ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ZHT431 ISSUE 2 – FEBRUARY 1997 DEVICE DESCRIPTION FEATURES The ZHT431 is a three terminal adjustable s hu n t r e g u l a t or o f f e r i n g e xc el l e nt temperature stability and output current handling capability up to 100mA. The device offers extended operating temperature range working from -55 to +125°C. The output voltage may be set to any chosen voltage between 2.5 and 20 volts by selection of two external divider resistors. • The devices can be used as a replacement for zener diodes in many applications r e qu i r i n g a n i mpr o ve me nt i n z e ner performance. • • • • • • • • Surface mount SO8, SOT89, SOT223 and SOT23 packages TO92 package 2% and 1% tolerance Maximum temperature coefficient 67 ppm/°C Temperature compensated for operation over the full temperature range Programmable output voltage 50µA to 100mA current sink capability Low output noise Wide temperature range -55 to +125°C APPLICATIONS • • • • Series and Shunt regulator Voltage monitor Over voltage/ under voltage protection Switch mode power supplies SCHEMATIC DIAGRAM VZ V ref Gnd 4-28 ZHT431 ABSOLUTE MAXIMUM RATING Power Dissipation (Tamb=25°C) (Tjmax = 150°C) SOT23 330mW TO92 780mW SOT223 2W SO8 780mW SOT89 1.5W Cathode Voltage (VZ) 20V Cathode Current 150mA Operating Temperature -55 to 125°C Storage Temperature -55 to 150°C Recommended Operating Conditions Min Max Cathode Voltage Vref 20V Cathode Current 50µA 100mA ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):Tamb=25°C VALUE SYMBOL PARAMETER MIN Reference Voltage 2% Vref 1% TYP MAX UNITS CONDITIONS 2.45 2.50 2.55 V 2.475 2.50 2.525 Deviation of Reference Input Vdev Voltage over Temperature mV IL=10mA, VZ=Vref Ta=full range (Fig1) -1.85 -2.7 mV/V VZ from Vref to 10V IZ=10mA (Fig2) -1.0 mV/V VZ from 10V to 20V IZ=10mA (Fig2) 0.12 1.0 µA R1=10k, R2=O/C, lL=10mA (Fig2) Deviation of Reference Input ∆Iref Current over Temperature 0.04 0.2 µA R1=10k, R2=O/C, IL=10mA Ta=full range (Fig2) Minimum Cathode Current for Regulation IZmin 35 50 µA VZ=Vref (Fig1) Off-state Current IZoff 0.1 µA VZ=20V, Vref=0V(Fig3) † Dynamic Output Impedance RZ 0.75 Ω Ratio of the change in Reference Voltage to the Change in Cathode Voltage ∆Vref ∆VZ Reference Input Current Iref 10 30 IL=10mA (Fig1), VZ=Vref -2.0 VZ=Vref (Fig1), f=0Hz, IC=1mA to 100mA 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: Vdev x 1000000 Vmax Vref (ppm ⁄ °C)= Vref (T1−T2) The dynamic output impedance, Rz, is defined as: ∆VZ RZ = Vmin ∆IZ When the device is programmed with two external Vdev = Vmax - Vmin resistors, R1 and R2, (fig 2) , the dynamic output impedance of the overall circuit, R’, is defined as: R1 R’=Rz (1+ ) R2 T1 Temperature T2 4-29 ZHT431 Change in Reference Output Voltage (mV) TYPICAL CHARACTERISTICS 170 Reference Current (nA) 160 150 140 130 120 110 100 90 -50 -25 0 25 50 75 100 125 Temperature ( °C) 0 -5 -10 -15 -20 -25 0 5 15 20 Change in Vref v Cathode Voltage 40 100 Vref=VZ Dynamic Impedance (Ω) 38 36 34 32 30 28 1mA 10 10mA 1.0 26 0.1 100 24 -50 -25 0 25 50 75 100 125 1k Temperature ( °C) 10k 100k 1M Frequency (Hz) Izmin vs. Temperature Dynamic Impedance v Frequency 2.0 2.502 1.8 2.500 SOT223 Power Dissipation (W) 1.6 Reference Voltage (V) 10 Cathode Voltage (V) Iref vs. Temperature Minimum Cathode Current (µA) IZ=10mA 2.498 2.496 2.494 2.492 2.490 SOT89 1.4 1.2 1.0 0.8 SO8/ TO92 0.6 0.4 SOT23 0.2 2.488 0 2.486 -50 -25 0 25 50 0 75 100 125 25 50 75 100 125 150 Temperature ( °C) Ambient Temperature ( °C) Vref vs. Temperature Power Dissipation Derating 4-30 ZHT431 TYPICAL CHARACTERISTICS Open Loop Voltage Gain (dB) 60 VZ IZ 15k 40 230 9µF + 20 8k25 0 100 1k 10k 100k - 1M IZ = 10mA, TA = 25°C Frequency (Hz) Gain v Frequency Test Circuit for Open Loop Voltage Gain 220 V Input Monitor 3.0 Z Voltage Swing (V) Repetitive pulse 2.0 Single pulse VZ 1.0 Pulse Generator 5.0 INPUT 0 0 0.2 0.4 0.6 0.8 1.0 Time (µs) TA = 25°C Test Circuit for Pulse Response Pulse Response 100 Cathode Current (mA) 50 0 Input 80 150 VZ IZ STABLE STABLE 10k 60 40 20 0 10p 100p 1000p 0.01µ 0.1µ 1µ Load Capacitance (F) Stability Boundary Conditions Vref < VZ < 20, IZ = 10mA, TA = 25°C Test Circuit for Stability Boundary Conditions 4-31 ZHT431 DC TEST CIRCUITS IL Input Input VZ I zoff Fig 1 – Test Circuit for Vz=Vref Fig 2 – Test Circuit for Vz>Vref Fig 3 – Test Circuit for Off State current † NOTE † Since the “Off State” disables all internal circuitry including leakage control, operating in this mode at high temperature is not recommended. 4-32 ZHT431 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+ R1A OUTPUT R1B Vref INPUT V on 2V Vref V off = V+ R2A V TH = 2.5V 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 4-33 OUTPUT ZHT431 CONNECTION DIAGRAMS SO8 Package Suffix – N8 SOT223 Package Suffix – G Top View Top View – Pin 4 floating or connected to pin 2 SOT23 Package Suffix – F TO92 Package Suffix – C Top View Bottom View SOT89 ORDERING INFORMATION PART No Package Suffix – Z TOL PACKAGE PARTMARK % ZHT431N802 2 SO8 ZHT43102 ZHT431N801 1 SO8 ZHT43101 ZHT431G02 2 SOT223 ZHT43102 ZHT431G01 1 SOT223 ZHT43101 ZHT431F02 2 SOT23 43D ZHT431F01 1 SOT23 43C ZHT431C02 2 TO92 ZHT43102 ZHT431C01 1 TO92 ZHT43101 ZHT431Z02 2 SOT89 43F ZHT431Z01 1 SOT89 43E Top View – Pin 4 floating or connected to pin 2 4-34