Diodes ZR431L User Manual

ZR431L
Adjustable precision shunt regulator

Summary

Description

The ZR431L is a three terminal adjustable shunt regulator offering excellent
temperature stability and output current handling capability up to 25mA.
The output voltage may be set to any chosen voltage between 1.24 and
10 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.

The ZR431L is particularly used in the feedback control loop of switch mode
power supplies. In this application the device 1.24 volt reference enables
the generation of low voltage supplies, typically 3.3 volts or 3 volts.

Features

• 2.5% and 1% tolerance

• Max. temperature coefficient 50 ppm/°C

• Temperature compensated for operation over -40 to 85°C

• 100mA to 25mA current sink capability

• Surface mount SOT23 package

Applications

• Switch mode power supplies

• Shunt regulator

• Series regulator

• Voltage monitor

• Over voltage / under voltage protection

Ordering information

Device Pack Part mark Status Quantity

per reel

ZR431LF01TA SOT23 43M Active 3000 7 1

ZR431LF02TA SOT23 43L Active 3000 7 2.5

ZR431LC01STOB TO92 ZR431L01 Obsolete 1500 1

ZR431LC02STOB TO92 ZR431L02 Obsolete 1500 2.5

ZR431LC01L TO92 ZR431L01 Obsolete Loose 1

ZR431LC02L TO92 ZR431L02 Obsolete Loose 2.5

Reel size

(inches)

TOL %

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ZR431L

Absolute maximum ratings

Parameter Symbol Limit Unit

Cathode voltage V

Cathode current 50 mA

Storage temperature T

Junction temperature T

Z

STG

J

10 V

-55 to 105 °C

-40 to 125 °C

Power dissipation (at T

Package Value Unit

SOT23 330 mW

= 25°C unless otherwise stated)

amb

Recommended operating conditions

Parameter Min. Max.

Cathode voltage V

Cathode current 100␮A25mA

Operating temperature -40°C 85°C

REF

10V

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Block diagram

)21(

0

)(

TTV

xV

ppmICVref

ref

dev

−

=

Z

Z

Z

I

V

R

Δ

Δ

=

)

1

1('

R

R

RR

Z

+=

ZR431L

Deviation of reference input voltage, V
the maximum variation of the reference input voltage
over the full temperature range.

The average temperature coefficient of the reference
input voltage, V

is defined as:

ref

, is defined as

dev

100000

The dynamic output impedance, R

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:

, is defined as:

z

2

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ZR431L

Z

ref

V

V

Δ

Δ

Electrical characteristics (at T

= 25°C unless otherwise stated)

amb

Parameter Symbol Min. Typ. Max. Unit Conditions

Reference Voltage 2.5%

1.0%

Deviation of Reference
Input Voltage over

V

ref

V

ref

V

dev

1.209

1.228

1.24

1.24

1.271

1.252

VVIL = 10mA (Fig1), VZ = V

4.0 8.0 mV IL = 10mA, VZ = V
Ta = full range (Fig 1)

Temperature
Ratio of the change in

Reference Voltage to the
change in Cathode

0.5 2.0 mV/V

VZ from V
I

= 10mA (Fig2)

Z

Voltage)
Reference Input Current I

Deviation of Reference
Input Current over
Temperature

Minimum Cathode
Current for Regulation

Off-state Current I

ref

⌬I

I

Zmin

Zoff

ref

0.02 0.11 0.4 ␮A R1 = 10k, R2 = O/C,
l

= 10mA (fig2)

L

0.02 0.2 ␮A R1 = 10k, R2 = O/C,
IL = 10mA Ta = full

range (Fig2)

30 100 ␮A

10 30 ␮AVZ = 10V, V

(Fig3)

Dynamic Output
Impedance

R

Z

0.25 2

Ω

VZ = V

ref

= 10mA

I

L

ref

ref

to 10V

ref

= 0V

ref

(Fig1), f = 0Hz,

DC Test circuits

Fig 1 - Test Circuit for V

= V

Z

Fig 2 - Test Circuit for VZ > V

ref

Fig 3 - Test Circuit for Off State

ref

current

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Typical characteristics

ZR431L

140

130

120

110

100

Reference Current (nA)

90

80

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (°C)

Reference Current v Temperature

26

24

22

20

18

Minimum cathode current (µA)

16

-40 -25 -10 5 20 35 50 65

80 95

Temperature (°C)

Minimum cathode current vs temperature

110 125

0

-1

-2

-3

-4

-5

-6

-7

-8

Change in reference voltage (mV)

-9
0

42

Cathode voltage (V)

6

Change in reference voltage vs Cathode voltage

100

10

V

= V

REF

KA

1

Dynamic Impedance (Ω)

0.1

0.1 1 10 100

IK = 1mA

I

= 10mA

K

Frequency (kHz)

Dynamic impedance vs frequency

0

18

1.244

1.242

1.24

1.238

1.236

Reference voltage (V)

1.234

1.232

-42 -25 -10 5 20 35 50 65 80 95 110 125

Temperature (°C)

Reference voltage vs Temperature

350

300

250

200

150

100

Power dissipation (mW)

50

-40 -25 -10 -5 20 35 50 65 80 95 110 125

Ambient temperature (°C)

Power dissipation derating

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Application circuits

ZR431L

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ZR431L

Stability boundary conditions

0

0.01 0.1 1 10 100 1000 10000

5

10

15

20

25

30

Load capacitance (nF)

Cathode current (mA)

Open loop gain vs frequency

0

0 1 10 100

10

20

30

40

50

60

Frequency (kHz)

Open loop gain (dB)

Pulse response

-2.5
0 50 100 150 200 250 300 350 400 450 500

0

2.5

5

Time (μs)

Input Voltage swing (V)

0

1

2

Output voltage swing (V)

V

KA

V

IN

Single
pulse

Repetitive
pulse

Typical characteristics

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SOT23 Package outline and pad layout details

E

e

L

e1

D

A

c

E1

L1

A1

b

3 leads

mm

inches

0.8

0.031

0.9

0.035

0.95

0.037

2.0

0.079

ZR431L

Dim. Millimeters Inches Dim. Millimeters Inches

Min. Max. Min. Max. Min. Max. Min. Max.

A - 1.12 - 0.044 e1 1.90 NOM 0.075 NOM

A1 0.01 0.10 0.0004 0.004 E 2.10 2.64 0.083 0.104

b 0.30 0.50 0.012 0.020 E1 1.20 1.40 0.047 0.055

c 0.085 0.20 0.003 0.008 L 0.25 0.60 0.0098 0.0236

D 2.80 3.04 0.110 0.120 L1 0.45 0.62 0.018 0.024

e 0.95 NOM 0.037 NOM - - - - -

Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches.

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TO92 Package outline

V

Z

1

2

3

Underside view

G

ND

V

ref

ZR431L

Dim. Millimeters Inches

Min. Max. Min. Max.

A 4.32 4.95 0.170 0.195

b 0.36 0.51 0.014 0.020

E 3.30 3.94 0.130 0.155

e 2.41 2.67 0.095 0.105

e1 1.14 1.40 0.045 0.055

L 12.70 15.49 0.500 0.610

R 2.16 2.41 0.085 0.095

S1 1.14 1.52 0.045 0.060

W 0.41 0.56 0.016 0.022

D 4.45 4.95 0.175 0.195

*° 4° 6° 4° 6°

Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches

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ZR431L

Definitions
Product change

Zetex Semiconductors reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or
service. Customers are solely responsible for obtaining the latest relevant information before placing orders.

Applications disclaimer

The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for
the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is
assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights
arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract,
tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract,
opportunity or consequential loss in the use of these circuit applications, under any circumstances.

Life support

Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written
approval of the Chief Executive Officer of Zetex Semiconductors plc. As used herein:
A. Life support devices or systems are devices or systems which:

1. are intended to implant into the body

or

2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.

B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to

cause the failure of the life support device or to affect its safety or effectiveness.

Reproduction

The product specifications contained in this publication are issued to provide outline information only which (unless agreed by the
company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a
representation relating to the products or services concerned.

Terms and Conditions

All products are sold subjects to Zetex’ terms and conditions of sale, and this disclaimer (save in the event of a conflict between the two
when the terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement.
For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Zetex sales office.

Quality of product

Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer.
To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our
regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork
Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels.
ESD (Electrostatic discharge)
Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices.
The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent
of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time.
Devices suspected of being affected should be replaced.

Green compliance

Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding reg­ulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce
the use of hazardous substances and/or emissions.
All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with
WEEE and ELV directives.

Product status key:

“Preview” Future device intended for production at some point. Samples may be available
“Active” Product status recommended for new designs
“Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect
“Not recommended for new designs”
“Obsolete” Production has been discontinued

Datasheet status key:

“Draft version” This term denotes a very early datasheet version and contains highly provisional information, which

“Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance.

“Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to

Zetex sales offices

Europe

Zetex GmbH
Kustermann-park
Balanstraße 59
D-81541 München
Germany
Telefon: [phone]
Fax: [phone]
[e-mail]

© 2008 Published by Zetex Semiconductors plc

Device is still in production to support existing designs and production

may change in any manner without notice.

However, changes to the test conditions and specifications may occur, at any time and without notice.

specifications may occur, at any time and without notice.

Americas

Zetex Inc
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Hauppauge, NY 11788
USA

Telephone: [phone]
Fax: [phone]
[e-mail]

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Hong Kong

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[e-mail]

Corporate Headquarters

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Zetex Technology Park, Chadderton
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United Kingdom

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Fax: [phone]
[e-mail]

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