LTC4015 Ready to charge but Charge suspended

We have a new design, with a ESP32 controlling an LTC4015. Everything seems to be ok, it says Ready to charge, but then Charge suspended. Could someone have a look at the PCB design to see if I made some mistake? It's a KiCad design. Please tell me where to send Gerber files or what you need? Thnx in advance!

  • Thank you very much, we will returen with feedback on lessons from our update design

  • A quick update - we discovered we had actually left out a decoupling cap for INTVCC which must have gotten removed in some revision (it was present in earlier versions) which caused our 4 layer board to misbehave, but with this in place it works well.

    The 2-layer version did not seem to work even with this cap added. For this reason we ended up with a 4 layer board which works well in nearly all respects, except for measurement of IBAT and the coulomb-counter.

    The IIN seems to be pegged at 32768 with a battery connected, and the coulomb counter counts down really quickly until it reaches 0.

    My current working theory that one of the CSP/CSN inputs get damaged during battery connection as I have tried a couple of chips, and they seem to both exhibit the same problem.

    In the specs CSP/CSN is specified with a max difference of 50mV - do you know if exceeding this causes damage to the chip? Do you have any tips for avoiding this?

    •  Analog Employees 
    on Aug 25, 2020 7:22 PM 4 months ago in reply to Preben

    Hi Preben,

    The abs max differential voltage for those pins is +/- 0.3V. Exceeding 50mV is not a problem.

    It is possible that the IC was damaged due to inrush current through the sense resistor, but then a fresh IC would work.

    Make sure the coulomb counter is configured correctly and check the CCREFP/CCREFM pins, etc.

    Regards,

    Zack

  • Having soldered up a triplet of new boards, I've pretty much confirmed that the IC's had inrush damage - the new ones all work. I will do some aggressive testing on them and see if I can replicate the problem, but the two original chips with a problem had all been through a few solder cycles and some prototyping harassment, so I'm optimistic I won't have the problem going forward.

    Thank you for the help, we are very pleased to have a well functioning board that will shortly go into production:)

    •  Analog Employees 
    on Aug 31, 2020 10:24 PM 4 months ago in reply to Preben

    Hi Preben,

    That's great to hear! Hope all goes well for you moving forward.

    Regards,

    Zack