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ADJUSTABLE PRECISION ZENER SHUNT REGULATOR
ISSUE 2 - FEBRUARY 1997 DEVICE DESCRIPTION
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 +125C. 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.
ZHT431
FEATURES
* * * * * * * * * * * * *
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 50A to 100mA current sink capability Low output noise Wide temperature range -55 to +125C
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 125C Storage Temperature -55 to 150C Recommended Operating Conditions Min Max Cathode Voltage Vref 20V Cathode Current 50A 100mA Power Dissipation (Tamb=25C) (Tjmax = 150C) SOT23 330mW TO92 780mW SOT223 2W SO8 780mW SOT89 1.5W
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):Tamb=25C
PARAMETER Reference Voltage
SYMBOL
VALUE MIN TYP MAX UNITS CONDITIONS IL=10mA (Fig1), VZ=Vref IL=10mA, VZ=Vref Ta=full range (Fig1) VZ from Vref to 10V IZ=10mA (Fig2) VZ from 10V to 20V IZ=10mA (Fig2) R1=10k, R2=O/C, lL=10mA (Fig2) R1=10k, R2=O/C, IL=10mA Ta=full range (Fig2) VZ=Vref (Fig1) VZ=20V, Vref=0V(Fig3) VZ=Vref (Fig1), f=0Hz, IC=1mA to 100mA 2.45 2.50 2.55 V 2.475 2.50 2.525 10 30 mV mV/V mV/V A A A A
2% Vref 1%
Deviation of Reference Input Vdev Voltage over Temperature Ratio of the change in Reference Voltage to the Change in Cathode Voltage Reference Input Current Vref VZ
-1.85 -2.7 -1.0 -2.0
Iref
0.12 1.0 0.04 0.2 35 50 0.1
Deviation of Reference Input Iref Current over Temperature Minimum Cathode Current for Regulation Off-state Current Dynamic Output Impedance IZmin IZoff RZ
0.75
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
TYPICAL CHARACTERISTICS
170 160
Change in Reference Output Voltage (mV)
0
IZ=10mA
Reference Current (nA)
150 140 130 120 110 100 90 -50 -25 0 25 50 75 100 125
-5
-10
-15
-20
-25 0 5 10 15 20
Temperature ( C)
Cathode Voltage (V)
Iref vs. Temperature
40
Change in Vref v Cathode Voltage
100 Vref=VZ
Minimum Cathode Current (A)
36 34 32 30 28 26 24 -50 -25 0 25 50 75 100 125
Dynamic Impedance ()
38
1mA
10 10mA
1.0
0.1 100
1k
10k
100k
1M
Temperature ( C)
Frequency (Hz)
Izmin vs. Temperature
2.502 2.500
Dynamic Impedance v Frequency
2.0 1.8 1.6 SOT223 SOT89
Reference Voltage (V)
2.498 2.496 2.494 2.492 2.490 2.488 2.486 -50 -25 0 25 50 75 100 125
Power Dissipation (W)
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0
SO8/ TO92
SOT23
25
50
75
100
125
150
Temperature ( C)
Ambient Temperature ( C)
Vref vs. Temperature
Power Dissipation Derating
4-30
ZHT431
TYPICAL CHARACTERISTICS
60 VZ
Open Loop Voltage Gain (dB)
40 9F
15k
IZ
230
20 8k25
+ -
0
100
1k
10k
100k
1M
Frequency (Hz)
IZ = 10mA, TA = 25C
Gain v Frequency
Test Circuit for Open Loop Voltage Gain
220
3.0 Repetitive pulse
Input Monitor
V
Z
Voltage Swing (V)
2.0 Single pulse 1.0 VZ Pulse Generator 50
0 5.0 0 0 0.2 0.4 INPUT
0.6
0.8
1.0
Time (s)
TA = 25C
Pulse Response
100
Test Circuit for Pulse Response
Input 150 VZ
Cathode Current (mA)
80 STABLE 60 STABLE
IZ 10k
40
20
0 10p 100p 1000p 0.01 0.1 1
Load Capacitance (F)
Vref < VZ < 20, IZ = 10mA, TA = 25C
Stability Boundary Conditions
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 Vref Vref R2
R1
R2
Vout =
1+
R1 R2
Vref
Vout =
1+
R1 R2
Vref
SHUNT REGULATOR
HIGHER CURRENT SHUNT REGULATOR
V+ ZSR*** In Common Out
V+
Vout
30
R1 0.01F Vref R1 R2 Vref R2 Vout
Vout MIN = Vref + Vreg Vout = 1+ R1 R2 OUTPUT CONTROL OF A THREE TERMINAL FIXED REGULATOR Vref Vout = 1+ R1 R2 SERIES REGULATOR Vref
V+
V+
OUTPUT INPUT V on V TH = 2.5V 2V
R1A
R1B Vref OUTPUT
Vref R2A R2B
V off = V+
Low limit =
1+
R1B R2B
Vref
High limit =
1+
R1A R2A
Vref
SINGLE SUPPLY COMPARATOR WITH TEMPERATURE COMPENSATED THRESHOLD
OVER VOLTAGE / UNDER VOLTAGE PROTECTION CIRCUIT
4-33
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
ORDERING INFORMATION
PART No TOL PACKAGE PARTMARK % ZHT431N802 ZHT431N801 ZHT431G02 ZHT431G01 ZHT431F02 ZHT431F01 ZHT431C02 ZHT431C01 ZHT431Z02 ZHT431Z01 2 1 2 1 2 1 2 1 2 1 SO8 SO8 SOT223 SOT223 SOT23 SOT23 TO92 TO92 SOT89 SOT89 ZHT43102 ZHT43101 ZHT43102 ZHT43101 43D 43C ZHT43102 ZHT43101 43F 43E 4-34
SOT89
Package Suffix - Z
Top View - Pin 4 floating or connected to pin 2

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