Datasheet

  
  

SLUS165C – MARCH 1999 - REVISED JANUARY 2002
1
www.ti.com
FEATURES
D
Fully Differential High Impedance Voltage
Sensing
D Accurate Current Amplifier for Precise
Current Sharing
D Opto Coupler Driving Capability
D 1.25% Trimmed Reference
D Master Status Indication
D 4.5-V to 35-V Operation
DESCRIPTION
The UCx907 family of load share controller ICs provides all the necessary features to allow
multiple-independent-power modules to be paralleled such that each module supplies only its proportionate share
to total-load current.
This sharing is accomplished by controlling each module’s power stage with a command generated from a
voltage-feedback amplifier whose reference can be independently adjusted in response to a common-share-bus
voltage. By monitoring the current from each module, the current share bus circuitry determines which paralleled
module would normally have the highest output current and, with the designation of this unit as the master, adjusts
all the other modules to increase their output current to within 2.5% of that of the master.
The current share bus signal interconnecting all the paralleled modules is a low-impedance, noise-insensitive line
which will not interfere with allowing each module to act independently should the bus become open or shorted to
ground. The UC3907 controller will reside on the output side of each power module and its overall function is to supply
a voltage feedback loop. The specific architecture of the power stage is unimportant. Either switching or linear designs
may be utilized and the control signal may be either directly coupled or isolated though the use of an optocoupler or
other isolated medium.
Other features of the UC3907 include 1.25% accurate reference: a low-loss, fixed-gain current-sense amplifier, a fully
differential, high-impedance voltage sensing capability, and a status indicator to designate which module is
performing as master.
Copyright  2000, Texas Instruments Incorporated        
         
       
   
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
C/S OUT
C/S (+)
C/S (–)
(–) SENSE
POWER RETURN
ARTIFICIAL GND
VREF
ISET
STATUS INDICATE
CURRENT SHARE BUS
ADJ OUT
ADJ INPUT
COMP
(+) SENSE
VCC
OPTO DRIVE
DIL-16 J or N PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
C/S OUT
C/S (+)
C/S (–)
(–) SENSE
POWER RETURN
ARTIFICIAL GND
VREF
ISET
STATUS INDICATE
CURRENT SHARE BUS
ADJ OUT
ADJ INPUT
COMP
(+) SENSE
VCC
OPTO DRIVE
SOIC-16 DW PACKAGE
(TOP VIEW)
1920132
17
18
16
15
14
1312119 10
5
4
6
7
8
ADJ OUT
ADJ INPUT
N/C
COMP
(+) SENSE
C/S (–)
(–) SENSE
N/C
POWER RETURN
ARTIFICIAL GND
C/S (+) C/S OUT N/C STATUS INDICATE CURRENT SHARE BUS
ISET
N/C
OPTO DRIVE
VCC
VREF
PLCC-20, LCC-20,
Q OR L PACKAGE
(TOP VIEW)