A Product Line of Diodes Incorporated TLV431 1.24V COST EFFECTIVE SHUNT REGULATOR Description Pin Assignments TLV431_H6 (SC70-6 [SOT363]) The TLV431 is a three terminal adjustable shunt regulator offering excellent temperature stability and output current handling capability up to 20mA. The output voltage may be set to any chosen voltage between 1.24 and 18 volts by selection of two external divider resistors. CATHODE The TLV431 can be used as a replacement for zener diodes in many applications requiring an improvement in zener performance. 1 6 ANODE N/C 2 5 NC REF 3 4 NC (Top View) The TLV431 is available in 3 grades with initial tolerances of 1%, 0.5%, and 0.2% for the A, B and T grades respectively. TLV431_F (SOT23) REF Features 3 * Low Voltage Operation VREF = 1.24V * * * * * * * Temperature range -40 to +125C Reference Voltage Tolerance at +25C 0.2% TLV431T 0.5% TLV431B 1% TLV431A Typical temperature drift 4 mV (0C to +70C) 6 mV (-40C to +85C) 11mV (-40C to +125C) 80A Minimum cathode current 0.25 Typical Output Impedance Adjustable Output Voltage VREF to 18V Lead-Free Finish; RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. "Green" Device (Note 3) * Qualified to AEC-Q100 * 1 CATHODE ANODE 2 (Top View) TLV431_E5 (SOT25) N/C 1 N/C 2 CATHODE 3 5 ANODE 4 REF (Top View) Pin should be left floating or connect to anode Typical Application Circuit Secondary side regulated supply 3.3 V Optocoupler IF Primary side controller R3 R1 TLV431 R2 GND Notes: 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. All applicable RoHS exemptions applied. 2. See http://www.diodes.com for more information about Diodes Incorporated's definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green" products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. TLV431 Document number: DS32088 Rev. 6 - 2 1 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Absolute Maximum Ratings (@TA = +25C, unless otherwise specified.) Symbol Parameter VKA Cathode Voltage IKA IREF VIN ESD Susceptibility HBM MM CDM Rating Unit 20 V Continuous Cathode Current -20 to +20 mA Reference Input Current Range -0.05 to +3 mA Input Supply Voltage (Relative to Ground) -0.03 to +18 V 4 400 1 kV V kV Human Body Model Machine Model Charged Device Model (Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices.) Parameter Operating Junction Temperature Storage Temperature Rating -40 to +150 -65 to +150 Unit C C Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability. Unless otherwise stated voltages specified are relative to the ANODE pin. These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure. Recommended Operating Conditions (@TA = +25C, unless otherwise specified.) Symbol VKA Parameter Cathode Voltage Min Max Units VREF 18 V IKA Cathode Current 0.1 15 mA TA Operating Ambient Temperature Range -40 +125 C Package Thermal Data Package JA PDIS TA = +25C, TJ = +150C SOT23 SOT25 SC70-6 (SOT363) 380C/W 250C/W 330mW 500mW 380C/W 330mW TLV431 Document number: DS32088 Rev. 6 - 2 2 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Electrical Characteristics (@TA = +25C, unless otherwise specified.) Symbol Parameter Conditions VKA = VREF, TA = +25C VKA = VREF, TA = 0 to +70C VREF Reference Voltage VKA = VREF, TA = -40 to +85C VKA = VREF, TA = -40 to +125C Deviation of reference voltage over full temperature range VKA = VREF VREF VKA Ratio of change in reference voltage to the change in cathode voltage VKA for VREF to IREF Reference Input Current R1 = 10k, R2 = OC VREF(dev) IREF(dev) IKMIN IREF deviation over full temperature range Minimum cathode current for regulation TLV431A TLV431B TLV431T TLV431A TLV431B TLV431T TLV431A TLV431B TLV431T TLV431A TLV431B TLV431T Min 1.228 1.234 1.2375 1.221 1.227 1.230 1.215 1.224 1.228 1.209 1.221 1.224 Typ 1.24 1.24 1.24 Max 1.252 1.246 1.2425 1.259 1.253 1.250 1.265 1.259 1.252 1.271 1.265 1.255 TA = 0 to +70C 4 12 TA = -40 to +85C 6 20 TA = -40 to +125C 11 31 6V -1.5 -2.7 18V -1.5 -2.7 0.15 0.5 0.05 0.3 Units V mV mV/V TA = 0 to +70C R1 = 10k, R2 = OC VKA = VREF TA = -40 to +85C 0.1 0.4 TA = -40 to +125C 0.15 0.5 TA = 0 to +70C 55 80 TA = -40 to +85C 55 80 TA = -40 to +125C 55 100 A A A IK(OFF) Off state current VKA = 18V, VREF = 0V 0.001 0.1 A ZKA Dynamic output impedance VKA = VREF, f = <1kHz IK = 0.1 to 15mA 0.25 0.4 TLV431 Document number: DS32088 Rev. 6 - 2 3 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Typical Characteristics 56k 75k IK O/P S1 10mA 100nF 10k Test Circuit for VREF Measurement TLV431 Document number: DS32088 Rev. 6 - 2 4 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Typical Characteristics (cont.) TLV431 Document number: DS32088 Rev. 6 - 2 5 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Typical Characteristics (cont.) 3V 1k 470F 750 O/P Test Circuit for Input Noise Voltage O/P 6.8k IK 10F 180 5V ~ 4.3k Test Circuit for Phase Shift and Gain 100 100F 100 ~ O/P 50 Test Circuit for Reference Impedance TLV431 Document number: DS32088 Rev. 6 - 2 6 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Typical Characteristics (cont.) O/P Pulse Generator Test Circuit for Pulse Response TLV431 Document number: DS32088 Rev. 6 - 2 7 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Application Notes In a conventional shunt regulator application (Figure 1), an external series resistor (R3) is connected between the supply voltage, VIN, and the TLV431. R3 determines the current that flows through the load (IL) and the TLV431 (IK). The TLV431 will adjust how much current it sinks or "shunts" to maintain a voltage equal to VREF across its feedback pin. Since load current and supply voltage may vary, R3 should be small enough to supply at least the minimum acceptable IKMIN to the TLV431 even when the supply voltage is at its minimum and the load current is at its maximum value. When the supply voltage is at its maximum and IL is at its minimum, R3 should be large enough so that the current flowing through the TLV431 is less than 15mA. R3 is determined by the supply voltage, (VIN), the load and operating current, (IL and IK), and the TLV431's reverse breakdown voltage, VKA. IL R3 Vin Vout IK TLV431 R3 = R1 VIN - VKA IL + IK VREF where C1 R VKA = VREF x 1 + 1 R2 0.1F R2 and VKA = VOUT GND Figure 1 The values of R1 and R2 should be large enough so that the current flowing through them is much smaller than the current through R3 yet not too large that the voltage drop across them caused IREF affects the reference accuracy. The most frequent application of the TLV431 is in isolated low output voltage power supplies where the regulated output is galvanically isolated from the controller. As shown in Figure 2 the TLV431 drives current, IF, through the opto-coupler's LED which in turn drives the isolated transistor which is connected to the controller on the primary side of the power supply. This completes the feedback path through the isolation barrier and ensures that a stable isolated supply is maintained. Assuming a forward drop of 1.4V across the opto-coupler diode allows output voltages as low as 2.7V to be regulated. Regulated Supply Regulated Supply Optocoupler IF To controller To controller R3 R1 R1 VOUT = VREF 1 + R2 VOUT(max) - 2.7 VOUT - 2.7 > R3 IF(min) 15mA TLV431 R2 GND Figure 2. Using the TLV431 as the Regulating Element in an Isolated PSU TLV431 Document number: DS32088 Rev. 6 - 2 8 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Application Notes (cont.) Printed Circuit Board Layout Considerations The TLV431 in the SOT25 package has the die attached to pin 2, which results in an electrical contact between pin 2 and pin 5. Therefore, pin 2 of the SOT25 package must be left floating or connected to pin 5. TLV431 in the SC70-6 (SOT363) package has the die attached to pin 2 and 5, which results in an electrical contact between pins 2, 5 and pin 6. Therefore, pins 2 and 5 must be left floating or connected to pin 6. Other Applications of the TLV431 R3 Vout Vin R1 R4 R1 VOUT = VREF 1 + R2 ZXTP2039F IB R3 = Q1 VREF TLV431 VIN - VOUT ISH + IB R4 = C1 0.1F R2 ISH ISH hFE(min) VBE IB < IB 15mA GND Figure 3. High Current Shunt Regulator It may at times be required to shunt-regulate more current than the 15mA that the TLV431 is capable of. Figure 3 shows how this can be done using transistor Q1 to amplify the TLV431's current. Care needs to be taken that the power dissipation and/or SOA requirements of the transistor is not exceeded. ZXTN25020CFH Vin IOUT Vout Q1 R3 R1 IB VREF R1 VOUT = VREF 1 + R2 R3 = TLV431 IOUT(max) hFE(min) C1 0.1F VIN - ( VOUT + VBE ) IB < IB 15mA R2 GND Figure 4. Basic Series Regulator A very effective and simple series regulator can be implemented as shown in Figure 4 above. This may be preferable if the load requires more current than can be provided by the TLV431 alone and there is a need to conserve power when the load is not being powered. This circuit also uses one component less than the shunt circuit shown in Figure 3 above. TLV431 Document number: DS32088 Rev. 6 - 2 9 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Application Notes (cont.) Printed Circuit Board Layout Considerations (cont.) RS ZXTN25020CFH Vin Vout Q1 R3 IOUT VREF R1 VOUT = VREF 1 + R2 TLV431 IB R1 VIN - ( VOUT + VBE ) IB IOUT(max) hFE(min) V REF TLV431 R3 = C1 0.1F R2 RS = < IB 18mA VREF IOUT(max) GND Figure 5. Series Regulator with Current Limit Figure 5 adds current limit to the series regulator in Figure 4 using a second TLV431. For currents below the limit, the circuit works normally supplying the required load current at the design voltage. However should attempts be made to exceed the design current set by the second TLV431, the device begins to shunt current away from the base of Q1. This begins to reduce the output voltage and thus ensuring that the output current is clamped at the design value. Subject only to Q1's ability to withstand the resulting power dissipation, the circuit can withstand either a brief or indefinite short circuit. AP1084 Vin Vin VR1 Vout Vout GND R1 VREG R1 VOUT = VREF 1 + R 2 VOUT ( VREG + VREF ) VREF TLV431 (All features of the regulator such as short circuit protection, C1 0.1F R2 thermal shutdown, etc, are maintained.) GND Figure 6. Increasing Output Voltage of a Fixed Linear Regulator One of the useful applications of the TLV431 is in using it to improve the accuracy and/or extend the range and flexibility of fixed voltage regulators. In the circuit in Figure 6 above both the output voltage and its accuracy are entirely determined by the TLV431, R1 and R2. However the rest of the features of the regulator (up to 5A output current, output current limiting and thermal shutdown) are all still available. TLV431 Document number: DS32088 Rev. 6 - 2 10 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Application Notes (cont.) Printed Circuit Board Layout Considerations (cont.) AP1117 or AP1084 Vin Vin VR1 Vout Vout GND IB R3 R1 VOUT = VREF 1 + R2 VOUT ( VREG + VREF ) R1 1.2 V R3 = 0.1mA IB 18mA VREF TLV431 C1 0.1F VIN - ( VOUT - VREG ) IB (All features of the regulator R2 such as short circuit protection, thermal shutdown, etc, are maintained.) GND Figure 7. Adjustable Linear Voltage Regulator Figure 7 is similar to Figure 6 with adjustability added. Note the addition of R3. This is only required for the AP1117 due to the fact that its ground or adjustment pin can only supply a few micro-amps of current at best. R3 is therefore needed to provide sufficient bias current for the TLV431. Ordering Information Tol. 1% Part Number TLV431AE5TA TLV431AFTA TLV431AH6TA 0.5% TLV431BE5TA TLV431BFTA TLV431BH6TA 0.2% TLV431TFTA Package Part Mark Status Reel Size Tape Width SOT25 SOT23 SC70-6 (SOT363) SOT25 SOT23 SC70-6 (SOT363) SOT23 V1A V1A Active Active 7", 180mm 7", 180mm 8mm 8mm Quanity per Reel 3000 3000 V1A Active 7", 180mm 12mm 1000 V1B V1B Active Active 7", 180mm 7", 180mm 8mm 8mm 3000 3000 V1B Active 7", 180mm 12mm 1000 V1T Active 7", 180mm 8mm 3000 TLV431 Document number: DS32088 Rev. 6 - 2 11 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Package Outline Dimensions (All dimensions in mm.) Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version. SOT23 A B C H K M K1 D F J L G SOT25 A SOT25 Dim Min Max Typ A 0.35 0.50 0.38 B 1.50 1.70 1.60 C 2.70 3.00 2.80 D 0.95 H 2.90 3.10 3.00 J 0.013 0.10 0.05 K 1.00 1.30 1.10 L 0.35 0.55 0.40 M 0.10 0.20 0.15 N 0.70 0.80 0.75 0 8 All Dimensions in mm B C H K M N J L D SOT23 Dim Min Max Typ A 0.37 0.51 0.40 B 1.20 1.40 1.30 C 2.30 2.50 2.40 D 0.89 1.03 0.915 F 0.45 0.60 0.535 G 1.78 2.05 1.83 H 2.80 3.00 2.90 J 0.013 0.10 0.05 K 0.903 1.10 1.00 K1 -- -- 0.400 L 0.45 0.61 0.55 M 0.085 0.18 0.11 0 8 -- All Dimensions in mm SC70-6 (SOT363) A SC70-6 (SOT363) Dim Min Max Typ A 0.10 0.30 0.25 B 1.15 1.35 1.30 C 2.00 2.20 2.10 D 0.65 Typ F 0.40 0.45 0.425 H 1.80 2.20 2.15 J 0 0.10 0.05 K 0.90 1.00 1.00 L 0.25 0.40 0.30 M 0.10 0.22 0.11 0 8 All Dimensions in mm B C H K J M D F TLV431 Document number: DS32088 Rev. 6 - 2 L 12 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 Suggested Pad Layout Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version. SOT23 Dimensions Value (in mm) Z 2.9 X 0.8 Y 0.9 2.0 C 1.35 E Y Z C E X SOT25 C2 Z C2 Dimensions Value (in mm) Z 3.20 G 1.60 X 0.55 Y 0.80 C1 G C1 C2 2.40 0.95 Y X SC70-6 (SOT363) C2 Z C2 Dimensions Value (in mm) Z 2.5 G 1.3 X 0.42 Y 0.6 C1 1.9 C2 0.65 C1 G Y X TLV431 Document number: DS32088 Rev. 6 - 2 13 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated TLV431 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. 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