ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ZR431L Issue 1 - NOVEMBER 1998 DEVICE DESCRIPTION FEATURES The ZR431L is a three terminal adjustable s h u n t r e g u l a t o r o f f e r i n g e x c e l l e nt 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 r e q u i r i n g a n i m p r ov e me nt i n z e n e r 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. • • • • Surface mount SOT23 package TO92 package 2.5% and 1% tolerance Maximum temperature coefficient 50 ppm/°C Temperature compensated for operation over the full temperature range Programmable output voltage 100µA to 25mA current sink capability Low output noise APPLICATIONS • • • • • Shunt regulator Series regulator Voltage monitor Over voltage/ under voltage protection Switch mode power supplies SCHEMATIC DIAGRAM VZ Vref Gnd ZR431L Power Dissipation (Tamb=25°C, Tjmax=150°C) SOT23 330mW TO92 600mW ABSOLUTE MAXIMUM RATING Cathode Voltage (VZ) 10V Cathode Current 50mA Operating Temperature -40 to 85°C Storage Temperature -55 to 125°C Recommended Operating Conditions Min Max Cathode Voltage VREF 10V Cathode Current 100µA 25mA ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):Tamb=25°C VALUE PARAMETER Reference Voltage SYMBOL MIN 2.5% Vref 1.0% TYP 1.209 1.24 1.228 1.24 MAX UNITS CONDITIONS 1.271 1.252 V IL=10mA (Fig1), VZ=Vref IL=10mA, VZ=Vref Ta=full range (Fig1) Deviation of Reference Input Voltage over Temperature Vdev 4.0 8.0 mV Ratio of the change in Reference Voltage to the Change in Cathode Voltage ∆Vref ∆VZ 0.5 2.0 mV/V VZ from Vref to 10V IZ=10mA (Fig2) 0.11 0.4 µA R1=10k,R2=O/C,lL=10mA(Fig2) ∆Iref 0.02 0.2 µA R1=10k, R2=O/C, IL=10mA Ta=full range (Fig2) IZmin 30 100 µA Off-state Current IZoff 10 30 µA VZ=10V, Vref =0V (Fig3) Dynamic Output Impedance RZ 0.25 2 Ω VZ=Vref (Fig1), f=0Hz, IL=10mA Reference Input Current Iref Deviation of Reference Input Current over Temperature Minimum Cathode Current for Regulation 0.02 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: Vmax Vdev x 1000000 Vref (ppm ⁄ °C)= Vref (T1−T2) The dynamic output impedance, Rz, is defined Vmin ∆VZ RZ = as: ∆IZ When the device is programmed with two Vdev = Vmax - Vmin external resistors, R1 and R2, (fig 2) , the dynamic output impedance of the overall circuit, R’, is defined as: R1 R’=Rz (1+ ) T1 T2 R2 Temperature ZR431L CONNECTION DIAGRAMS SOT23 Package Suffix – F TO92 Package Suffix – C Top View Bottom View ORDERING INFORMATION Part Number Package Tol % Part Mark ZR431LF02 SOT23 2.5 43L ZR431LF01 SOT23 1 43M ZR431LC02 TO92 2.5 ZR431L02 ZR431LC01 TO92 1 ZR431L01 ZR431L TYPICAL CHARACTERISTICS 0 140 Vref = Vz 130 Iz 10mA -1 Iz= 10mA -2 120 -3 -4 110 -5 -6 100 -7 90 80 -40 -8 -9 -20 0 20 40 60 80 0 Temperature (° C) 2 4 6 8 10 12 Cathode Voltage (V) Reference Current v Temperature Change in Vref v Cathode Voltage 26 100 Vref = Vz Vref = Vz 1mA 24 22 10 10mA 20 18 1 16 14 -40 -20 0 20 40 60 80 0.1 100 Temperature (° C) Cathode Current v Temperature 10k 100k Dynamic Impedance v Frequency 1.0 1.244 1.242 1k Frequency (Hz) Iz= 10mA 1.240 TO92 1.238 1.236 SOT23 1.234 1.232 -40 0 -20 0 20 40 60 Temperature (° C) Reference Voltage v Temperature 80 25 50 75 85 Ambient Temprature (° C) Power Dissipation Derating 100 ZR431L DC TEST CIRCUITS IL Input I ref IL Input VZ IZ R1 Fig 1 – Test Circuit for Vz=Vref Input IZ I ref R2 VZ I zoff 47nF 47nF Vref VZ 47nF Vref Fig 2 – Test Circuit for Vz>Vref 1-42 Fig 3 – Test Circuit for Off State current ZR431L APPLICATION CIRCUITS V+ Vout V+ Vout R1 R1 Vref Vref R2 Vout = R2 R1 1+ Vref Vout = R2 1+ R1 Vref R2 SHUNT REGULATOR HIGHER CURRENT SHUNT REGULATOR V+ ZSR*** V+ Vout Out In Common 30 R1 0.01µF Vref R1 R2 Vout Vref R2 Vout MIN = Vref + Vreg Vout = 1+ R1 Vref R2 Vout = 1+ R1 Vref R2 OUTPUT CONTROL OF A THREE TERMINAL FIXED REGULATOR SERIES REGULATOR V+ V+ OUTPUT R1A R1B Vref INPUT V on 2V Vref V off = V+ V TH = 2.5V R2A R2B Low limit = High limit = SINGLE SUPPLY COMPARATOR WITH TEMPERATURE COMPENSATED THRESHOLD 1+ R1B Vref R2B 1+ R1A Vref R2A OVER VOLTAGE / UNDER VOLTAGE PROTECTION CIRCUIT OUTPUT ZR431L TYPICAL CHARACTERISTICS VZ 60 Iz =10mA IZ 47k 50 240Ω 10µF 40 + 30 47k 20 - 10 0 100 10k 1k 100k Frequency (Hz) IZ = 10mA, TA = 25°C Test Circuit for Open Loop Voltage Gain Gain v Frequency 120Ω Input Monitor 2.0 VZ Repetitive Pulse Vz 1.0 Single Pulse Pulse Generator 50Ω 0 5.0 2.5 INPUT TA = 25°C 0 0 200 100 300 400 500 Test Circuit for Pulse Response Time (µs) Pulse Response Vref < VZ < 10, IZ = 10mA, TA = 25°C 30 Input VZ 150Ω 25 IZ 20 10k STABLE UNSTABLE STABLE 15 10 100µF 5 0 10p 100p 1n 10n .1µ 1µ 10µ Load Capacitance(F) Stability Boundary Conditions Test Circuit for Stability Boundary Conditions