A Product Line of
Diodes Incorporated
ZHT431
ADJUSTABLE PRECISION ZENER SHUNT REGULATOR
Description
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.
The devices can be used as a replacement for zener
diodes in many applications requiring an improvement in
zener performance.
Pin Assignments
SOT23
V
Z
GND
V
REF
Features
•
•
•
•
•
•
•
•
•
Surface mount SOT23 package
0.5%, 1% and 2% tolerance
Maximum temperature coefficient 67ppm/°C
Temperature compensated for operation over the full
temperature range
Programmable output voltage
50μA to 100mA current sink capability
Low output noise
Available in “Green” Molding Compound (See
page 7)
Wide temperature range -55 to +125°C
(Top View)
Applications
•
•
•
•
Series and shunt regulator
Voltage monitor
Over voltage / under voltage protection
Switch mode power supplies
Typical Application Circuit
ZHT431
Document number: DS32157 Rev. 11 - 2
1 of 8
www.diodes.com
November 2010
© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZHT431
Absolute Maximum Ratings
(Voltages to GND Unless Otherwise Stated)
Parameter
Cathode Voltage (V
Z
)
Cathode Current
Operating Temperature
Storage Temperature
Power Dissipation
(T
amb
= 25°C, T
JMAX
= 150°C)
Rating
20
150
-55 to 125
-55 to 150
330
Unit
V
mA
°C
°C
mW
Recommended Operating Conditions
Parameter
Cathode Voltage V
REF
Cathode Current
Min
-
0.05
Max
20
100
Units
V
mA
Electrical Characteristics
Symbol
V
REF
V
DEV
ΔV
REF
ΔV
Z
Reference Voltage
(Test conditions unless otherwise specified: T
amb
= 25°C)
Parameter
2%
1%
0.5%
Min.
2.45
2.475
2.4875
Values
Typ.
2.50
2.50
2.50
10
-1.85
-1.0
Max.
2.55
2.525
2.5125
30
-2.7
-2.
1.0
0.2
50
0.1
0.75
Units
V
mV
mV/V
mV/V
µA
µA
µA
µA
V
Conditions
I
L
=10mA (Fig.1),
V
Z
=V
REF
I
L
=10mA, V
Z
=V
REF
T
amb
=full range (Fig1)
V
Z
from V
REF
to 10V
I
Z
=10mA (Fig.2)
V
Z
from 10V to 20V
I
Z
=10mA (Fig.2)
R1=10k, R2=O/C,
l
L
=10mA (Fig.2)
R1=10k, R2=O/C,
I
L
=10mA T
amb
=full range
(Fig.2)
V
Z
=V
REF
(Fig.1)
V
Z
=20V, V
REF
=0V(Fig.3)
V
Z
=V
REF
(Fig.1), f=0Hz,
I
C
=1mA to 100mA
Deviation of reference input voltage
over temperature
Ratio of the change in reference voltage
to the change in cathode voltage
I
REF
ΔI
REF
Reference input current
Deviation of reference input current
over temperature
Minimum cathode current for regulation
Off-state current
Dynamic output impedance
0.12
0.04
35
I
Zmin
I
Zoff
R
Z
Deviation of reference input voltage, V
DEV
, 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, V
REF
is defined as:
The dynamic output impedance, R
Z
, is defined as:
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:
ZHT431
Document number: DS32157 Rev. 11 - 2
2 of 8
www.diodes.com
November 2010
© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZHT431
Typical Operating Conditions
170
160
Reference Current (nA)
0
I
Z
= 10mA
Change in Reference Output Voltage (mV)
-5
150
140
130
120
110
100
90
-10
-15
-20
-50
-25
0
25
50 75 100 125
Temperature (°C)
I
R EF
vs. Temperature
-25
0
10
15
Cathode Voltage (V)
Change in V
REF
vs. Cathode Voltage
V
REF
= V
Z
5
20
40
38
100
1mA
Minimum Cathode Current (µA)
Dynamic Impedance (
Ω
)
36
34
32
30
28
26
24
10
10mA
1.0
-50
-25
0
25
50 75 100 125
Temperature (°C)
I
Z MIN
vs. Temperature
0.1
100
10K
100K
Frequency (Hz)
Dynamic Impedance vs. Frequency
1K
1M
2.502
2.500
0.5
0.4
2.498
Reference Voltage (V)
2.496
2.494
2.492
2.490
Power Dissipation (W)
-50
-25
0
25
50 75 100 125
Temperature ( °C)
V
REF
vs. Temperature
0.3
0.2
0.1
2.488
2.486
0
0
25
50
75
100
125
Ambient Temperature (°C)
Power Dissipation Derating
150
ZHT431
Document number: DS32157 Rev. 11 - 2
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November 2010
© Diodes Incorporated
A Product Line of
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ZHT431
Typical Operating Conditions
(Cont.)
60
Open Loop Vol t age Gai n (dB)
V
Z
I
Z
40
9μF
230
15k
20
8k25
+
-
0
100
1k
10k
100k
1M
Frequency (Hz)
I
Z
= 10mA, T
A
= 25°C
Gain v Frequency
Test Circuit for Open Loop Voltage Gain
220
3.0
Repetitive pulse
Input Monitor
V
Z
Vol t ag e Sw i ng (V)
2.0
Single pulse
1.0
V
Z
Pulse
Generator
50
0
5.0
0
0
0.2
0.4
INPUT
0.6
0.8
1.0
Time ( µs)
T
A
= 25°C
Pulse Response
100
Test Circuit for Pulse Response
150
V
Z
Input
80
STABLE
60
STABLE
Cat hod e Curr ent (m A)
I
Z
10k
40
20
0
10p
100p
1000p
0.01µ
0.1µ
1µ
Load Capacitance (F)
V
ref
< V
Z
< 20, I
Z
= 10mA, T
A
= 25°C
Stability Boundary Conditions
ZHT431
Document number: DS32157 Rev. 11 - 2
Test Circuit for Stability Boundary Conditions
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© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZHT431
DC Test Circuits
I
L
Input
V
Z
I
Z
I
L
Input
V
Z
I
Z
Input
V
Z
I
ZOFF
I
ref
R1
I
ref
V
ref
R2
V
ref
Fig 1 - Test circuit for V
Z
= V
ref
Fig 2 - Test circuit for V
Z
> V
ref
Fig 3 - Test circuit for
Off state current
†
ZHT431
Document number: DS32157 Rev. 11 - 2
5 of 8
www.diodes.com
November 2010
© Diodes Incorporated
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