ADJUSTABLE PRECISION |
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ZH431 |
ZENER SHUNT REGULATOR |
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Issue 2 - February 1998 |
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DEVICE DESCRIPTION |
FEATURES |
The ZH431 is a three terminal adjustable shunt regulator offering excellent temperature stability and output current handling capability up to 30mA. The output voltage may be set to any chosen voltage between 2.5 and 36 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.They are also ideal for use in the feedback circuits of off line SMPUs as well as many general purpose regulator and reference applications where initial accuracy and low temperature coefficient are key requirements.
Note:
ZH431 is not recommended for new designs. Refer to ZR431
∙Surface mount SO8, SOT223,SOT23 and SOT89 packages
∙TO92 package
∙2% and 1% tolerance
∙Maximum temperature coefficient 55 ppm/°C
∙Temperature compensated for operation over the full temperature range
∙Programmable output voltage
∙50μA to 30mA 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
V ref
G
nd
4-15
ZH431
ABSOLUTE MAXIMUM RATING
Cathode Voltage (VZ) |
40V |
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Power Dissipation (Tamb=25°C, Tjmax=150°C) |
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Cathode Current |
50mA |
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SOT23 |
330mW |
Operating Temperature |
-40 to 85°C |
TO92 |
780mW |
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Storage Temperature |
-55 to 125°C |
SOT223 |
2W |
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Recommended Operating Conditions |
SO8 |
780mW |
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Min |
Max |
SOT89 |
1.5W |
Cathode Voltage |
Vref |
36V |
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Cathode Current |
50μA |
30mA |
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ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):Tamb=25°C
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SYMBOL |
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VALUE |
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PARAMETER |
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UNITS |
CONDITIONS |
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MIN |
TYP |
MAX |
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Reference Voltage |
2% |
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Vref |
2.45 |
2.50 |
2.55 |
V |
IL=10mA (Fig1), VZ=Vref |
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1% |
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2.475 |
2.50 |
2.525 |
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Deviation of Reference |
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Vdev |
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8.0 |
17 |
mV |
IL=10mA, VZ=Vref |
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Input Voltage over |
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Ta=full range (Fig1) |
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Temperature |
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Ratio of the change in |
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Vref |
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-0.7 |
-2.7 |
mV/V |
VZ from Vref to 10V |
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Reference Voltage to the |
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VZ |
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IZ=10mA (Fig2) |
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Change in Cathode |
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-0.6 |
-2.0 |
mV/V |
VZ from 10V to 36V |
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Voltage |
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IZ=10mA (Fig2) |
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Reference Input Current |
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Iref |
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0.15 |
1.0 |
μA |
R1=10k, R2=O/C, lL=10mA (Fig2) |
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Deviation of Reference |
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Iref |
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0.06 |
0.2 |
μA |
R1=10k, R2=O/C, IL=10mA |
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Input Current over |
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Ta=full range (Fig2) |
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Temperature |
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Minimum Cathode |
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IZmin |
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21 |
50 |
μA |
VZ=Vref |
(Fig1) |
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Current for Regulation |
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Dynamic Output Impedance |
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RZ |
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0.75 |
Ω |
VZ=Vref |
(Fig1), f=0Hz |
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 |
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Vmin |
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Vdev = Vmax - Vmin |
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T1 |
Temperature |
T2 |
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( ¤ )=Vdev x 1000000
Vref ppm °C Vref (T1−T2)
The dynamic output impedance, Rz, is defined as:
RZ = VZ IZ
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+RR12)
4-16
ZH431
TYPICAL CHARACTERISTICS
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200 |
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VoltageReferenceinChange(mV) |
5 |
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Vref= Vz |
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Iz= 10mA |
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0 |
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CurrentReference(nA) |
180 |
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160 |
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-5 |
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-10 |
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140 |
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-15 |
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120 |
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-20 |
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100 |
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-25 |
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-40 |
-20 |
0 |
20 |
40 |
60 |
80 |
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0 |
5 |
10 |
15 |
20 |
25 |
30 |
35 |
40 |
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Temperature (°C) |
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Cathode Voltage (V) |
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Reference Current v Temperature |
Change in Vref v Cathode Voltage |
Minimum Cathode Current (uA) |
26 |
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Vref= Vz |
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Dynamic Impedance (Ohms) |
100 |
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1mA |
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24 |
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22 |
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10 |
Vref=Vz |
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10mA |
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20 |
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1 |
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18 |
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16 |
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0.1 |
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14 |
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12 |
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0.01 |
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-40 |
-20 |
0 |
20 |
40 |
60 |
80 |
100 |
1k |
10k |
100k |
1M |
Temperature (°C) |
Frequency (Hz) |
Cathode Current v Temperature |
Dynamic Impedance v Frequency |
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2.52 |
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Iz= 10mA |
2.0 |
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2.51 |
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SOT223 |
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2.50 |
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1.0 |
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2.49 |
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PowerDissipation(W) |
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SOT89 |
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S08/T092 |
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2.48 |
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VoltageReference(V) |
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SOT23 |
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2.47 |
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0 |
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-40 |
-20 |
0 |
20 |
40 |
60 |
80 |
25 |
50 |
75 |
100 |
Temperature (°C) |
Ambient Temperature (°C) |
Power Dissipation Derating
Reference Voltage v Temperature
4-17