AT431

AT431 Preliminary Product Information 1.24V 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….50μA ․0.25Ω Typical Output Impedance ․SOT-23 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 0.20Ω. 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. Application ․Linear Regulators ․Voltage Reference for Power Circuit Block Diagram and Symbol Aimtron reserves the right without notice to change this circuitry and specifications. 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 1 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Equivalent Schematic Pin Assignments Ordering Information Part number AT431Z AT431UN AT431UN_GRE : Date Code Package TO-92 SOT-23 SOT-23, Green Marking Date Code Date Code ,Date Code with one bottom line *For more marking information, contact our sales representative directly 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 2 AT431 Preliminary Product Information 1.24V 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 PD Limits 12 -20~20 -0.05~3 -30~+85 -55~+150 347 156 (TJ(max)-TA)/ θJA 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 IK=10mA (Figure 1) 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) µA IK=10mA R1=10KΩ (Figure 2) µA IK=10mA R1=10KΩ R2=open (Figure 2) µA VKA= Vref (Figure 1) µA Ω 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 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 3 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Parameter Measurement Information Figure 2. Test Circuit for VKA>Vref Figure 1. Test Circuit for VKA=Vref VO= VKA=Vref VO= VKA=Vref *(1+R1/R2)+Iref *R1 Figure 3. Test Circuit for IK(off) 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 4 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Figure 4. Figure 5. Figure 6. Figure 7. 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 5 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Figure 8. Figure 9. Figure 10. 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 6 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Application Circuit 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 7 AT431 Preliminary Product Information 1.24V 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. 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 8 AT431 Preliminary Product Information 1.24V 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。 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 9 AT431 Preliminary Product Information 1.24V 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 7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 Fax: 886-3-563-0879 WWW: http://www.aimtron.com.tw 2/8/2006 REV:1.1 Email: service@aimtron.com.tw 10 AT431 Preliminary Product Information 1.24V Low-Voltage Adjustable Precision Shunt Regulator Reflow Profiles Profile Feature Sn-Pb Eutectic Assembly Large Body Small Body Pb-Free Assembly Large Body Pkg. thickness ≥2.5mm or Pkg. volume ≥350mm3 Small Body Pkg. thickness ≥2.5mm or Pkg. volume ≥350mm3 Pkg. thickness ≥2.5mm Pkg. thickness