ZR431L Adjustable precision shunt regulator Summary Description The ZR431L is a three terminal adjustable shunt regulator offering excellent temperature stability and output current handling capability up to 25mA. The output voltage may be set to any chosen voltage between 1.24 and 10 volts by selection of two external divider resistors. The devices can be used as a replacement for zener diodes in many applications requiring an improvement in zener performance. The ZR431L is particularly used in the feedback control loop of switch mode power supplies. In this application the device 1.24 volt reference enables the generation of low voltage supplies, typically 3.3 volts or 3 volts. Features • 2.5% and 1% tolerance • Max. temperature coefficient 50 ppm/°C • Temperature compensated for operation over -40 to 85°C • 100mA to 25mA current sink capability • Surface mount SOT23 package Applications • Switch mode power supplies • Shunt regulator • Series regulator • Voltage monitor • Over voltage / under voltage protection Ordering information Device Pack Part mark Status Quantity per reel Reel size (inches) TOL % ZR431LF01TA SOT23 43M Active 3000 7 1 ZR431LF02TA SOT23 43L Active 3000 7 2.5 ZR431LC01STOB TO92 ZR431L01 Obsolete 1500 1 ZR431LC02STOB TO92 ZR431L02 Obsolete 1500 2.5 ZR431LC01L TO92 ZR431L01 Obsolete Loose 1 ZR431LC02L TO92 ZR431L02 Obsolete Loose 2.5 Issue 3 - April 2008 © Zetex Semiconductors plc 2008 1 www.zetex.com ZR431L Absolute maximum ratings Parameter Symbol Limit Unit VZ 10 V 50 mA Cathode voltage Cathode current Storage temperature TSTG -55 to 105 °C Junction temperature TJ -40 to 125 °C Power dissipation (at Tamb = 25°C unless otherwise stated) Package Value Unit 330 mW Parameter Min. Max. Cathode voltage VREF 10V Cathode current 100A 25mA Operating temperature -40°C 85°C SOT23 Recommended operating conditions Issue 3 - April 2008 © Zetex Semiconductors plc 2008 2 www.zetex.com ZR431L Block diagram Deviation of reference input voltage, Vdev, is defined as the maximum variation of the reference input voltage over the full temperature range. The average temperature coefficient of the reference input voltage, Vref is defined as: Vref ( ppmIC) = Vdev x1000000 Vref (T1 − T 2) The dynamic output impedance, Rz, is defined as: RZ = ΔVZ ΔI Z When the device is programmed with two external resistors, R1 and R2, (fig 2), the dynamic output impedance of the overall circuit, R’, is defined as: R' = RZ (1 + Issue 3 - April 2008 © Zetex Semiconductors plc 2008 3 R1 ) R2 www.zetex.com ZR431L Electrical characteristics (at Tamb = 25°C unless otherwise stated) Parameter Reference Voltage Symbol 2.5% Vref 1.0% Vref Min. 1.209 1.228 Typ. 1.24 1.24 Max. 1.271 1.252 Unit V V Conditions IL = 10mA (Fig1), VZ = Vref IL = 10mA, VZ = Vref Ta = full range (Fig 1) Deviation of Reference Input Voltage over Temperature Ratio of the change in Reference Voltage to the change in Cathode Voltage) Reference Input Current Vdev 4.0 8.0 mV ΔVref 0.5 2.0 mV/V 0.11 0.4 A R1 = 10k, R2 = O/C, lL = 10mA (fig2) Deviation of Reference Input Current over Temperature ⌬Iref 0.02 0.2 A R1 = 10k, R2 = O/C, IL = 10mA Ta = full range (Fig2) Minimum Cathode Current for Regulation Off-state Current IZmin 30 100 A IZoff 10 30 A 0.25 2 Ω Dynamic Output Impedance ΔVZ Iref RZ 0.02 VZ from Vref to 10V IZ = 10mA (Fig2) VZ = 10V, Vref = 0V (Fig3) VZ = Vref(Fig1), f = 0Hz, IL = 10mA DC Test circuits Fig 1 - Test Circuit for VZ = Vref Fig 2 - Test Circuit for VZ > Vref Fig 3 - Test Circuit for Off State current Issue 3 - April 2008 © Zetex Semiconductors plc 2008 4 www.zetex.com ZR431L Change in reference voltage (mV) Typical characteristics Reference Current (nA) 140 130 120 110 100 90 80 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 0 Dynamic Impedance (Ω) Minimum cathode current (µA) 24 22 20 18 -25 -10 5 20 35 50 65 80 95 110 VREF = VKA IK = 1mA 1 IK = 10mA 0.1 0.1 125 1 1.244 350 1.242 300 1.24 1.238 1.236 1.234 -25 -10 5 20 35 50 65 80 95 110 © Zetex Semiconductors plc 2008 100 250 200 150 100 50 -40 125 -25 -10 -5 20 35 50 65 80 95 110 125 Ambient temperature (°C) Power dissipation derating Temperature (°C) Reference voltage vs Temperature Issue 3 - April 2008 10 Frequency (kHz) Dynamic impedance vs frequency Power dissipation (mW) Reference voltage (V) 10 8 10 Temperature (°C) Minimum cathode current vs temperature 1.232 -42 6 4 100 26 16 -40 2 Cathode voltage (V) Change in reference voltage vs Cathode voltage Temperature (°C) Reference Current v Temperature 5 www.zetex.com ZR431L Application circuits Issue 3 - April 2008 © Zetex Semiconductors plc 2008 6 www.zetex.com ZR431L Typical characteristics Open loop gain (dB) 60 50 40 30 20 10 0 0 1 10 100 2 Repetitive pulse VKA 1 Input Voltage swing (V) Single pulse Output voltage swing (V) Frequency (kHz) Open loop gain vs frequency 0 5 2.5 VIN 0 -2.5 0 50 100 150 200 250 300 350 400 450 500 Time (μs) Pulse response Cathode current (mA) 30 25 20 15 10 5 0 0.01 0.1 1 10 100 1000 10000 Load capacitance (nF) Stability boundary conditions Issue 3 - April 2008 © Zetex Semiconductors plc 2008 7 www.zetex.com ZR431L SOT23 Package outline and pad layout details E 0.95 0.037 e e1 b 3 leads 2.0 0.079 L1 0.9 0.035 D E1 L A1 Dim. mm inches 0.8 0.031 A c Millimeters Inches Dim. Millimeters Min. Max. Min. Max. A - 1.12 - 0.044 e1 A1 0.01 0.10 0.0004 0.004 E 2.10 2.64 0.083 0.104 b 0.30 0.50 0.012 0.020 E1 1.20 1.40 0.047 0.055 c 0.085 0.20 0.003 0.008 L 0.25 0.60 0.0098 0.0236 D 2.80 3.04 0.110 0.120 L1 0.45 0.62 0.018 0.024 - - - - - e 0.95 NOM Min. 0.037 NOM Max. Inches 1.90 NOM Min. Max. 0.075 NOM Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches. Issue 3 - April 2008 © Zetex Semiconductors plc 2008 8 www.zetex.com ZR431L TO92 Package outline VZ 1 GND 2 Vref 3 Underside view Dim. Millimeters Inches Min. Max. Min. Max. A 4.32 4.95 0.170 0.195 b 0.36 0.51 0.014 0.020 E 3.30 3.94 0.130 0.155 e 2.41 2.67 0.095 0.105 e1 1.14 1.40 0.045 0.055 L 12.70 15.49 0.500 0.610 R 2.16 2.41 0.085 0.095 S1 1.14 1.52 0.045 0.060 W 0.41 0.56 0.016 0.022 D 4.45 4.95 0.175 0.195 *° 4° 6° 4° 6° Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches Issue 3 - April 2008 © Zetex Semiconductors plc 2008 9 www.zetex.com ZR431L Definitions Product change Zetex Semiconductors reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or service. Customers are solely responsible for obtaining the latest relevant information before placing orders. Applications disclaimer The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract, opportunity or consequential loss in the use of these circuit applications, under any circumstances. Life support Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Zetex Semiconductors plc. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Reproduction The product specifications contained in this publication are issued to provide outline information only which (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. Terms and Conditions All products are sold subjects to Zetex’ terms and conditions of sale, and this disclaimer (save in the event of a conflict between the two when the terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement. For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Zetex sales office. Quality of product Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer. To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. ESD (Electrostatic discharge) Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time. Devices suspected of being affected should be replaced. Green compliance Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with WEEE and ELV directives. Product status key: “Preview” Future device intended for production at some point. Samples may be available “Active” Product status recommended for new designs “Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect “Not recommended for new designs” Device is still in production to support existing designs and production “Obsolete” Production has been discontinued Datasheet status key: “Draft version” This term denotes a very early datasheet version and contains highly provisional information, which may change in any manner without notice. “Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance. However, changes to the test conditions and specifications may occur, at any time and without notice. “Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to specifications may occur, at any time and without notice. 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