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bq25504 problem

Luke Morton
Prodigy 50 points
Other Parts Discussed in Thread: BQ25504

Hi

I have the following circuit for the bq25504, operating under the conditions used in the datasheet:

I have simulated this circuit with pSPICE and it works fine. However, upon building it on a breadboard (I have used an adapter for the chip), nothing happens upon applying an input voltage from a DC power supply. Is there a reason for this, or is it likely that the chip has not been soldered into the adapter correctly? Is it also possible that the chip has been damaged by the heat gun used to solder it?

Thanks for your help.

  • 0
    TI__Genius 12485 points

    Luke,

    What is the voltage input you are applying? 

    With heat and flux, you are probably corrupting the resistor dividers. Can you clean the board of any flux residue and retry? You could also knock the resistors off by a factor and check if it works.

    Regards,

    gautham

  • 0 in reply to Gautham
    Prodigy 50 points

    Hi Gautham

    The voltage input is ranging from 0.5-1V.

    What would be the expected effect of the resistor dividers being corrupted? With Vin = 1V, I'm getting VBAT_OV = 380mV, VBAT_UV = 340mV and VRDIV = 850mV. This problem persists even if I divide my 4 resistance values by 10.

    Could there be a problem with the fact that I've connected OK_HYS and OK_PROG to ground? This wasn't a problem in simulation, but could that be the cause?

    Also, just in case it helps, Upon applying the input, VSTOR and VBAT both ring a little (but around the 0V point). This ringing is at roughly 750kHz, and has a peak value of 200mV (for VBAT) and 125mV (for VSTOR) with a 1V input.

    Lastly, I have been unable to reproduce this, but one time when I was applying the input, the voltage on VSTOR actually was charging and discharging - between about 2 and 1.25V, over a period of about 10 seconds (I wasn't able to measure it at the time, and have since not seen the issue again). Could this be significant?

    Thank you for your help.