current Maximum Line Transient Maximum Operational Input Voltage Reverse Polarity DC Input RO = 100, VO ≥ −0.6V Voltage Reverse Polarity Transient T ≤ 100ms, RO = 100Ω Input Voltage ON/OFF Threshold Voltage ON ON/OFF Threshold Voltage OFF ON/OFF Threshold Current www.national.com Parameter Conditions Typ LM2941T LM2941S LM2941LD Limit (Note 6) 1.237/1.211 1.313/1.339 10/10 10/10 Units (Limits) Reference Voltage 5mA ≤ IO ≤ 1A (Note 7) 1.275 4 7 7 10 30 0.003 0.005 0.4 0.5 110 1.9 75 V(min) V(max) mV/V(max) mV/V(max) mΩ/V 10/10 10/10 15/20 45/60 15/20 45/60 mA(max) mA(max) % 10Hz–100kHz IO = 5mA fO = 120Hz, 1 Vrms, IL = 100mA IO = 1A IO = 100mA VIN Max = 26V (Note 8) VO Max 1V Above Nominal VO RO = 100, T ≤ 100ms 0.02/0.04 0.8/1.0 200/200 1.6/1.3 60/60 0.02/0.04 0.8/1.0 200/200 1.6 60/60 %/V(max) %/1000 Hr V(max) mV(max) A(min) V(min) 31 −30 −75 1.30 1.30 26/26 −15/−15 −50/−50 0.80/0.80 2.00/2.00 26/26 −15/−15 −50/−50 0.80/0.80 2.00/2.00 VDC V(min) V(min) V(max) V(min) μA(max) IO ≤ 1A IO ≤ 1A VON/OFF = 2.0V, IO ≤ 1A 50 100/300 100/300 2 LM2941/LM2941C Electrical Characteristics—LM2941CT, LM2941CS 5V ≤ VO ≤ 20V, VIN = VO + 5V, CO = 22μF, unless otherwise specified. Specifications in standard typeface apply for TJ = 25°C, while those in boldface type apply over the full Operating Temperature Range. Parameter Reference Voltage Line Regulation Load Regulation Output Impedance Quiescent Current Conditions 5mA ≤ IO ≤ 1A (Note 7) VO + 2V ≤ VIN ≤ 26V, IO = 5mA 50mA ≤ IO ≤ 1A 100 mADC and 20 mArms fO = 120Hz VO + 2V ≤ VIN < 26V, IO = 5mA VIN = VO + 5V, IO = 1A RMS Output Noise, % of VOUT Ripple Rejection Long Term Stability Dropout Voltage Short Circuit Current Maximum Line Transient Maximum Operational Input Voltage Reverse Polarity DC Input Voltage RO = 100Ω, VO ≥ −0.6V Reverse Polarity Transient Input Voltage ON/OFF Threshold Voltage ON ON/OFF Threshold Voltage OFF ON/OFF Threshold Current T ≤ 100ms, RO = 100Ω IO ≤ 1A IO ≤ 1A VON/OFF = 2.0V, IO ≤ 1A IO = 1A IO = 100mA VIN Max = 26V (Note 8) VO Max 1V Above Nominal VO RO = 100Ω, T ≤ 100ms 31 −30 −55 1.30 1.30 50 26 −15 −45 0.80 2.00 100 VDC V(min) V(min) V(max) V(min) μA(max) 10Hz–100kHz IO = 5mA fO = 120Hz, 1 Vrms, IL = 100mA 10 30 0.003 0.005 0.4 0.5 110 1.9 55 0.8/1.0 200/200 1.6 45 0.02 15 45/60 mA(max) mA(max) % %/V(max) %/1000 Hr V(max) mV(max) A(min) V(min) Typ 1.275 4 7 7 Limit (Note 6) 1.237/1.211 1.313/1.339 10 10 Units (Limits) V(min) V(max) mV/V(max) mV/V(max) mΩ/V Thermal Performance Thermal Resistance Junction-to-Case Thermal Resistance Junction-to-Ambient 5-Lead TO-220 5-Lead TO-263 5-Lead TO-220 5-Lead TO-263 8-Lead LLP (Note 4) 3 3 53 73 35 °C/W °C/W °C/W °C/W °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 1.5kΩ 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), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max) − TA)/θJA. 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 P.C. board copper area thermally connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJA is 37°C/W; and with 1.6 or more square inches of copper area, θJA is 32°C/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 22°C. The value θJA for the LLP 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 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. 3 www.national.com LM2941/LM2941C 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. Typical Performance Characteristics Dropout Voltage Dropout Voltage vs. Temperature 882311 882312 Output Voltage Quiescent Current vs. Temperature 882313 882314 Quiescent Current Quiescent Current 882315 882316 www.national.com 4 LM2941/LM2941C Line Transient Response Load Transient Response 882317 882318 Ripple Rejection Output Impedance 882319 882320 Low Voltage Behavior Low Voltage Behavior 882321 882322 5 www.national.com LM2941/LM2941C Output Capacitor ESR Output at Voltage Extremes 882323 882324 Output at Voltage Extremes Peak Output Current 882325 882326 Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-3) 882327 882328 www.national.com 6 LM2941/LM2941C 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. 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. 7 www.national.com LM2941/LM2941C * Required if regulator is located far from power supply filter. ** COUT must be at least 22μF 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 300μA of pull-up current when S1 is open. (Assume 2V at the ON/OFF pin.) www.national.com 8 LM2941/LM2941C Equivalent Schematic Diagram 882301 9 www.national.com LM2941/LM2941C Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM2941J/883 LM2941J-QMLV, 5962-9166701QEA NS Package Number J16A Order Number LM2941WG/883 LM2941WG-QMLV, 5962-9166701QYA NS Package Number WG16A www.national.com 10 LM2941/LM2941C 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: Products Amplifiers Audio Clock Conditioners Data Converters Displays Ethernet Interface LVDS Power Management Switching Regulators LDOs LED Lighting PowerWise Serial Digital Interface (SDI) Temperature Sensors Wireless (PLL/VCO) www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/displays www.national.com/ethernet www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/powerwise www.national.com/sdi www.national.com/tempsensors www.national.com/wireless WEBENCH Analog University App Notes Distributors Green Compliance Packaging Design Support www.national.com/webench www.national.com/AU www.national.com/appnotes www.national.com/contacts www.national.com/quality/green www.national.com/packaging www.national.com/quality www.national.com/refdesigns www.national.com/feedback Quality and Reliability Reference Designs Feedback THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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