This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ500511: bq50002+bq500511 indicates error but not EPT code showing

Part Number: BQ500511
Other Parts Discussed in Thread: BQ50002A, BQ50002


I have a 5W design based on the bq50002+bq500511 with the design itself based almost identically on the reference design of TI - other than a few board size changes. 

With the latest test batch of boards we found we would get an error indication ( RED LED indicated on board ). When I checked the EPT code it comes back 00 which I believe means unknown error. It shuts down all charging, waits 5 minutes and then starts up again. 

I have checked the voltage rails going into the design and everything looks fine. Absolute worst case I get 200mV drop on a 5.1V input. 

It seems to happen when the charging coil - Wurth coil 760308100111 is approx. 6mm away or there abouts from a phone. We have reproduced this with Samsung S8, Samsung S7, Samsung S6, Samsung S5 with 3rd party back cover, Apple iphone 6 with 3rd party back cover. 

With the fault condition not happening for hours at a time it is difficult to fault find and with no EPT code I am not sure what other information I can extract to understand the fault? 

Any help would be appreciated. 



  • Hi Trevor
    Double check if you are using bq50002 / 511 or bq50002A / 511A. Devices cannot be mixed and the non-A should not be available.

    What is the FOD loss running on the unit?
  • Hi Bill

    Thanks for the reply. We are moving across to the A parts but this run was with the non A parts.

    I would need to get everything hooked up again to measure the FOD. Is there are good range to be within? If it was a problem with FOD this would show itself more clearly with a flashing red led?

  • The FOD Loss (Calculated Parasitic Loss) should be a negative number, if it is positive you have some risk of tripping FOD.
    Yes if FOD fault is tripped then red led is flashing before fault trips.

    Another test could be increasing FOD Threshold to a large value, if the problem is resolved it indicates FOD performance issue.
  • Typical values I remember seeing before were -400 and -700 so I am good there.

    My problem is that the red light comes on so infrequently that it is difficult to say a problem is completely resolved without leaving on test for many many hours. I need to understand if any parts of the design are borderline failure. For example, like you suggested if the FOD had been positive there might be a probem.

    Also when the RED led comes on, is there information I can extract to give me more understanding of where the problem is because the chipset deteceted a fault so I was hoping it would give me some idea of why it entered a fault condition. The EPT code was 0?
  • If the unit restarts 5 min after shutdown it would be FOD, Overtemp RX or Overtemp TX.
    EPT 00 is "EPT Unknown" the RX is commanding TX shutdown but not saying what is wrong. BUT this should be an immediate restart (40ms) not 5 min.