ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ZHT431 ISSUE 3 – JANUARY 2003 DEVICE DESCRIPTION FEATURES The ZHT431 is a three terminal adjustable shunt regulator offering excellent 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. • Surface mount SOT223 and SOT23 packages • • • TO92 package • The devices can be used as a replacement for zener diodes in many applications requiring an improvement in zener performance. Temperature compensated for operation over the full temperature range • • • • Programmable output voltage 2% and 1% tolerance Maximum temperature coefficient 67 ppm/°C 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 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 Power Dissipation (Tamb=25°C) (Tjmax = 150°C) SOT23 330mW TO92 780mW SOT223 2W ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):Tamb=25°C SYMBOL PARAMETER MIN Reference Voltage 2% Vref 1% VALUE 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) † 0.75 Ω VZ=Vref (Fig1), f=0Hz, IC=1mA to 100mA Ratio of the change in Reference Voltage to the Change in Cathode Voltage ∆Vref Reference Input Current Iref 10 30 IL=10mA (Fig1), VZ=Vref ∆VZ Dynamic Output Impedance RZ -2.0 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 = min ∆IZ When the device is programmed with two external resistors, R1 and R2, (fig 2) , the dynamic output Vdev = Vmax - Vmin impedance of the overall circuit, R’, is defined as: R1 R’=Rz (1+ ) R2 T1 Temperature T2 4-29 ZHT431 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 0 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 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 nput 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 1+ Vout = R2 R1 Vref R2 S HUNT R E GULAT OR HIGHE R CUR R E NT S HUNT R E GULAT OR V+ Z S R *** + 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 OUT PUT CONT R OL OF A T HR E E T E R MINAL F IXE D R E GULAT OR S E R IE S R E GUL AT OR V+ V+ R 1A OUT PUT R 1B Vref INPUT V on 2V Vref V off = V+ R 2A V T H = 2.5V S INGLE S UPPLY COMPAR AT OR WIT H T E MPE R AT UR E COMPE NS AT E D T HR E S HOLD R 2B Low limit = 1+ High limit = 1+ R1B Vref R2B R1A Vref R2A OVE R VOLTAGE / UNDE R VOLT AGE PR OT E CT ION CIR CUIT 4-33 OUT PUT ZHT431 CONNECTION DIAGRAMS SOT23 Package Suffix – F SOT223 Package Suffix – G Top View Top View – Pin 4 floating or connected to pin 2 TO92 Package Suffix – C Bottom View ORDERING INFORMATION PART No TOL PACKAGE PARTMARK % ZHT431G02 2 SOT223 ZHT43102 ZHT431G01 1 SOT223 ZHT43101 ZHT431F02 2 SOT23 43D ZHT431F01 1 SOT23 43C ZHT431C02 2 TO92 ZHT43102 ZHT431C01 1 TO92 ZHT43101 4-34