AT431 Low-Voltage Adjustable Precision Shunt Regulator Features Description ˙Low-Voltage Operation: Down to 1.24V ˙1% Reference-Voltage Tolerance ˙Adjustable Output Voltage, Vo=Vref to 12V ˙Low Operational Cathode Current….50μA ˙0.25Ω Typical Output Impedance ˙SOT-23-3 , SOT-23-5 and TO-92 Packages 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). Application 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 0.20Ω. 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. ˙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: [email protected] 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: [email protected] 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 θJA Symbol VKA IK IREF TOPR TSTG SOT-23-5 SOT-23-3 TO-92 Power Dissipation Limits 12 -20~20 -0.05~3 -30~+85 -55~+150 347 unit V mA mA o C o C o C/W 156 (TJ(max)-TA)/ θJA PD 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 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 Symbol Vref (TA = 25oC) Vref (TA = full o range 0~70 C) Vref(dev) Min. 1.228 1.221 Typ. 1.24 - Max. 1.252 1.259 Unit V V - 4 20 mV ∆ Vref /∆ VKA - -1.5 -2.7 Iref - 0.15 0.5 Iref(dev) - 0.05 0.3 IK(min) - 40 50 IK(off) - 0.001 0.1 µA | ZKA | - 0.20 0.4 Ω Conditions VKA= Vref (Figure 1) IK=10mA VKA= Vref IK=10mA (Figure 1) mV/V VKA= Vref to 12V IK=10mA (Figure 2) µA IK=10mA (Figure 2) R1=10KΩ µA IK=10mA R1=10KΩ (Figure 2) R2=open µA VKA= Vref (Figure 1) VKA=12V Vref =0V (Figure 3) VKA= Vref f≤1KHz 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: [email protected] 3 AT431 Low-Voltage Adjustable Precision Shunt Regulator Parameter Measurement Information Figure 1. Test Circuit for VKA=Vref Figure 2. Test Circuit for VKA>Vref VO= 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: [email protected] 4 AT431 Low-Voltage Adjustable Precision Shunt Regulator Figure 4. Figure 6. Figure 5. 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: [email protected] 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: [email protected] 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: [email protected] 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: [email protected] 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 (1.24V±1%). The output of the regulator, plus the forward voltage drop of the optocoupler LED (1.24+1.4=2.64V), determine the minimum 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: [email protected] 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: [email protected] 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 MAX 0.057 0.006 0.051 0.020 0.008 0.122 0.118 0.069 0.022 0.037ref 0.075ref 00 100 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: [email protected] 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: [email protected] 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: [email protected] 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(180°C to peak) Preheat Temperature(125±20°C) Temperature maintained above 180°C Time within 5°C of actual Peak Temperature Peak Temperature Range(Note 1) Cooling Rate Time 25°C to Peak Temperature 5°C/second max. 120 seconds max. 10~150 seconds 10~20 seconds 219~225°C or 235~240°C 6°C /second max. 6 minutes max. VPR 10°C/second max. 60 seconds 219~225°C or 235~240°C 10°C/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 Pkg. Thickness <2.5mm and Pkg. Volume <350 mm3 Convection 219~225°C VPR 219~225°C IR/Convection 219~225°C Convection 235~240°C VPR 235~240°C IR/Convection 235~240°C 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: [email protected] 14