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TPS65400 - PGOOD status when current sharing or one switch OFF

Eric HEURTEL
Prodigy 130 points
Other Parts Discussed in Thread: TPS65400

Hello,

I want to use the TPS65400 *without programming* (only default values).

If I understand the DS, by default PGOOD output is the logical AND of individual PGOODs.

It's not clear if individual PGOOD is automatically masked when an output is disabled (ENSWx=0) : will PGOOD pin be asserted (tristated) when using for example only three channels ? If not, what is the solution to have PGOOD asserted when all *ACTIVE* outputs are OK, and without programming ?

Independantly, in case of Current Sharing, it seems that slave individual PGOOD is not masked so PGOOD pin will never be asserted when using this mode, right ? So, same question, how can I get PGOOD asserted when using current sharing, and without programming ?

Proposition : what if I connect VFB of an inactive or slave channel to the VFB of an active or master channel, will the individual PGOOD be OK so that the global PGOOD will be asserted ?

Thanks in advance

  • 0
    TI__Intellectual 2590 points

    Defualt PGOOD output is the logical AND, if you just use three channels, and put ENSWx=0, PGOOD asserted high when all atvice outputs are ok.

    if you use current sharing, need to mask the slave channel's pgood signal. otherwise, PGOOD will asserts low.

    the slave channel's FB will not have any function if you use current sharing mode, so you method will not change PGOOD's status.

    thanks!

  • 0 in reply to Eric Guo1
    Prodigy 130 points
    Thank you for answering. Anyway it's not what I observe : PGOOD is asserted when having four outputs enable (all pins ENSWx are floating), but PGOOD goes low when one output is disabled (with one ENSWx pin tied low, ENSW1 in my case).
  • 0 in reply to Eric HEURTEL
    TI__Intellectual 2590 points
    Hi Eric,

    i have duplulicated your result in lab, the reuslt is same with you.
    however, i don't have any method to improvde this in hardware, if you can mask the PG signal internally, using PMbus to mask enable off channel's PG, it will not influecne total PG function.
    thanks!