ADVANCED 8-PIN LOAD-SHARE CONTROLLER UCC39002 UCC29002 UCC29002/1 Jan 2007

What is Load Share? What is Load Share? Provides equal distribution of the load current among parallel voltage-stabilized power supplies Why parallel supplies? High current/low voltage applications Redundancy for enhanced reliability Hot Swap capability Distributed heat removal Space and cost Jan 2007

Why would you need a Controller? Output impedance of power modules < 1mW When connected in parallel, the supply with the highest Vout will supply the majority of the output current. Because the output R is so low, it doesn’t take a large difference in Vout for this to result in large current differences. Current-limit mode increased stress = decreased reliability Jan 2007

The Concept Basic concept of load-share controller: supply a voltage feedback loop Iout of each module is accurately measured then compared to a current share bus Vout is adjusted so each module delivers an equal amount of output current Jan 2007

Improvements over the UC3902 Fully compliant with Intel SSI Specs Server System Infrastructure Power Supply and Chassis Physical dimensions, wattage ratings, electromechanical interface parameters Single connection between parallel modules Scalable load share voltage independent of Rsense High Accuracy, better than 1% at full load High-side or low-side current sense capability Hot-swap, Enable, Disconnect-at-Standby BiCMOS MSOP-8 package 5/16/2018

UCC39002, UCC29002, UCC29002/1 Start Up Logic LS driver disabled ADJ amp sinks max current Normal operation resumes when measured current >80%LS Start up logic masked out in the UCC29002/1 Jan 2007

At start up, LS driver is disabled and ADJ amp is forced to sink MAX current Starts in known state Module forced full on to engage in sharing asap Output of module adjusted high At 80% of LS, ADJ amp reverts to normal Jan 2007

UCC39002/UCC29002/ UCC290021 LS protection 5/16/2018

UCC39002/UCC29002/ UCC290021 Enable and Disconnect 5/16/2018