SPX3940 1A Low Dropout Voltage Regulator February 2012 Rev. 1.0.0 GENERAL DESCRIPTION The SPX3940 is a 1A, accurate voltage regulator with a low drop out voltage of 280mV (typical) at 1A. These regulators are specifically designed for low voltage applications that require a low dropout voltage and a fast transient response. They are fully fault protected against overcurrent, reverse battery, and positive and negative voltage transients. The SPX3940 is offered in 3-pin SOT223 and TO-263 packages. For a 3A version, refer to the SPX29300 data sheet. APPLICATIONS Power Supplies LCD Monitors Portable Instrumentation Medical and Industrial Equipments FEATURES Guaranteed 1.5A Peak Current 1% Output Accuracy SPX3940A Low Quiescent Current Low Dropout Voltage of 280mV at 1A Extremely Tight Load and Line Regulation Extremely Fast Transient Response Reverse-battery Protection Internal Thermal Protection Internal Short Circuit Current Limit Replacement for LM3940 Standard SOT223 & TO-263 packages TYPICAL APPLICATION DIAGRAM Fig. 1: SPX3940 Application Diagram - Fixed Output Linear Regulator Exar Corporation 48720 Kato Road, Fremont CA 94538, USA www.exar.com Tel. +1 510 668-7000 - Fax. +1 510 668-7001 SPX3940 1A Low Dropout Voltage Regulator ABSOLUTE MAXIMUM RATINGS OPERATING RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. Input Voltage VIN .................................................... 16V Junction Temperature Range ....................-40C to 125C Packages Thermal Resistance SOT-223 Junction to Case (at TA) ..................... 15C/W SOT-223 Junction to Ambient ........................62.3C/W TO-263 Junction to Case (at TA) ......................... 3C/W TO-263 Junction to Ambient ..........................31.4C/W Input Voltage VIN ................................................... 20V1 Storage Temperature .............................. -65C to 150C Lead Temperature (Soldering, 5 sec) ..................... 260C Note 1: Maximum positive supply voltage of 20V must be of limited duration (<100ms) and duty cycle (<1%). The maximum continuous supply voltage is 16V. ELECTRICAL SPECIFICATIONS Specifications with standard type are for an Operating Ambient Temperature of TA = 25C only; limits applying over the full Operating Junction Temperature range are denoted by a "*". Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T A = 25C, and are provided for reference purposes only. Unless otherwise indicated, V IN = VIN +1V, IOUT = 10mA, CIN = 6.8F, COUT = 10F, TA = 25C. Parameter Min. Typ. Max. Units Conditions 1.782 1.755 1.764 1.737 1.8 1.8 1.8 1.8 1.818 1.845 1.836 1.863 2.475 2.437 2.450 2.412 2.5 2.5 2.5 2.5 2.525 2.563 2.550 2.588 3.267 3.217 3.234 3.184 3.3 3.3 3.3 3.3 3.333 3.383 3.366 3.416 4.950 4.875 4.900 4.825 5.0 5.0 5.0 5.0 5.050 5.125 5.100 5.175 Line Regulation 0.2 1.0 % IOUT=10mA, (VOUT +1V)VIN16V Load Regulation 0.3 1.5 % VIN = VOUT +1V,10mAIOUT1A 20 100 ppm/C * 1.8V version Output Voltage - SPX3940A (1%) Output Voltage - SPX3940 (2%) V V * IOUT=10mA 10mAIOUT1A, 6VVIN16V * 2.5V version Output Voltage - SPX3940A (1%) Output Voltage - SPX3940 (2%) V V * IOUT=10mA 10mAIOUT1A, 6VVIN16V * 3.3V version Output Voltage - SPX3940A (1%) Output Voltage - SPX3940 (2%) V V * IOUT=10mA 10mAIOUT1A, 6VVIN16V * 5.0V version Output Voltage - SPX3940A (1%) Output Voltage - SPX3940 (2%) V V * IOUT=10mA 10mAIOUT1A, 6VVIN16V * All Voltage Options - Output Voltage temperature Coefficient Dropout Voltage2 (except 1.8V version) Ground Current3 IGNDDO Ground Pin Current at Dropout Current Limit Output Noise Voltage (c) 2012 Exar Corporation 1.5 70 200 mV * IOUT=100mA 280 550 mV * IOUT=1A 12 25 mA * IOUT=750mA, VIN = VOUT +1V 18 mA IOUT=1A 1.2 mA VIN = 0.1V less than specified V OUT IOUT=10mA, 2.2 A 400 VRMS 10Hz-100KHz, IL=100mA, CL=10F 260 VRMS 10Hz-100KHz, IL=100mA, CL=33F 2/11 VOUT = 0V4 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator Note 2: Dropout voltage is defined as the input to output differential when the output voltage drops to 99% of its normal value. Note 3: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current to the ground current. Note 4: VIN=VOUT(NOMINAL)+1V. For example, use V IN=4.3V for a 3.3V regulator. Employ pulse-testing procedures to minimize temperature rise. BLOCK DIAGRAM Fig. 2: SPX3940 Block Diagram PIN ASSIGNMENT Fig. 3: SPX3940 Pin Assignment (c) 2012 Exar Corporation 3/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator ORDERING INFORMATION Part Number SPX3940AM3-L-1-8 SPX3940AM3-L-1-8/TR SPX3940AM3-L-2-5 SPX3940AM3-L-2-5/TR SPX3940AM3-L-3-3 SPX3940AM3-L-3-3/TR SPX3940AM3-L-5-0 SPX3940AM3-L-5-0/TR SPX3940AT-L-1-8 SPX3940AT-L-1-8/TR SPX3940AT-L-3-3 SPX3940AT-L-3-3/TR SPX3940AT-L-5-0 SPX3940AT-L-5-0/TR SPX3940M3-L-2-5 SPX3940M3-L-2-5/TR SPX3940M3-L-3-3 SPX3940M3-L-3-3/TR SPX3940M3-L-5-0 SPX3940M3-L-5-0/TR SPX3940T-L-3-3 SPX3940T-L-3-3/TR SPX3940T-L-5-0 SPX3940T-L-5-0/TR Temperature Range -40CTJ+125C -40CTJ+125C -40CTJ+125C -40CTJ+125C Marking 3940A 18YYWWL XXX 3940A 25YYWWL XXX 3940A 33YYWWL XXX 3940A 50YYWWL XXX Packing Quantity Package 3-pin SOT-223 3-pin SOT-223 3-pin SOT-223 3-pin SOT-223 Note 1 2.5K/Tape & Reel Bulk Lead Free 1.8V Output Voltage - 1% Lead Free 2.5V Output Voltage - 1% Lead Free 3.3V Output Voltage - 1% Lead Free 5.0V Output Voltage - 1% Lead Free 1.8V Output Voltage - 1% Lead Free 3.3V Output Voltage - 1% Lead Free 5.0V Output Voltage - 1% Lead Free 2.5V Output Voltage - 2% Lead Free 3.3V Output Voltage - 2% Lead Free 5.0V Output Voltage - 2% Lead Free 3.3V Output Voltage - 2% Lead Free 5.0V Output Voltage - 2% 2.5K/Tape & Reel Bulk 2.5K/Tape & Reel Bulk 2.5K/Tape & Reel Bulk -40CTJ+125C SPX3940AT 18YYWWLX 3-pin TO-263 500/Tape & Reel -40CTJ+125C SPX3940AT 33YYWWLX 3-pin TO-263 500/Tape & Reel -40CTJ+125C SPX3940AT 50YYWWLX 3-pin TO-263 500/Tape & Reel -40CTJ+125C 3940M3 25YYWWL 3-pin SOT-223 2.5K/Tape & Reel -40CTJ+125C 3940M3 33YYWWL 3-pin SOT-223 2.5K/Tape & Reel -40CTJ+125C 3940M3 50YYWWL 3-pin SOT-223 2.5K/Tape & Reel -40CTJ+125C SPX3940T 33YYWWLX 3-pin TO-263 500/Tape & Reel -40CTJ+125C SPX3940T 33YYWWLX 3-pin TO-263 500/Tape & Reel Bulk Bulk Bulk Bulk Bulk Bulk Bulk Bulk Note 2 "YY" = Year - "WW" = Work Week - "X" = Lot Number - when applicable. (c) 2012 Exar Corporation 4/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator TYPICAL PERFORMANCE CHARACTERISTICS Schematic and BOM from Application Information section of this datasheet. Fig. 4: Line Regulation Fig. 5: Load Regulation Fig. 6: Ground Current vs Load Current Fig. 7: Ground Current vs Input Voltage Fig. 8: Ground Current vs Load Current in Dropout Fig. 9: Dropout Voltage vs Load Current (c) 2012 Exar Corporation 5/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator Fig. 10: Ground Current vs Temperature ILOAD=100mA Fig. 11: Output Voltage vs Temperature ILOAD=100mA Fig. 12: Ground Current vs Temperature ILOAD=500mA Fig. 13: Ground Current vs Temperature Dropout, ILOAD=750mA Fig. 14: Ground Current vs Temperature ILOAD=1.5A Fig. 15: Ground Current vs Temperature Dropout, ILOAD=1.5A (c) 2012 Exar Corporation 6/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator Fig. 16: Dropout Voltage vs Temperature ILOAD=750mA Fig. 17: Dropout Voltage vs Temperature ILOAD=1.5A Fig. 18: Enable Current vs Temperature VEN=16V Fig. 19: Enable Threshold vs Temperature (c) 2012 Exar Corporation 7/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator THEORY OF OPERATION TJ = TA + PD * (HA + CH + JC) or The SPX3940 incorporates protection against over-current faults, reversed load insertion, over temperature operation, and positive and negative transient voltage. TJ = 50 + 7.5 * (1 + 2 + 3) = 95C THERMAL CONSIDERATIONS The output capacitor is needed to insure stability and minimize the output noise. The value of the capacitor varies with the load. However, a minimum value of 10F aluminum capacitor will guarantee stability over all load conditions. A tantalum capacitor is recommended if a faster load transient response is needed. Reliable operation is insured. CAPACITOR REQUIREMENTS Although the SPX3940 offers limiting circuitry for overload conditions, it is still necessary to insure that the maximum junction temperature is not exceeded in the application. Heat will flow through the lowest resistance path, the junction-to-case path. In order to insure the best thermal flow of the component, proper mount-ing is required. Consult heatsink manufacturer for thermal resistance and design of heatsink. If the power source has a high AC impedance, a 0.1F ceramic capacitor between input & ground is recommended. MINIMUM LOAD CURRENT TO-220 Design Example: To ensure a proper behavior of the regulator under light load, a minimum load of 5mA for SPX3940 is required. Assume that VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 50C/W, HA= 1C/W, CH = 2C/W, and JC = 3C/W. Where TA = ambient temperature HA = heatsink to ambient thermal resistance CH = case to heatsink thermal resistance JC = junction to case thermal resistance The power calculated under these conditions is: Fig. 20: Fixed Output Linear Regulator PD = (VIN - VOUT) * IOUT = 7.5W. And the junction temperature is calculated as (c) 2012 Exar Corporation 8/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator PACKAGE SPECIFICATION 3-PIN SOT-223 (c) 2012 Exar Corporation 9/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator 3-PIN TO-263 (c) 2012 Exar Corporation 10/11 Rev. 1.0.0 SPX3940 1A Low Dropout Voltage Regulator REVISION HISTORY Revision Date A 04/14/2006 1.0.0 02/29/2012 Description Reformat of Datasheet Package drawing corrections FOR FURTHER ASSISTANCE Email: customersupport@exar.com Exar Technical Documentation: http://www.exar.com/TechDoc/default.aspx? EXAR CORPORATION HEADQUARTERS AND SALES OFFICES 48720 Kato Road Fremont, CA 94538 - USA Tel.: +1 (510) 668-7000 Fax: +1 (510) 668-7030 www.exar.com NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked; no responsibility, however , is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. or its in all Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. (c) 2012 Exar Corporation 11/11 Rev. 1.0.0