Description
LM431 Adjustable Precision Zener Shunt Regulator December 1999 LM431 Adjustable Precision Zener Shunt Regulator General Description The LM431 is a 3-terminal adjustable shunt regulator with guaranteed temperature stability over the entire temperature range of operation. It is now available in a chip sized package (4-Bump micro SMD) using National’s micro SMD package technology. The output voltage may be set at any level greater than 2.5V (VREF) up to 36V merely by selecting two external resistors that act as a voltage divided network. Due to the sharp turn-on characteristics this device is an excellent replacement for many zener diode applications. Features n Average temperature coefficient 50 ppm/˚C n Temperature compensated for operation over the full temperature range n Programmable output voltage n Fast turn-on response n Low output noise n LM431 in micro SMD package Connection Diagrams TO-92: Plastic Package SOT-23: 3-Lead Small Outline DS010055-28 DS010055-1 Top View 4-Bump micro SMD Top View SO-8: 8-Pin Surface Mount DS010055-54 DS010055-2 Top view Top View (bump side down) © 1999 National Semiconductor Corporation DS010055 www.national.com LM431 Ordering Information Package TO-92 Typical Accuracy Order Number/Package Marking 0.5% LM431CCZ/ LM431CCZ LM431CIZ/ LM431CIZ SO-8 LM431CCM/ 431CCM LM431CIM/ 431CIM SOT-23 LM431CCM3/ N1B LM431CIM3 N1A micro SMD – 1% LM431BCZ/ LM431BCZ LM431BIZ/ LM431BIZ LM431BCM/ 431BCM LM431BIM/ 431BIM LM431BCM3/ N1D LM431BIM3 N1C – 2% LM431ACZ/ LM431ACZ LM431AIZ/ LM431AIZ LM431ACM/ LM431ACM LM431AIM/ LM431AIM LM431ACM3/ N1F LM431AIM3 N1E LM431AIBP LM431AIBPX(Note 1) Temperature Range 0˚C to +70˚C Rails −40˚C to +85˚C 0˚C to +70˚C Rails and Tape &Reel −40˚C to +85˚C 0˚C to +70˚C Rails and Tape &Reel −40˚C to +85˚C −40˚C to +85˚C 250 Units Tape and Reel BPA04AFA 3k Units Tape and Reel MA03B M08A Z03A Transport Media NSC Drawing Note 1: The micro SMD package marking is a 2 digit manufacturing Date Code only micro SMD Top View Marking Example DS010055-56 The LM431 micro SMD Package will be marked with a two digit date manufacturing code. The underline indicates the bottom of the marking. Pin one will be placed at the bottom left hand corner, and the rest of the pin numbers will follow counter-clockwise. www.national.com 2 LM431 Symbol and Functional Diagrams DS010055-99 DS010055-55 DC Test Circuits DS010055-4 DS010055-5 FIGURE 1. Test Circuit for VZ = VREF Note: VZ = VREF (1 + R1/R2) + IREF • R1 FIGURE 2. Test Circuit for VZ > VREF DS010055-6 FIGURE 3. Test Circuit for Off-State Current 3 www.national.com LM431 Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range Operating Temperature Range Industrial (LM431xI) Commercial (LM431xC) Soldering Information Infrared or Convection (20 sec.) Wave Soldering (10 sec.) Cathode Voltage Continuous Cathode Current −65˚C to +150˚C −40˚C to +85˚C 0˚C to +70˚C 235˚C 260˚C (lead temp.) 37V −10 mA to +150 mA Reference Voltage Reference Input Current Internal Power Dissipation (Notes 3, 4) TO-92 Package SO-8 Package SOT-23 Package micro SMD Package −0.5V 10 mA 0.78W 0.81W 0.28W 0.30W Operating Conditions Cathode Voltage Cathode Current Min VREF 1.0 mA Max 37V 100 mA LM431 Electrical Characteristics TA = 25˚C unless otherwise specified Symbol VREF Parameter Reference Voltage Conditions VZ = VREF, II = 10 mA LM431A (Figure 1 ) VZ = VREF, II = 10 mA LM431B (Figure 1 ) VZ = VREF, II = 10 mA VDEV Deviation of Reference Input Voltage Over Temperature (Note 5) Ratio of the Change in Reference Voltage to the Change in Cathode Voltage IREF ∝IREF Reference Input Current Deviation of Reference Input Current over Temperature IZ(MIN) IZ(OFF) rZ Minimum Cathode Current for Regulation Off-State Current Dynamic Output Impedance (Note 6) LM431C (Figure 1 ) VZ = VREF, II = 10 mA, TA = Full Range (Figure 1 ) IZ = 10 mA VZ from VREF to 10V Min 2.440 2.470 2.485 Typ 2.495 2.495 2.500 8.0 −1.4 −1.0 2.0 Max 2.550 2.520 2.510 17 −2.7 −2.0 4.0 µA Units V V V mV mV/V (Figure 2 ) VZ from 10V to 36V R1 = 10 kΩ, R2 = ∞, II = 10 mA (Figure 2 ) R1 = 10 kΩ, R2 = ∞, II = 10 mA, TA = Full Range (Figure 2 ) VZ = VREF (Figure 1 ) VZ = 36V, VREF = 0V (Figure 3 ) VZ = VREF, LM431A, Frequency = 0 Hz (Figure 1 ) VZ = VREF, LM431B, LM431C Frequency = 0 Hz (Figure 1 ) 0.4 0.4 0.3 1.2 1.0 1.0 0.75 0.50 µA mA µA Ω Ω Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 3: TJ Max = 150˚C. Note 4: Ratings apply to ambient temperature at 25˚C. Above this temperature, derate the TO-92 at 6.2 mW/˚C, the SO-8 at 6.5 mW/˚C, the SOT-23 at 2.2 mW/˚C and the micro SMD at 3mW/˚C. Note 5: Deviation of reference input voltage, VDEV, is defined as the maximum variation of the reference input voltage over the full temperature range. www.national.com 4 LM431 LM431 Electrical Characteristics (Continued) DS010055-7 The average temperature coefficient of the reference input voltage, ∝VREF, is defined as: Where: T2 − T1 = full temperature change (0-70˚C). ∝VREF can be positive or negative depending on whether the slope is positive or negative. Example: VDEV = 8.0 mV, VREF = 2495 mV, T2 − T1 = 70˚C, slope is positive. Note 6: The dynamic output impedance, rZ, is defined as: When the device is programmed with two external resistors, R1 and R2, (see Figure 2 ), the dynamic output impedance of the overall circuit, rZ, is defined as: Equivalent Circuit DS010055-3 5 www.national.com LM431 Typical Performance Characteristics Input Current vs VZ Thermal Information Input Current vs VZ DS010055-29 DS010055-30 DS010055-31 Dynamic Impedance vs Frequency DS010055-10 DS010055-9 Stability Boundary Conditions DS010055-11 Note: The areas under the curves represent conditions that may cause the device to oscillate. For curves B, C, and D, R2 and V+ were adjusted to establish the initial VZ and IZ conditions with CL = 0. V+ and CL were then adjusted to determine the ranges of stability. Test Circuit for Curve A Above Test Circuit for Curves B, C and D Above DS010055-12 DS010055-13 www.national.com 6 LM431 Typical Applications Shunt Regulator Single Supply Comparator with Temperature Compensated Threshold DS010055-14 DS010055-15 Series Regulator Output Control of a Three Terminal Fixed Regulator DS010055-16 DS010055-17 Higher Current Shunt Regulator Crow Bar DS010055-18 DS010055-19 7 www.national.com LM431 Typical Applications (Continued) Over Voltage/Under Voltage Protection Circuit DS010055-20 Voltage Monitor DS010055-21 www.national.com 8 LM431 Typical Applications (Continued) Current Limiter or Current Source Delay Timer DS010055-23 DS010055-22 Constant Current Sink DS010055-24 Application Info 1.0 Mounting To ensure that the geometry of the micro SMD package maintains good physical contact with the printed circuit board, pin 1 (NC) must be soldered to the pcb. Please see AN-1112 for more detailed information regarding board mounting techniques for the micro SMD package. 2.0 LM431 micro SMD Light Sensitivity When the LM431 micro SMD package is exposed to bright sunlight, normal office fluorescent light, and other LED’s and lasers, it operates within the guaranteed limits specified in the electrical characteristics table. 9 www.national.com LM431 Physical Dimensions inches (millimeters) unless otherwise noted NS Package Number M08A SOT-23 Molded Small Outline Transistor Package (M3) NS Package Number MA03B www.national.com 10 LM431 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) NS Package Number Z03A 11 www.national.com LM431 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) NOTES: UNLESS OTHERWISE SPECIFIED 1. EPOXY COATING 2. 63Sn/37Pb EUTECTIC BUMP 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED. 5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT. 6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BA. 4-Bump micro SMD X1 = 0.780 X2 = 0.900 X3 = 0.700 NS Package Number BPA04AFA www.national.com 12 LM431 Adjustable Precision Zener Shunt Regulator Notes 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 AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure 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: support@nsc.com www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: europe.support@nsc.com 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 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: sea.support@nsc.com National Semiconductor J

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