LM431 Adjustable Precision Zener Shunt Regulator General Description Features The LM431 is a 3-terminal adjustable shunt regulator with guaranteed temperature stability over the entire temperature range of operation. 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. Y Y Y Y Y Average temperature coefficient 50 ppm/ C Temperature compensated for operation over the full temperature range Programmable output voltage Fast turn-on response Low output noise Connection Diagrams TO-92: Plastic Package SO-8: 8-Pin Surface Mount SOT-23: 3-Lead Small Outline TL/H/10055 - 2 TL/H/10055-1 Top View Order Number LM431ACZ, LM431AIZ, LM431BCZ, LM431BIZ, LM431CCZ or LM431CIZ TL/H/10055 - 28 Top View Top View Order Number LM431ACM, LM431AIM, LM431BCM, LM431BIM, LM431CCM or LM431CIM Order Number LM431ACM3, LM431AIM3, LM431BCM3, LM431BIM3, LM431CCM3 or LM431CIM3 Ordering Information* Typical Accuracy Package 0.5% Temperature Range 1% 2% TO-92 LM431CCZ LM431CIZ LM431BCZ LM431BIZ LM431ACZ LM431AIZ 0 C to a 70 C b 40 C to a 85 C SO-8 LM431CCM LM431CIM LM431BCM LM431BIM LM431ACM LM431AIM 0 C to a 70 C b 40 C to a 85 C SOT-23 LM431CCM3 LM431CIM3 LM431BCM3 LM431BIM3 LM431ACM3 LM431AIM3 0 C to a 70 C b 40 C to a 85 C *See Table 1 for package marking for SOT-23. C1996 National Semiconductor Corporation TL/H/10055 RRD-B30M17/Printed in U. S. A. http://www.national.com LM431 Adjustable Precision Zener Shunt Regulator December 1996 Absolute Maximum Ratings Cathode Voltage 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) Reference Voltage Reference Input Current Operating Conditions Cathode Voltage Cathode Current b 65 C to a 150 C b 40 C to a 85 C 0 C to a 70 C Lead Temperature TO-92 Package/SO-8 Package/SOT-23 Package (Soldering, 10 sec.) 265 C Internal Power Dissipation (Notes 1, 2) TO-92 Package SO-8 Package SOT-23 Package 37V Continuous Cathode Current b 10 mA to a 150 mA b 0.5V 10 mA Max 37V 100 mA Min VREF 1.0 mA Note 1: TJ Max e 150 C. Note 2: Ratings appy 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, and the SOT-23 at 2.2 mW/ C. 0.78W 0.81W 0.28W LM431 Electrical Characteristics TA e 25 C unless otherwise specified Symbol VREF Parameter Reference Voltage Conditions Min Typ Max Units 2.440 2.495 2.550 V VZ e VREF, II e 10 mA LM431B (Figure 1) 2.470 2.495 2.520 V VZ e VREF, II e 10 mA LM431C (Figure 1) 2.485 2.500 2.510 V 8.0 17 mV VZ from VREF to 10V b 1.4 b 2.7 VZ from 10V to 36V b 1.0 b 2.0 VZ e VREF, II e 10 mA LM431A (Figure 1) VDEV Deviation of Reference Input Voltage Over Temperature (Note 3) VZ e VREF, II e 10 mA, TA e Full Range (Figure 1) DVREF DVZ Ratio of the Change in Reference Voltage to the Change in Cathode Voltage IZ e 10 mA (Figure 2) IREF Reference Input Current R1 e 10 kX, R2 e % , II e 10 mA (Figure 2) 2.0 4.0 mA *IREF Deviation of Reference Input Current over Temperature R1 e 10 kX, R2 e % , II e 10 mA, TA e Full Range (Figure 2) 0.4 1.2 mA IZ(MIN) Minimum Cathode Current for Regulation VZ e VREF (Figure 1) 0.4 1.0 mA IZ(OFF) Off-State Current VZ e 36V, VREF e 0V (Figure 3) 0.3 1.0 mA Dynamic Output Impedance (Note 4) VZ e VREF, LM431A, Frequency e 0 Hz (Figure 1) 0.75 X VZ e VREF, LM431B, LM431C Frequency e 0 Hz (Figure 1) 0.50 X rZ http://www.national.com 2 mV/V LM431 Electrical Characteristics TA e 25 C unless otherwise specified (Continued) Note 3: Deviation of reference input voltage, VDEV, is defined as the maximum variation of the reference input voltage over the full temperature range. TL/H/10055 - 7 The average temperature coefficient of the reference input voltage, *VREF, is defined as: g *VREF ppm e C V ( ( VMax b VMin VDEV g 106 106 VREF (at 25 C) REF (at 25 C) e T2 b T1 T2 b T1 Where: T2 b T1 e full temperature change. *VREF can be positive or negative depending on whether the slope is positive or negative. Example: VDEV e 8.0 mV, VREF e 2495 mV, T2 b T1 e 70 C, slope is positive. 2495 mV ( 10 8.0 mV *VREF e 6 70 C e a 46 ppm/ C Note 4: The dynamic output impedance, rZ, is defined as: rZ e DVZ DIZ 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: rZ e DVZ j DIZ r #1 Z 3 a R1 R2 J( http://www.national.com Equivalent Circuit TL/H/10055 - 3 DC Test Circuits TL/H/10055-4 TL/H/10055 - 5 FIGURE 1. Test Circuit for VZ e VREF Note: VZ e VREF (1 a R1/R2) a IREF # R1 FIGURE 2. Test Circuit for VZ l VREF TL/H/10055 - 6 FIGURE 3. Test Circuit for Off-State Current http://www.national.com 4 Typical Performance Characteristics Input Current vs VZ Thermal Information Input Current vs VZ TL/H/10055 - 8 Dynamic Impedance vs Frequency TL/H/10055 - 10 TL/H/10055 - 9 Note 1: The areas under the curves represent conditions that may cause the device to oscillate. For curves B, C, and D, R2 and V a were adjusted to establish the initial VZ and IZ conditions with CL e 0. V a and CL were then adjusted to determine the ranges of stability. Stability Boundary Conditions TL/H/10055 - 11 Test Circuit for Curve A Above Test Circuit for Curves B, C and D Above TL/H/10055 - 12 TL/H/10055 - 13 5 http://www.national.com Typical Applications Single Supply Comparator with Temperature Compensated Threshold Shunt Regulator TL/H/10055-14 VO & # R1 1a R2 JV REF TL/H/10055 - 15 Series Regulator Output Control of a Three Terminal Fixed Regulator TL/H/10055-16 VO & # 1a R1 R2 J VREF VO e #1 a R1 R2 JV TL/H/10055 - 17 REF VO MIN e VREF a 5V http://www.national.com 6 Typical Applications (Continued) Higher Current Shunt Regulator Crow Bar TL/H/10055 - 18 VO e # 1a TL/H/10055 - 19 J R1 VREF R2 VLIMIT & # 1a J R1 VREF R2 Over Voltage/Under Voltage Protection Circuit TL/H/10055 - 20 LOW LIMIT & VREF HIGH LIMIT & VREF # #1 J J 1a R1B R2B a R1A R2A a VBE Voltage Monitor TL/H/10055 - 21 LOW LIMIT & VREF HIGH LIMIT & VREF #1 #1 a a J R1A R2A J R1B R2B LED ON WHEN a LOW LIMIT k V k HIGH LIMIT 7 http://www.national.com Typical Applications (Continued) Delay Timer Current Limiter or Current Source TL/H/10055 - 23 VREF IO e RCL TL/H/10055 - 22 DELAY e R # C # fin Va (V a ) b VREF Constant Current Sink TL/H/10055 - 24 Recommended Solder Pads for SOT-23 Package TL/H/10055 - 27 TABLE 1. Package Marking for SOT-23 Order Number http://www.national.com Top Mark LM431ACM3 N1F LM431AIM3 N1E LM431BCM3 N1D LM431BIM3 N1C LM431CCM3 N1B LM431CIM3 N1A 8 Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM431ACM or LM431AIM NS Package Number M08A SOT-23 Molded Small Outline Transistor Package (M3) Order Number LM60BIM3 or LM60CIM3 NS Package Number MA03B 9 http://www.national.com LM431 Adjustable Precision Zener Shunt Regulator Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Order Number LM431ACZ or LM431AIZ NS Package Number Z03A 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: 1. 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