LM431_05

LM431 Adjustable Precision Zener Shunt Regulator March 2005 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 n See AN-1112 for micro SMD considerations Connection Diagrams TO-92: Plastic Package SOT-23: 3-Lead Small Outline 01005528 01005501 Top View 4-Bump micro SMD Top View SO-8: 8-Pin Surface Mount 01005554 01005502 Top view Top View (bump side down) Note: *NC = Not internally connected. Must be electrically isolated from the rest of the circuit for the microSMD package. © 2005 National Semiconductor Corporation DS010055 www.national.com LM431 Ordering Information Package Typical Accuracy Order Number/Package Marking 0.5% TO-92 LM431CCZ/ LM431CCZ LM431CIZ/ LM431CIZ SO-8 LM431CCM/ 431CCM LM431CCMX/ 431CCM LM431CIM/ 431CIM LM431CIMX/ 431CIM SOT-23 LM431CCM3/ N1B 1% LM431BCZ/ LM431BCZ LM431BIZ/ LM431BIZ LM431BCM/ 431BCM 2% LM431ACZ/ LM431ACZ LM431AIZ/ LM431AIZ LM431ACM/ LM431ACM 0˚C to +70˚C Rails −40˚C to +85˚C Rails 0˚C to +70˚C Tape & Reel M08A Rails −40˚C to +85˚C Tape &Reel Rails 0˚C to +70˚C Tape & Reel MF03A Rails −40˚C to +85˚C Tape &Reel 250 Units Tape and Reel 3k Units Tape and Reel Z03A Temperature Range Transport Media NSC Drawing LM431BCMX/ LM431ACMX/ 431BCM LM431ACM LM431BIM/ 431BIM LM431BIMX/ 431BIM LM431AIM/ LM431AIM LM431AIMX/ LM431AIM LM431BCM3/ LM431ACM3/ N1D N1F LM431CCM3X/ LM431BCM3X/ LM431ACM3X/ N1B N1D N1F LM431CIM3 N1A LM431CIM3X N1A micro SMD – – LM431BIM3 N1C LM431AIM3 N1E LM431BIM3X LM431AIM3X N1C N1E LM431AIBP LM431AIBPX (Note 1) −40˚C to +85˚C BPA04AFB Note 1: The micro SMD package marking is a 1 digit manufacturing Date Code only micro SMD Top View Marking Example 01005556 www.national.com 2 LM431 Symbol and Functional Diagrams 01005599 01005555 DC Test Circuits 01005504 FIGURE 1. Test Circuit for VZ = VREF 01005505 Note: VZ = VREF (1 + R1/R2) + IREF • R1 FIGURE 2. Test Circuit for VZ > VREF 01005506 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 235˚C 260˚C (lead temp.) 37V −10 mA to +150 mA −40˚C to +85˚C 0˚C to +70˚C −65˚C to +150˚C Reference Voltage Reference Input Current Internal Power Dissipation (Notes 3, 4) TO-92 Package SO-8 Package SOT-23 Package micro SMD Package Operating Conditions Min Cathode Voltage Cathode Current VREF 1.0 mA −0.5V 10 mA 0.78W 0.81W 0.28W 0.30W 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 LM431C (Figure 1 ) 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) VZ = VREF, II = 10 mA, TA = Full Range (Figure 1 ) IZ = 10 mA (Figure 2 ) VZ from VREF to 10V VZ from 10V to 36V −1.4 −1.0 2.0 −2.7 −2.0 4.0 µA mV/V 8.0 17 mV 2.485 2.500 2.510 V 2.470 2.495 2.520 V Min 2.440 Typ 2.495 Max 2.550 Units V 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 *NO TARGET FOR fi* ) 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) 01005507 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: 5 www.national.com LM431 Equivalent Circuit 01005503 Typical Performance Characteristics Input Current vs VZ Thermal Information 01005529 01005530 Input Current vs VZ Dynamic Impedance vs Frequency 01005531 01005509 www.national.com 6 LM431 Typical Performance Characteristics Stability Boundary Conditions (Continued) 01005510 01005511 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 01005512 01005513 Typical Applications Shunt Regulator Single Supply Comparator with Temperature Compensated Threshold 01005514 01005515 7 www.national.com LM431 Typical Applications (Continued) Higher Current Shunt Regulator Series Regulator 01005518 01005516 Crow Bar Output Control of a Three Terminal Fixed Regulator 01005519 01005517 www.national.com 8 LM431 Typical Applications (Continued) Over Voltage/Under Voltage Protection Circuit 01005520 Voltage Monitor 01005521 9 www.national.com LM431 Typical Applications Delay Timer (Continued) Current Limiter or Current Source 01005523 01005522 Constant Current Sink 01005524 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 A1 (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. www.national.com 10 LM431 Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin SOIC NS Package Number M08A SOT-23 Molded Small Outline Transistor Package (M3) NS Package Number MF03A 11 www.national.com LM431 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) NS Package Number Z03A www.national.com 12 LM431 Adjustable Precision Zener Shunt Regulator 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 A1 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 = 0.777 X2 = 0.904 X3 = 0.850 NS Package Number BPA04AFB 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. For the most current product information visit us at www.national.com. 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. 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