Datasheet SC4431CSK-0.5TR, SC4431CSK-1TR, SC4431CSK-2TR Datasheet (Semtech Corporation)

SHUNT REGULATOR WITH OPEN
COLLECTOR OR OUTPUT

SC4431

PRELIMINARY - September 11, 2000

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DESCRIPTION

The SC4431 is a four terminal device for regulating an
isolated power supply with very low output voltage.

It is intended to be used as a replacement for three ter­minal shunt regulators such as SC431L where the out­put voltage is too low for them to function in conjunc­tion with an opto-isolator. It achieves this by having
seperate supply and output pins, allowing the output to
sink current at voltages as low as 0.2V, while the sup­ply pin still has sufficient voltage for the device to func­tion. In this way, allowing for a 1.6V drop through an
opto-isolator diode, regulation down to 1.8V out can be
achieved.

The SC4431 shunt regulator is available with three ini­tial reference voltage accuracies (0.5%, 1.0% and

2.0%) in the space saving 5-lead SOT-23 package.
The three voltage tolerances allow the designer the
opportunity to select the proper cost/tolerance for their
application.

TYPICAL APPLICATION CIRCUIT

FEATURES

•= Trimmed bandgap design - initial accuracies to

0.5%

+

•= 40mA drive capability

•= Wide supply voltage range - 1.5V to 15V

•= Low supply current - typically 110µA

•= Full industrial temperature range

APPLICATIONS

•= Opto driver for very low output voltage isolated

power supplies

ORDERING INFORMATION

Part Number

SC4431CSK-X.TR SOT-23-5

Notes:
(1) Where “-X” denotes initial reference voltage toler­ance. Available options are ±0.5% (-.5), ±1% (-1) and
±2% (-2).
(2) Only available in tape and reel packaging. A reel
contains 3000 devices.

(1)(2)

Package

VIN

Primary Side
Controller

T1

Secondary Side
Rectification
and Filtering

R1

U1

4N25

R2

5.1k

U2 SC4431

C2
22nF

1

VCC

GND

2

2V OUT

C1

33nF

45

REFOUT

3

NC

R3

6.34k

R4
10k

2V Output Isolated Power Supply

1

© 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320

SHUNT REGULATOR WITH OPEN

SC4431

COLLECTOR OR OUTPUT

PRELIMINARY - September 11, 2000

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Maximum Units

Input Supply Voltage V
Output Voltage V
Reference Voltage V
Continuous Output Current I
Reference Input Current I
Operating Ambient Temperature Range T

Operating Junction Temperature Range T
Storage Temperature Range T
Thermal Impedance Junction to Ambient
Thermal Impedance Junction to Case
Power Dissipation at T

= 25°C P

A

θ

Lead Temperature (Soldering) 10 seconds T

CC

OUT

REF

OUT

REF

STG

θ

JA

JC

LEAD

A

J

D

-0.5 to +16 V

-0.5 to V

CC

V

-0.5 to +4 V
40 mA

5mA

-40 to +85 °C

-40 to +150 °C

-65 to +150 °C
256 °C/W

81 °C/W
475 mW
300 °C

ESD Rating (Human Body Model) ESD 2 kV

ELECTRICAL CHARACTERISTICS

Unless specified, TA = 25°C, VCC = 2V, I

Parameter Symbol Test Conditions MIN TYP MAX Units
VCC

= 2mA. Values in bold apply over ful l operating temperature range.

OUT

Input Supply Voltage V
Input Supply Current I
Off State Input Supply Current I

CC(OFF)

REF

Reference Voltage V

Change in V
in V

CC

Change in V
in I

OUT

due to change VCC = 1.5V to 15V 8 15 mV

REF

due to change I

REF

dV

dV

dV

dI

CC

CC

REF

REF

CC

REF

OUT

1.5 15

V

REF

V

= 1.187V, V

REF

SC4431-.5, V

= V

OUT

= 2V 65 100 µA

OUT

REF

= V

OUT

1.219 1.224 1.231 V

110

1.207 1.243

SC4431-1, V

REF

= V

OUT

1.212 1.224 1.236 V

1.200 1.250

SC4431-2, V

REF

= V

OUT

1.200 1.224 1.250 V

1.187 1.261

= 0.1mA to 40mA 8 28 mV

OUT

200

150

20

36

V

µA

2

© 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320

SHUNT REGULATOR WITH OPEN

SC4431

COLLECTOR OR OUTPUT

PRELIMINARY - September 11, 2000

ELECTRICAL CHARACTERISTICS (Cont.)

Unless specified, TA = 25°C, VCC = 2V, I

Parameter Symbol Test Conditions MIN TYP MAX Units
REF (Cont.)

= 2mA. Values in bold apply over ful l operating temperature range.

OUT

Reference Input Current I

OUT

Saturation Voltage V

Off State Output Current I

OUT(OFF)

REF

OUT(SAT)

0.1mA ≤ I

I

= 5mA, ICC = 500µA 50 75 mV

OUT

V

= 1.261V, I

REF

V

= 1.187V, V

REF

≤ 10mA

OUT

= 40mA 275 300 mV

OUT

= 2V 0.5 1 µA

OUT

0.3 0.5 µA

1.0

100

400

10

3

© 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320

PRELIMINARY - September 11, 2000

BLOCK DIAGRAM

SHUNT REGULATOR WITH OPEN
COLLECTOR OR OUTPUT

SC4431

PIN CONFIGURATION

SOT-23 -5 Lead (Top View)

PIN DESCRIPTION

Pin Pin Name Pin Function

1 VCC This is the input supply pin for the IC.
2 GND Logic and power ground.
3 NC No connection.
4 REF This is connected to the non-inverting input of the error amplifier.
5 OUT This is the output pin of the device, essentially an open collector.

4

© 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320

PRELIMINARY - September 11, 2000

DEVICE OUTLINE - SOT-23-5

SHUNT REGULATOR WITH OPEN
COLLECTOR OR OUTPUT

SC4431

LAND PATTERN - SOT-23-5

ECN 00-1315

5

© 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320