Page 1
ADJUSTABLE PRECISION
V
Z
G
nd
V
ref
ZENER SHUNT REGULATOR
Issue 2 - February 1998
ZH431
DEVICE DESCRIPTION
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
SCHEMATIC DIAGRAM
FEATURES
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
•
4-15
Page 2
ZH431
ABSOLUTE MAXIMUM RATING
Cathode Voltage (VZ) 40V
Cathode Current 50mA
Operating Temperature -40 to 85°C
Storage Temperature -55 to 125°C
Recommended Operating Conditions
Min Max
Cathode Voltage Vref 36V
Cathode Current 50µA 30mA
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise
stated):T
PARAMETER
Reference Voltage 2%
1%
Deviation of Reference
Input Voltage over
Temperature
Ratio of the change in
Reference Voltage to the
Change in Cathode
Voltage
Reference Input Current I
Deviation of Reference
Input Current over
Temperature
Minimum Cathode
Current for Regulation
Dynamic Output Impedance R
Deviation of reference input voltage, V
input voltage over the full temperature range.
The average temperature coefficient of the reference input voltage, V
Vmax
Vmin
=25°C
amb
Vdev = Vmax - Vmin
SYMBOL
V
ref
V
dev
∆
V
ref
∆
V
Z
ref
∆
I
ref
I
Zmin
Z
VALUE
MIN TYP MAX
2.45
2.475
is defined as the maximum variation of the reference
dev,
Power Dissipation (T
amb
SOT23 330mW
TO92 780mW
SOT223 2W
SO8 780mW
SOT89 1.5W
UNITS CONDITIONS
2.50
2.55
2.50
VI
2.525
=10mA (Fig1), VZ=V
L
8.0 17 mV IL=10mA, VZ=V
Ta=full range (Fig1)
-0.7 -2.7 mV/V VZ from V
I
=10mA (Fig2)
Z
-0.6 -2.0 mV/V V
0.15 1.0
0.06 0.2
21 50
0.75
µA
µA
µA
Ω
from 10V to 36V
Z
I
=10mA (Fig2)
Z
R1=10k, R2=O/C, lL=10mA (Fig2)
R1=10k, R2=O/C, IL=10mA
T
=full range (Fig2)
a
VZ=V
ref
VZ=V
ref
is defined as:
ref
V
(
ppm
ref
⁄
The dynamic output impedance, Rz, is defined as:
V
∆
Z
R
=
Z
∆
I
Z
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’=R
(1+
z
R
R
=25°C, T
to 10V
ref
(Fig1)
(Fig1), f=0Hz
V
dev
°C)=
V
ref
1
)
2
=150°C)
jmax
ref
ref
x 1000000
(T1−T2)
T1 T2
Temperature
4-16
Page 3
TYPICAL CHARACTERISTICS
ZH431
200
180
160
140
120
Reference Current (nA)
100
-40 -20 80
020 6040
Temperature (°C)
Reference Current v Temperature
26
24
22
20
18
16
14
12
-40 -20 80
Minimum Cathode Current (uA)
020 6040
Temperature (°C)
Cathode Current v Temperature
2.52
2.51
2.50
2.49
2.48
Reference Voltage (V)
2.47
-40 -20 80
020 6040
Temperature (°C)
Reference Voltage v Temperature
Vref= Vz
Iz= 10mA
Vref= Vz
Iz= 10mA
5
0
-5
-10
-15
-20
-25
0 5 30 35
Change in Reference Voltage (mV)
10 15 2520
Cathode Voltage (V)
Change in Vref v Cathode Voltage
100
Vref=Vz
10
1
0.1
0.01
Dynamic Impedance (Ohms)
100 1k
10k 100k 1M
Frequency (Hz)
Dynamic Impedance v Frequency
2.0
SOT223
1.0
Power Dissipation (W)
0
25 75
SOT89
S08/T092
SOT23
50
Ambient Temperature (°C)
Power Dissipation Derating
40
1mA
10mA
100
4-17
Page 4
ZH431
70
60
50
40
30
20
10
Open Loop Gain (dB)
0
100
3.0
2.0
1.0
0
5
Voltage Swing (V)
0
00.05
TYPICAL CH ARACTERISTICS
10k
INPUT
100k
1M
Test Circuit for Open Loop Voltage Gain
Input Monitor
TA = 25°C
1k
Frequency (Hz)
Gain v Frequency
REPETITIVE
PULSE
SINGLE
PULSE
0.1 0.15 0.250.2
Time (µs)
Pulse Response
IZ
15k
9µF
+
= 10mA,
IZ
Pulse
Generator
8k25
TA= 25°C
Ω
50
220
-
Ω
Test Circuit for Pulse Response
230
V
Z
Ω
V
Z
30
25
Cathode Current (mA)
20
Stable
15
10
5
0
10p 100p
Unstable
1000p 0.01µ 0.1µ
Load Capacitance (F)
Stability Boundary Conditions
Stable
Input
150
IZ
10k
1µ
Vref < VZ < 40, IZ = 10mA, TA = 25°C
Test Circuit for Stability Boundary Conditions
4-18
VZ
Page 5
DC TEST CIRCUITS
L
I
Input
ZH431
Fig 1 – Test Circuit for Vz=V
ref
Fig 2 – Test Circuit for Vz>V
ref
4-19
Page 6
V
ZH431
APPLICATION CIRCUITS
V+ Vout
R1
Vref
R2
R1
1 +
Vout =
SHUNT REGULATOR
+
ZSR***
In
Common
Vout = Vref + Vreg
MIN
Vout = 1 +
OUTPUT CONTROL OF A
THREE TERMINAL FIXED REGULATOR
Vref
R2
Vout
Out
R1
Vref
R2
R1
Vref
R2
V+ Vout
R1
Vref
R2
30
0.01µF
R1
1 +
Vref
R2
R1
R2
R1
Vref
R2
Vout =
HIGHER CURRENT SHUNT REGULATOR
V+
Vref
Vout = 1 +
SERIES REGULATOR
Vout
V+
INPUT
= 2.5V
V
TH
SINGLE SUPPLY COMPARATOR
WITH TEMPERATURE
COMPENSATED THRESHOLD
OUTPUT
V
V
V+
R1A
2V
on
= V+
off
Vref
R2A
R1B
R2B
R1B
1 +
Low limit =
High limit =
OVER VOLTAGE / UNDER VOLTAGE
Vref
R2B
R1A
1 +
Vref
R2A
PROTECTION CIRCUIT
Vref
OUTPUT
4-20
Page 7
CONNECTION DIAGRAMS
SO8 Package Suffix – N8
ZH431
SOT223 Package Suffix – G
Top View
SOT23 Package Suffix – F
Top View
ORDERING INFORMATION
Part Number Package Tol.%Part Mark
ZH431C01 TO92 1.0 ZH43101
ZH431C02 TO92 2.0 ZH43102
ZH431G01 SOT223 1.0 ZH43101
ZH431G02 SOT223 2.0 ZH43102
ZH431F01 SOT23 1.0 43H
ZH431F02 SOT23 2.0 43G
ZH431Z01 SOT89 1.0 43H
ZH431Z02 SOT89 2.0 43G
ZH431N801 SO8 1.0 ZH43101
ZH431N802 SO8 2.0 ZH43102
Top View –
Pin 4 floating or connected to pin 2
TO92 Package Suffix – C
Bottom View
SOT89 Package Suffix – Z
Top View –
Pin 4 floating or connected to pin 2
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