AT431 ETC1 | Alldatasheet
Document overview
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Technical content
Features
˙Low-V oltage Operation: Down to 1.24V ˙1% Reference-V oltage Tolerance ˙Adjustable Output V oltage, V o=Vref to 12V ˙Low Operational Cathode Current….50 μA ˙0.25Ω Typical Output Impedance ˙SOT-23-3 , SOT-23-5 and TO-92 Packages Application ˙Linear Regulators ˙Voltage Reference for Power Circuit
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 V ref (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 Ω. 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. Block Diagram and Symbol
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Equivalent Schematic Pin Assignments
Ordering Information
Part number Package Marking AT431Z TO-92 Z AT431X SOT-25 X AT431UN SOT-23 N AT431UT SOT-23 T AT431C SOT-89 C * : Data Code
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Absolute maximum ratings (TA = 25oC) Parameter Symbol Limits unit Cathode voltage VKA 12 V Continuous cathode current range IK -20~20 mA Reference Current IREF -0.05~3 mA Operating temperature T OPR -30~+85 oC Storage temperature T STG -55~+150 oC SOT-23-5 SOT-23-3 347Package thermal impedance θJA TO-92 156 oC / W Power Dissipation PD (TJ(max)-TA)/ θJA 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 min Max unit Cathode voltage VKA Vref 12 V Continuous cathode current range IK 0.05 15 mA Operating free-air temperature range TA 07 0 oC Electrical characteristics (unless otherwise noted) Parameter Symbol Min. Typ. Max. Unit Conditions Vref (TA = 25oC) 1.228 1.24 1.252 VReference V oltage Vref (TA = full range 0~70 oC) 1.221 - 1.259 V VKA= Vref IK=10mA (Figure 1) Vref deviation over full temperature range Vref(dev) -4 2 0 m V V KA= Vref IK=10mA (Figure 1) Ratio of Vref change in cathode voltage change ∆ Vref /∆ VKA - -1.5 -2.7 mV/V V KA= Vref to 12V IK=10mA (Figure 2) Reference terminal current Iref - 0.15 0.5 µA IK=10mA R1=10KΩ (Figure 2) Iref deviation over full temperature range Iref(dev) - 0.05 0.3 µAI K=10mA R1=10K Ω R2=open (Figure 2) Minimum cathode current for regulation IK(min) -4 0 5 0 µA VKA= Vref (Figure 1) Off-state cathode current IK(off) -0 . 0 0 1 0 . 1 µA VKA=12V Vref =0V (Figure 3) Dynamic impedance | ZKA | - 0.20 0.4 Ω VKA= Vref f ≤1KHz IK=0.1mA to 15mA (Figure 1) * The dynamic impedance is defined as : |ZKA| = ∆ VKA /∆ IKA
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw F i g u r e 4 . F i g u r e 5 . F i g u r e 6 . F i g u r e 7 .
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw F i g u r e 8 . F i g u r e 9 . Figure 10.
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Application Circuit
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Above shows the AT4311 used in a 3.3V isolated flyback supply. Output voltage Vo can be as low as reference voltage Vref (1.24V±1%). The output of the regulator, plus the forward voltage drop of the optocoupler LED (1.24+1.4= 2.64V), determine the minimum vol tage that can be regulated in an isolated in an isolated supply configuration. Regulated vo ltage as low as 2.7V is possible using the circuit.
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw
Package Information
A 0.787 1.194 0.031 0.047 A1 0.025 0.127 0.001 0.005 B 0.356 0.559 0.014 0.022 C 0.086 0.152 0.0034 0.006 D 2.667 3.048 0.105 0.120 E 1.194 1.397 0.047 0.055 E 1.778 2.032 0.070 0.080 H 2.083 2.489 0.082 0.098 L 0.102 0.305 0.004 0.012 S 0.432 0.559 0.017 0.022 R 0。 8。 0。 8。
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw SOT-25 INCHES MILLIMETERSSYMBOL MIN MAX MIN MAX A 0.035 0.057 0.90 1.45 A1 0.000 0.006 0.00 0.15 A2 0.035 0.051 0.90 1.30 b 0.010 0.020 0.25 0.50 C 0.003 0.008 0.08 0.20 D 0.110 0.122 2.80 3.10 E 0.102 0.118 2.60 3.00 E1 0.059 0.069 1.50 1.75 L 0.014 0.022 0.35 0.55 e 0.037ref 0.95ref E1 0.075ref 1.90ref r 00 100 00 100
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw SOT-89 MILLIMETERS INCHESSYMBOL MIN MAX MIN MAX A 1.397 1.600 0.055 0.063 B 0.356 0.483 0.014 0.019 B 2.388 2.591 0.094 0.102 b1 0.406 0.533 0.016 0.021 C1 0.787 1.194 0.031 0.047 D 4.394 4.597 0.173 0.181 D1 1.397 1.753 0.055 0.069 E 1.448 1.549 0.057 0.061 H 0.381 0.432 0.015 0.017
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw TO-92 MILLIMETERS INCHESSYMBOL MIN MAX MIN MAX A 3.4 3.8 0.134 0.150 B 0.3 0.5 0.012 0.020 C 4.4 4.8 0.173 0.189 D 4.4 4.8 0.173 0.189 E 0.9 1.5 0.035 0.059 e 1.17 1.37 0.046 0.054 e1 2.39 2.69 0.094 0.106 L 12 16 0.472 0.630
Low-Voltage Adjustable Precision Shunt Regulator Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Reflow Condition (IR/Convection or VPR Reflow) Reference JEDEC Standard J-STD-020A Classification Reflow Profiles Convection or IR/Convction VPR Average Heating Rate(180°C to peak) 5 °C/second max. 10 °C/second max. Preheat Temperature(125±20°C) 120 seconds max. Temperature maintained above 180°C 10~150 seconds Time within 5°C of actual Peak Temperature 10~20 seconds 60 seconds Peak Temperature Range(Note 1) 219~225°C or 235~240°C 219~225°C or 235~240°C Cooling Rate 6°C /second max. 10 °C/second max. Time 25°C to Peak Temperature 6 minutes max. *1 The maximum peak temperatures for IR and VP reflow are depending on package dimensions. Package Reflow Conditions Pkg. Thickness ≥2.5mm and all bags Pkg. Thickness <2.5mm a n d Pkg. Volume ≥350 mm3 Pkg. Thickness <2.5mm a n d Pkg. Volume <350 mm3 Convection 219~225°C Convection 235~240 °C VPR 219~225°C VPR 235~240 °C IR/Convection 219~225°C IR/Convection 235~240 °C