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UCC39002: UCC39002 Application Question

Cao Cao
Intellectual 770 points
Part Number: UCC39002
Other Parts Discussed in Thread: UCC29002

Hi Sir,

I plan use UCC39002 application PSU parallel. But have some question need you help.

In normal parallel PSU priority first is high voltage, so UCC39002 monitor CS+/CS- by LS line ask Low voltage PSU sink more current let CS+/CS- voltage increase by modify RF48 change ADJ.

DS show sink current MAX is 6mA, so RF48 modify 510 ohm let 2 PSU same load sharing, but current is different.
Modify RF48 750 ohm again and Current just same.

May I know UCC39002 sink current really have 6mA? Or is my understand error?

  • 0
    TI__Intellectual 2230 points
    Yes, the adjust pin sink current will not exceed its 6 mA maximum as determined by the internal 500-Ω emitter resistor and 3-V clamp of EAO.
  • 0 in reply to Oliver Pan91
    Intellectual 770 points

    Hi Oliver,

    Also, whether ADJ pin regardless of the current detection is the number of current, will sink current action?
    Because I use 54V rail to parallel, Load 0A, the output voltage will be up to 59.8V (Figure 1).
    if I decrees the external resistance the output voltage will down (Figure 2).

  • 0 in reply to Cao Cao
    TI__Intellectual 2230 points
    Hi Cao,

    The UCC29002 compares the average per module current level to the output current of the respective module. If the average per module current, represented by the load share bus is higher than the module’s own output current, an error signal will be developed at EAO. The error signal is than used by sinking a current(IADJ) to make the necessary output voltage adjustments to ensure equal output currents among the parallel operated power supplies.

    Thanks
    Oliver