Diodes ZHT431 User Manual

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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 rang e 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.

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

Applications

• Series and shunt regulator

• Voltage monitor

• Over voltage / under voltage protection

• Switch mode power supplies

Pin Assignments

GND

SOT23

(Top View)

V

Z

V

REF

Typical Application Circuit

ZHT431

Document number: DS32157 Rev. 11 - 2

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Absolute Maximum Ratings (Voltages to GND Unless Otherwise Stated)

Parameter Rating Unit

V

Cathode Voltage (VZ)

20

Cathode Current 150 mA
Operating Temperature -55 to 125 °C
Storage Temperature -55 to 150 °C
Power Dissipation

(T

= 25°C, T

amb

JMAX

= 150°C)

330 mW

Recommended Operating Conditions

Parameter Min Max Units

Cathode Voltage V

REF

Cathode Current 0.05 100 mA

- 20 V

ZHT431

Electrical Characteristics (Test conditions unless otherwise specified: T

Symbol Parameter

V

REF

Reference Voltage 2%
1%

0.5%

V

DEV

ΔV
ΔV

I

REF

ΔI

REF

I

Zmin

I

Zof

RZ

REF

Deviation of reference input voltage
over temperature

Ratio of the change in reference voltage
to the change in cathode voltage

Z

Reference input current

Deviation of reference input current
over temperature

Minimum cathode current for regulation
Off-state current
Dynamic output impedance

Deviation of reference input voltage, V

, is defined as the maximum variation of the reference input voltage over the full

DEV

Min. Typ. Max.

2.45

2.475

2.4875

temperature range.
The average temperature coefficient of the reference input voltage, V

Values

2.50

2.50

2.50

2.55

2.525

2.5125

10 30 mV

-1.85 -2.7 mV/V

-1.0 -2. mV/V

0.12 1.0 µA

0.04 0.2 µA

35 50 µA

0.1 µA

0.75 V

is defined as:

REF

= 25°C)

amb

Units Conditions

I

=10mA (Fig.1),

L

V

V

Z=VREF

I

=10mA, VZ=V

L

=full range (Fig1)

T

amb

from V

V

Z

=10mA (Fig.2)

I

Z

VZ from 10V to 20V

=10mA (Fig.2)

I

Z

R1=10k, R2=O/C,
l

=10mA (Fig.2)

L

R1=10k, R2=O/C,
IL=10mA T

(Fig.2)
V

Z=VREF

=20V, V

V

Z

V

Z=VREF

=1mA to 100mA

I

C

REF

to 10V

REF

=full range

amb

(Fig.1)

=0V(Fig.3)

REF

(Fig.1), f=0Hz,

The dynamic output impedance, R

, is defined as:

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:

ZHT431

Document number: DS32157 Rev. 11 - 2

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Typical Operating Conditions

170

160

150

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ZHT431

0

I = 10mA

Z

-5

140

130

120

Reference Current (nA)

110

100

90

-50 125-25 10007525 50

40

38

36

34

32

30

28

Minimum Cathode Current (µA)

26

Temperature (°C)

I vs. Tempe rature

REF

-10

-15

-20

Change in Reference Output Voltage (mV)

-25
02015510

Change in V vs. Ca thode Voltage

100

V = V

REF Z

10

1.0

Dynamic Impedance ( )Ω

Cathode Voltage (V)

REF

1mA

10mA

24

-50 125-25 10007525 50

2.50

2.500

2.498

2.496

2.494

2.492

Reference Voltage (V)

2.490

2.488

2.486

-50 125-25 10007525 50

ZHT431

Document number: DS32157 Rev. 11 - 2

Temperature (°C)

I vs. Temperature

ZMIN

Temperature ( C)°

V vs. Temperature

REF

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0.1
100 1K 10K 100K 1M

Dynamic Im pedance vs. Frequency

0.

0.4

0.3

0.2

Power Dissipation (W)

0.1

0

0

25 12550 10075

Frequency (Hz)

Ambient Temperature (°C)

Powe r Dissipation Derati n g

150

November 2010

© Diodes Incorporated