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AT431
Low-Voltage Adjustable Precision Shunt Regulator Features
Low-Voltage Operation: Down to 1.24V 1% Reference-Voltage Tolerance Adjustable Output Voltage, Vo=Vref to 12V Low Operational Cathode Current....50A 0.25 Typical Output Impedance SOT-23-3 , SOT-23-5 and TO-92 Packages
Description
The AT431 is low-voltage three-terminal adjustable voltage reference with specified thermal stability over applicable commercial temperature ranges. Output voltage may be set to any value between Vref (1.24V) and 12V with two external resistors (see Figure 2). When used with an optocoupler, the AT431 is ideal voltage reference in isolated feedback circuits for 1.8V to 12 V switching-mode power supplies. This device has typical output impedance of 0.20. Active output circuitry provides a very sharp turn-on characteristic, making the AT431 excellent replacements for low-voltage zener diodes in many applications, including onboard regulation and adjustable power supplies.
Application
Linear Regulators Voltage Reference for Power Circuit
Block Diagram and Symbol
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 1
AT431
Low-Voltage Adjustable Precision Shunt Regulator Equivalent Schematic
Pin Assignments
Ordering Information Part number
AT431Z AT431X AT431UN AT431UT AT431C
Package
TO-92 SOT-25 SOT-23 SOT-23 SOT-89
Marking
Z X N T C
*
: Data Code
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 2
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Absolute maximum ratings (TA = 25oC)
Parameter Cathode voltage Continuous cathode current range Reference Current Operating temperature Storage temperature Package thermal impedance JA Symbol VKA IK IREF TOPR TSTG SOT-23-5 SOT-23-3 TO-92 PD Limits 12 -20~20 -0.05~3 -30~+85 -55~+150 347 156 (TJ(max)-TA)/ JA unit V mA mA o C o C o C/W
Power Dissipation
Stresses beyond those listed under " absolute maximum ratings" may cause permanent damage to the device. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Recommend operating condtion
Parameter Cathode voltage VKA Continuous cathode current range IK Operating free-air temperature range TA min Vref 0.05 0 Max 12 15 70 unit V mA o C
Electrical characteristics (unless otherwise noted)
Parameter Reference Voltage Symbol Vref (TA = 25oC) Vref (TA = full o range 0~70 C) Vref(dev) Vref / VKA Iref Iref(dev) IK(min) IK(off) | ZKA | Min. 1.228 1.221 Typ. 1.24 4 -1.5 0.15 0.05 40 0.001 0.20 Max. 1.252 1.259 20 -2.7 0.5 0.3 50 0.1 0.4 Unit V V mV Conditions VKA= Vref (Figure 1) IK=10mA
Vref deviation over full temperature range Ratio of Vref change in cathode voltage change Reference terminal current Iref deviation over full temperature range Minimum cathode current for regulation Off-state cathode current Dynamic impedance
VKA= Vref IK=10mA (Figure 1) mV/V VKA= Vref to 12V IK=10mA (Figure 2) A IK=10mA (Figure 2) R1=10K A IK=10mA R1=10K (Figure 2) R2=open A VKA= Vref (Figure 1) A VKA=12V Vref =0V (Figure 3) VKA= Vref f1KHz IK=0.1mA to 15mA
(Figure 1)
* The dynamic impedance is defined as : |ZKA| = VKA / IKA
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 3
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Parameter Measurement Information
Figure 1. Test Circuit for VKA=Vref VO= VKA=Vref
Figure 2. Test Circuit for VKA>Vref VO= VKA=Vref *(1+R1/R2)+Iref *R1
Figure 3. Test Circuit for IK(off)
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 4
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Figure 4.
Figure 5.
Figure 6.
Figure 7.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 5
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Figure 8.
Figure 9.
Figure 10.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 6
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Application Circuit
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 7
AT431
Low-Voltage Adjustable Precision Shunt Regulator
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 8
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Above shows the AT4311 used in a 3.3V isolated flyback supply. Output voltage Vo can be as low as reference voltage Vref (1.24V1%). The output of the regulator, plus the forward voltage drop of the optocoupler LED (1.24+1.4=2.64V), determine the minimum voltage that can be regulated in an isolated in an isolated supply configuration. Regulated voltage as low as 2.7V is possible using the circuit.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 9
AT431
Low-Voltage Adjustable Precision Shunt Regulator Package Information SOT-23
SYMBOL A A1 B C D E E H L S R
MILLIMETERS MIN MAX 0.787 1.194 0.025 0.127 0.356 0.559 0.086 0.152 2.667 3.048 1.194 1.397 1.778 2.032 2.083 2.489 0.102 0.305 0.432 0.559 8 0
INCHES MIN 0.031 0.001 0.014 0.0034 0.105 0.047 0.070 0.082 0.004 0.017 0 MAX 0.047 0.005 0.022 0.006 0.120 0.055 0.080 0.098 0.012 0.022 8
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 10
AT431
Low-Voltage Adjustable Precision Shunt Regulator SOT-25
SYMBOL A A1 A2 b C D E E1 L e E1 r
INCHES MIN 0.035 0.000 0.035 0.010 0.003 0.110 0.102 0.059 0.014 0.037ref 0.075ref 00 100 MAX 0.057 0.006 0.051 0.020 0.008 0.122 0.118 0.069 0.022
MILLIMETERS MIN MAX 0.90 1.45 0.00 0.15 0.90 1.30 0.25 0.50 0.08 0.20 2.80 3.10 2.60 3.00 1.50 1.75 0.35 0.55 0.95ref 1.90ref 00 100
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 11
AT431
Low-Voltage Adjustable Precision Shunt Regulator SOT-89
SYMBOL A B B b1 C C1 D D1 E H
MILLIMETERS MIN MAX 1.397 1.600 0.356 0.483 2.388 2.591 0.406 0.533 -4.242 0.787 1.194 4.394 4.597 1.397 1.753 1.448 1.549 0.381 0.432
INCHES MIN 0.055 0.014 0.094 0.016 -0.031 0.173 0.055 0.057 0.015 MAX 0.063 0.019 0.102 0.021 0.167 0.047 0.181 0.069 0.061 0.017
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 12
AT431
Low-Voltage Adjustable Precision Shunt Regulator TO-92
SYMBOL A B C D E e e1 L
MILLIMETERS MIN MAX 3.4 3.8 0.3 0.5 4.4 4.8 4.4 4.8 0.9 1.5 1.17 1.37 2.39 2.69 12 16
INCHES MIN 0.134 0.012 0.173 0.173 0.035 0.046 0.094 0.472 MAX 0.150 0.020 0.189 0.189 0.059 0.054 0.106 0.630
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 13
AT431
Low-Voltage Adjustable Precision Shunt Regulator
Reflow Condition (IR/Convection or VPR Reflow)
Reference JEDEC Standard J-STD-020A
Classification Reflow Profiles
Convection or IR/Convction Average Heating Rate(180C to peak) Preheat Temperature(12520C) Temperature maintained above 180C Time within 5C of actual Peak Temperature Peak Temperature Range(Note 1) Cooling Rate Time 25C to Peak Temperature 5C/second max. 120 seconds max. 10~150 seconds 10~20 seconds 219~225C or 235~240C 6C /second max. 6 minutes max. VPR 10C/second max.
60 seconds 219~225C or 235~240C 10C/second max.
*1 The maximum peak temperatures for IR and VP reflow are depending on package dimensions.
Package Reflow Conditions
Pkg. Thickness 2.5mm and Pkg. Thickness <2.5mm and all bags Pkg. Volume 350 mm3 Convection 219~225C VPR 219~225C IR/Convection 219~225C Pkg. Thickness <2.5mm and Pkg. Volume <350 mm3 Convection 235~240C VPR 235~240C IR/Convection 235~240C
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 14

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