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.
A differential line is used for the share bus to maximize noise immunity and accommodate different voltage drops in each power converter’s ground return line. Trimming of each converter’s output voltage is accomplished by injecting a small current into the output voltage sense line, which requires a small resistance (typically 20 Ω to 100 Ω) to be inserted.
| Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | Load Share Controllers datasheet (Rev. E) | 28 Jul 2011 | |
| User guide | UCC39002 Advanced Load-Share Controller User's Guide, HPA027A (Rev. A) | 09 Feb 2004 | ||
| Application note | U-163 The UC3902 Load Share Controller and its Performance in Distributed Power (Rev. A) | 13 Dec 2002 | ||
| Application note | U-129 UC3907 Load Share IC Simplifies Parallel Power Supply Design | 05 Sep 1999 |
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The UCC39002 is an advanced, high-performance load-share controller that provides all the necessary functions to parallel multiple independent power supplies or dc-to-dc modules. This load-share circuit is based upon the automatic master/slave architecture utilized in the UC3902 and UC3907 (...)
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| PDIP (P) | 8 | Ultra Librarian |
| SOIC (D) | 8 | Ultra Librarian |
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