LM4431 Micropower Shunt Voltage Reference n Tolerates capacitive loads n Fixed reverse breakdown voltage of 2.50V General Description Ideal for space critical applications, the LM4431 voltage reference is available in the sub-miniature (3 mm x 1.3 mm) SOT-23 surface-mount package. The LM4431’s advanced design eliminates the need for an external stabilizing capacitor while ensuring stability with any capacitive load, thus making the LM4431 easy to use. The operating current range is 100 µA to 15 mA. The LM4431 utilizes fuse and zener-zap reverse breakdown voltage trim during wafer sort to ensure that the parts have an accuracy of better than ± 2.0% at 25˚C. Bandgap reference temperature drift curvature correction and low dynamic impedance ensure stable reverse breakdown voltage accuracy over a wide range of operating temperatures and currents. Key Specifications n n n n n Output voltage tolerance 25˚C: ± 2.0% (max) Low output noise (10 Hz to 10 kHz): 35 µVrms (typ) Wide operating current range: 100 µA to 15 mA Commercial temperature range: 0˚C to +70˚C Low temperature coefficient: 30 ppm/˚C (typ) Applications n n n n n n n Features n Small package: SOT-23 n No output capacitor required Portable, Battery-Powered Equipment Data Acquisition Systems Instrumentation Process Control Energy Management Product Testing Power Supplies Connection Diagram SOT-23 DS011374-1 * This pin must be left floating or connected to pin 2. Top View Order Number LM4431M3-2.5 See NS Package Number M03B (JEDEC Registration TO-236AB) SOT-23 Package Marking Information Only three fields of marking are possible on the SOT-23’s small surface. The following table gives the meaning of the three fields. Part Marking S2E Field Definition First Field: S = Reference Second Field: 2 = 2.500V Voltage Option Third Field: E = Initial Reverse Breakdown Voltage Tolerance of ± 2.0% © 1998 National Semiconductor Corporation DS011374 www.national.com LM4431 Micropower Shunt Voltage Reference July 1998 Absolute Maximum Ratings (Note 1) ESD Susceptibility Human Body Model (Note 3) 2 kV Machine Model (Note 3) 200V See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” for other methods of soldering surface mount devices. If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Reverse Current Forward Current Power Dissipation (TA = 25˚C) (Note 2) M3 Package Storage Temperature Lead Temperature M3 Package Vapor phase (60 seconds) Infrared (15 seconds) 20 mA 10 mA Operating Ratings(Notes 1, 2) 306 mW −65˚C to +150˚C Temperature Range (Tmin ≤ TA ≤ Tmax) Reverse Current LM4431-2.5 +215˚C +220˚C 0˚C ≤ TA ≤ +70˚C 100 µA to 15 mA LM4431-2.5 Electrical Characteristics Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25˚C. Symbol Parameter Conditions Typical LM4431M3 Units (Note 4) Limits (Limit) (Note 5) VR Reverse Breakdown Voltage Reverse Breakdown VoltageTolerance IRMIN ∆VR/∆T 2.500 Minimum Operating Current Coefficient ± 30 ± 30 ± 30 Reverse Breakdown Voltage IRMIN ≤ IR ≤ 1 mA 0.4 Change with Operating Current Change 1 mA ≤ IR ≤ 15 mA ± 50 mV (max) 100 µA (max) µA ppm/˚C ppm/˚C ppm/˚C mV 1.0 mV (max) 1.2 mV (max) 8.0 mV (max) 25 mV (max) 2.5 mV IR = 1 mA, f = 120 Hz IAC = 0.1 IR 1.0 Ω Wideband Noise IR = 100 µA 35 µVrms Reverse Breakdown Voltage 10 Hz ≤ f ≤ 10 kHz t = 1000 hrs 120 ppm ZR Reverse Dynamic Impedance eN ∆VR V 45 IR = 10 mA IR = 1 mA IR = 100 µA Average Reverse Breakdown Voltage Temperature ∆VR/∆IR IR = 100 µA IR = 100 µA Long Term Stability T = 25˚C ± 0.1˚C IR = 100 µA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (junction to ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature is PDmax = (TJmax − TA)/θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4431, TJmax = 125˚C, and the typical thermal resistance (θJA), when board mounted, is 326˚C/W for the SOT-23 package. Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. Note 4: Typicals are at TJ = 25˚C and represent most likely parametric norm. Note 5: Limits are 100% production tested at 25˚C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQC) methods. The limits are used to calculate National’s AOQL. www.national.com 2 Typical Performance Characteristics Temperature Drift for Different Average Temperature Coefficient Output Impedance vs Frequency DS011374-3 DS011374-2 Reverse Characteristics and Minimum Operating Current Noise Voltage DS011374-5 DS011374-4 Start-Up Characteristics LM4431-2.5 RS = 30k DS011374-6 DS011374-7 3 www.national.com Functional Block Diagram DS011374-8 Applications Information flows through the load (IL) and the LM4431 (IQ). Since load current and supply voltage may vary, RS should be small enough to supply at least the minimum acceptable IQ to the LM4431 even when the supply voltage is at its minimum and the load current is at its maximum value. When the supply voltage is at its maximum and IL is at its minimum, RS should be large enough so that the current flowing through the LM4431 is less than 15 mA. RS is determined by the supply voltage, (VS), the load and operating current, (IL and IQ), and the LM4431’s reverse breakdown voltage, VR. The LM4431 is a micro-power curvature-corrected 2.5V bandgap shunt voltage reference. For space critical applications, the LM4431 is available in the sub-miniature SOT-23 surface-mount package. The LM4431 has been designed for stable operation without the need of an external capacitor connected between the “+” pin and the “−” pin. If, however, a bypass capacitor is used, the LM4431 remains stable. The operating current range is 100 µA to 15 mA. The LM4431’s SOT-23 package has a parasitic Schottky diode between pin 2 (−) and pin 3 (Die attach interface contact). Therefore, pin 3 of the SOT-23 package must be left floating or connected to pin 2. In a conventional shunt regulator application (Figure 1) , an external series resistor (RS) is connected between the supply voltage and the LM4431. RS determines the current that Typical Applications DS011374-9 FIGURE 1. Shunt Regulator www.national.com 4 Typical Applications (Continued) DS011374-10 FIGURE 2. Bounded amplifier reduces saturation-induced delays and can prevent succeeding stage damage. Nominal clamping voltage is ± 3.9V (LM4431’s reverse breakdown voltage +2 diode VF). DS011374-11 FIGURE 3. Protecting Op Amp input. The bounding voltage is ± 4V with the LM4431 (LM4431’s reverse breakdown voltage + 3 diode VF). 5 www.national.com Typical Applications (Continued) DS011374-12 FIGURE 4. Programmable Current Source DS011374-14 DS011374-13 FIGURE 5. Precision 1 µA to 1 mA Current Sources www.national.com 6 7 LM4431 Micropower Shunt Voltage Reference Physical Dimensions inches (millimeters) unless otherwise noted Plastic Surface Mount Package (M3) NS Package Number M03B (JEDEC Registration TO-236AB) LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component in any component of a life support 1. Life support devices or systems are devices or sysdevice or system whose failure to perform can be reatems which, (a) are intended for surgical implant into sonably expected to cause the failure of the life support the body, or (b) support or sustain life, and whose faildevice or system, or to affect its safety or effectiveness. ure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5620-6175 Fax: 81-3-5620-6179 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.