UC2902

UC3902

SLUS232E − DECEMBER 19, 2002 − REVISED JULY 2011

LOAD SHARE CONTROLLER

1

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FEATURES

Components

Designs Incorporating Remote Output

Voltage Sensin

Compensation

APPLICATIONS

DESCRIPTION

The UC3902 load share controller is an 8-pin

device that balances the current drawn from

independent, paralleled power supplies. Load

sharing is accomplished by adjusting each

supplies’ output current to a level proportional to

the voltage on a share bus.

The master power supply, which is automatically

designated as the supply that regulates to the

highest voltage, drives the share bus with a

voltage proportional to its output current. The

UC3902 trims the output voltage of the other

paralleled supplies so that they each support their

share of the load current. Typically, each supply is

designed for the same current level although that

is not necessary for use with the UC3902. By

appropriately scaling the current sense resistor,

supplies with different output current capability

can be paralleled with each supply providing the

same percentage of their output current capability

for a particular load.

UDG−01141

1

3

2

4

8

6

7

5

+

−

R

40R

+

−

ADJ AMPLIFIER

BIAS

UVLO

+

−

+

−

+

−

SHARE SENSE AMPLIFIER

SHARE DRIVE AMPLIFIER

2.3 V

35 mV

+

0.6 V

+

CURRENT SENSE

AMPLIFIER

ERROR AMPLIFIER

GND

SENSE

ADJ

ADJR

VCC

SHARE+

SHARE−

COMP

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright © 2002 − 2008, Texas Instruments Incorporated