Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS General Description Features The AN431-B is a three-terminal adjustable shunt regulator with guaranteed thermal stability over a full operation range. It features sharp turn-on characteristics, low temperature coefficient and low output impedance, which make it ideal substitute for Zener diode in applications such as switching power supply, charger and other adjustable regulators. · The output voltage of AN431-B can be set to any value between VREF (2.5V) and the corresponding maximum cathode voltage. The AN431-B precision reference is offered in two voltage tolerance: 0.5% and 1.0%. This IC is available in SOT-23 package. · · · · · · AN431-B Programmable Precise Output Voltage from 2.5V to 18V High Stability under Capacitive Load Low Temperature Deviation: 4.5mV Typical Low Equivalent Full-range Temperature Coefficient with 20PPM/oC Typical Sink Current Capacity from 1mA to 100mA Low Output Noise Wide Operating Range of -40 to 125oC Applications · · · · · Charger Voltage Adapter Switching Power Supply Graphic Card Precision Voltage Reference SOT-23 Figure 1. Package Type of AN431-B Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 1 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Pin Configuration N Package (SOT-23) ANODE 3 1 2 CATHODE REF Figure 2. Pin Configuration of AN431-B (Top View) Functional Block Diagram CATHODE 1 REF 2 + - VREF 3 ANODE Figure 3. Functional Block Diagram of AN431-B Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 2 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Ordering Information AN431 - Circuit Type G1: Green Voltage Tolerance A: 0.5% B: 1.0% TR: Tape &Reel Package N: SOT-23 B: AN431-B (20V) Package Temperature Range SOT-23 -40 to 125oC Voltage Tolerance Part Number Marking ID Packing Type 0.5% AN431AN-BTRG1 GB3 Tape & Reel 1.0% AN431BN-BTRG1 GB4 Tape & Reel BCD Semiconductor's products, as designated with "G1" suffix in the part number, are RoHS compliant and Green. Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 3 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit Cathode Voltage VKA 20 V Cathode Current Range (Continuous) IKA -100 to 150 mA Reference Input Current Range IREF 10 mA Power Dissipation PD 370 mW Junction Temperature TJ 150 Storage Temperature Range TSTG -65 to 150 oC ESD (Human Body Model) ESD 2000 V o C Note 1: Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extended periods may affect device reliability. Recommended Operating Conditions Parameter Symbol Min Max Unit Cathode Voltage VKA VREF 18 V Cathode Current IKA 1.0 100 mA Operating Ambient Temperature Range TA -40 125 o Jan. 2011 Rev. 1. 0 C BCD Semiconductor Manufacturing Limited 4 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Electrical Characteristics Operating Conditions: TA=25oC, unless otherwise specified. Parameter Reference Voltage 0.5% 1.0% Deviation of Reference Voltage Over Full Temperature Range Test Circuit Symbol 4 VREF 4 ∆VREF Conditions Min Typ Max 2.487 2.500 2.512 2.475 2.500 2.525 0 to 70oC 4.5 8 -40 to 85oC 4.5 10 -40 to 125oC 4.5 16 ∆VKA= 10V to VREF -1.0 -2.7 ∆VKA= 18V to 10V -0.5 -2.0 0.7 4 µA 0.4 1.2 µA VKA=VREF, IKA=10mA VKA=VREF IKA= 10mA Unit V mV Ratio of Change in Reference Voltage to the Change in Cathode Voltage 5 Reference Current 5 IREF Deviation of Reference Current Over Full Temperature Range 5 ∆IREF Minimum Cathode Current for Regulation 4 IKA (Min) VKA=VREF 0.4 1.0 mA Off-state Cathode Current 6 IKA (Off) VKA=18V, VREF=0 0.05 1.0 µA Dynamic Impedance 4 ZKA VKA=VREF, IKA=1 to 100mA f ≤ 1.0KHz 0.2 0.5 Ω θJC SOT-23 Thermal Resistance ∆VREF ∆VKA IKA=10mA IKA=10mA, R1=10KΩ, R2=∞ IKA=10mA, R1=10KΩ, R2=∞ TA=-40 to 125oC Jan. 2011 Rev. 1. 0 177.65 mV/ V oC/W BCD Semiconductor Manufacturing Limited 5 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Electrical Characteristics (Continued) R1 VKA VIN IKA VREF Figure 4. Test Circuit 4 for VKA=VREF R3 VIN VKA IKA R1 IREF VKA=VREF(1+R1/R2)+ IREF*R1 R2 VREF Figure 5. Test Circuit 5 for VKA>VREF VKA VIN IOFF Figure 6. Test Circuit 6 for IOFF Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 6 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Performance Characteristics 1.5 2.510 VKA = VREF Reference Current (µA) Reference Voltage (V) R1=10K,R2=Infinite IKA = 10mA 2.505 2.500 2.495 IKA=10mA 1.0 0.5 2.490 2.485 -60 -40 -20 0 20 40 60 80 100 120 0.0 -60 140 -40 -20 0 o 60 80 100 120 140 Figure 8. Reference Current vs. Ambient Temperature 800 VKA=VREF VKA=VREF 0 TA=25 C 0 TA=25 C 600 100 Cathode Current (µA) Cathode Current (mA) 40 Ambient Temperature ( C) Figure 7. Reference Voltage vs. Ambient Temperature 150 20 0 Ambient Temperature ( C) 50 0 400 200 0 -50 -200 -100 -2 -1 0 1 2 -1.0 3 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 Cathode Voltage (V) Cathode Voltage (V) Figure 9. Cathode Current vs. Cathode Voltage Figure 10. Cathode Current vs. Cathode Voltage Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 7 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Performance Characteristics (Continued) 1.8 VKA=18V 1.6 VREF=0 -0.9 ∆VREF / ∆VKA (mV/V) Off-State Cathode Current (µA) 2.0 1.4 1.2 1.0 0.8 0.6 0.4 VKA=3.5V to 18V -1.0 -1.1 -1.2 -1.3 0.2 -1.4 0.0 -40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 120 Ambient Temperature ( C) Ambient Temperature ( C) Figure 11. Off-State Cathode Current vs. Ambient Temperature Figure 12. Ratio of Delta Reference Voltage to the Ratio of Delta Cathode Voltage Output 70 0 TA=25 C 60 15K IKA=10mA 50 Voltage Gain (dB) 100 o o I KA 242 10µF 40 30 20 8.2K 10 0 -10 1k 10k 100k GND 1M Small Signal Frequency (Hz) Figure 13. Small Signal Voltage Gain vs. Frequency Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 8 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Performance Characteristics (Continued) Output IKA=10mA 1K Reference Impedance (Ω) o 10 TA=25 C IKA 50 1 GND 0.1 1K 10K 100K 1,000K Frequency (Hz) Figure 15. Reference Impedance vs. Frequency Cathode Current (mA) 20 18 VKA=10V:No oscillation 16 VKA=15V:No oscillation R1 (10K) 14 12 150 IKA Stable Stable 10 8 6 4 R2 VKA=VREF VKA=5V 2 0 0.01 0.1 1 10 Load Capacitance (µF) Figure 16. Stability Boundary Conditions vs. Load Capacitance Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 9 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Performance Characteristics (Continued) 5 Input and Output Voltage (V) Input Output 4 220 Pulse Generator f=100KHz 3 Output 2 50 1 0 GND 0 2 4 6 Time (µS) Figure 18. Pulse Response of Input and Output Voltage Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 10 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Application R3 VOUT VIN R1 VOUT=(1+R1/R2)*VREF VREF AN431-B R2 Figure 19. Shunt Regulator VIN VOUT R1 R4 R2 VOUT=(1+R2/R3)*VREF VREF AN431-B R3 Figure 20. High Current Shunt Regulator R2 VIN IOUT IOUT=VREF/R2 + IKA R1 AN431-B Figure 21. Current Source or Current Limit Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 11 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Typical Application (Continued) VIN AZ1117 R1 8.2K VOUT Adjust 5V, 1A R2 250 AN431-B R3 250 Figure 22. Precision 5V 1A Regulator R3 C1 R4 VOUT R2 680 R5 R1 U2 Q1 3 COMP C2 2 AN431-B PWM Controller VFB 4 PS521 Figure 23. PWM Converter with Reference Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 12 Data Sheet ADJUSTABLE PRECISION SHUNT REGULATORS AN431-B Mechanical Dimensions SOT-23 3.0 ° 2.0° 1.050(0.041)REF 7.0° R0.100(0.004) 0.900(0.035) 1.100(0.043) 0.0°~10.0° 0.020(0.001) 0.100(0.004) 0.200(0.008)MIN 2.800(0.110) 3.000(0.118) 0.550(0.022)REF 7.0° 0.080(0.003) 0.150(0.006) 1.200(0.047) 1.400(0.055) 2.300(0.091) 2.500(0.098) 0.920(0.036) 0.980(0.039) 0.100(0.004) GAUGE PLANE 4×R0.100(0.004) 0.500(0.020) 0.700(0.028) Unit: mm(inch) 0.390(0.015) 0.450(0.018) 1.900(0.075)REF Jan. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 13 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. 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