Document
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
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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.
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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
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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 .