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TPS25944A: Overload does not auto-retry but latch off

Arnaud Puret
Prodigy 80 points
Part Number: TPS25944A
Other Parts Discussed in Thread: TPS25944L

Hi,

I have an eFuse TPS25944A (the auto-retry version, reference confirmed with the device marking) which controls a power path (see schematic below):

  • Vin = 5 V;
  • Ilim = 2.16 A (Rlim = 41.2 kOhm);
  • UVLO / OVP resistors;
  • Cdvdt = 1 nF;
  • Cout = 1uF.

The eFuse works as expected in normal condition but when an overload occurs (tested with Iout=2.5 A < Ifastrip), the output is latched off and no auto-retry is done. Then, the device do not switch on the output when the load falls below Ilim. It seems to me this is approximately the TPS25944L behavior, the TPS25944A should auto-retry according to its datasheet and the figure 43:

Can somebody explains me where is my mistake(s)?

Thanks !

Best regards,

Arnaud Puret

  • 0
    TI__Guru** 105361 points

    Hi Arnaud,

    Thanks for reaching out!

    Your UVLO, OVP thresholds are close to nominal VIN. Can you check whether the device is still in UVLO or OVP events ? Can you remove R12 and test again.

    Please share Vin, Vout, Input current and FLTb test waveforms

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 80 points

    Hi Rakesh,

    Thanks for your quick answer.

    I think UVLO/OVP are not the problem: the same board contains 3 other eFuses which don't auto-retry after overload (same problem). They control +12V power paths with more larger thresholds: UVLO = 8 V, OVP = 15 V. Their schematic is below (an input reverse polarity protection is present. Do not mind the peculiar usage of PGTH).

    It is simpler to test the +12V eFuse. I can't graph any current for now but the others waveforms are here:

    I triple checked the device marking but it seems to be a TPS25944A...:

    May these informations help to understand the problem...

    Best regards,

    Arnaud Puret

  • 0 in reply to Arnaud Puret
    TI__Guru** 105361 points

    Hi Arnaud,

    Thanks. This is good information. 

    Do you have local TI sales contact to submit the units for FA and rootcause. ? By any chance do you have TI EVM to cross the behavior and confirm ?

    All the parts you received are behaving the same way - right ?

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 80 points

    Hi Rakesh,

    I have no contact with TI sales and I don't know what are FA and rootcause. And, no, I haven't TI EVM right now...

    All the parts was bought and mounted by our EMS (10 prototypes for now and 500 upcoming boards with 5 eFuses each). I can confirm the problem for 4 eFuses per board (the last one is more difficult to test).  

    Best regards,

    Arnaud Puret

  • 0 in reply to Arnaud Puret
    TI__Guru** 105361 points

    Hi Arnaud,

    ok. Before taking next step, can you include probed current in the above test waveform and share for review

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 80 points

    Hi Rakesh,

    Here are the requested waveforms: they show Vout and Iin. The first has the same scales than the waveforms from my previous post. The second displays time/voltage/current cursors.

    Do not mind the current value precision: it isn't exactly the eFuse input current but the board current, a small offset was recorded.

    May this help !

    Best regards,

    Arnaud Puret

  • 0 in reply to Arnaud Puret
    TI__Guru** 105361 points

    Hi Arnaud,

    Thanks.

    It is showing TPS25944L (latch version) behavior. Where did you bought these units? from distributor ?

    I will send you private message. Please reply to take next steps and check the materail.

    Best Regards,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 80 points

    Hi Rakesh,

    Thanks a lot. I will email you as soon as I receive all the buying information from my EMS.

    Best regards,

    Arnaud Puret

  • +1 in reply to Arnaud Puret
    TI__Guru** 105361 points

    Hi Arnaud,

    I have received your email and will follow-up on the same.

    I am closing this thread here for records.

    Best Regards,

    Rakesh