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hamming noises from bq500211

or sam
Expert 2020 points
Other Parts Discussed in Thread: BQ51013, BQ500211, TPS81256

Hi

I am using bq500211 with bq51013.

1.I am using evl and when I raise the bq51013 from the bq500211  I am hearing a nois like a shortcut. I guss it is because the current gets high but does this sound should be or it should stop transmitting before?

2. when I connect the bq500211 to a li-ion battery (I want to activate the base unit from battery) via tps81256 same noise happen after few min and after few sec  d4 led becomes red and it stop transmitting. (the battery is not empty I see it the voltage on  is 5V but the current  from the battery rises fro 0.3 to 0.5 amper few sec before it stops so I think both phenomenas related )

why is it happening?

addition info -  when I connect power supply - 3.7V instead of battery it is working properly.

thanks in advanced 

  • 0
    TI__Guru* 75856 points

    Does the Hamming Noise you describe sound like the one heard in post “ Audible Noise from BQ500410AEVM-085” ?

    e2e.ti.com/support/power_management/wireless_power/f/693/t/278092.aspx

  • 0 in reply to Bill Johns
    Expert 2020 points

    Hi thanks,

    Yes this is probably the same noise.

    in my evl system its happens only when currents gets bigger than ~0.5 from the power supply to the bq500211 evl.

    my question is why does this happens when I use battery (after few minutes) and not when I use power supply.

    both power supply and battery are 3.7V and are connected to the bq50211 via tps81256 (one at a time - not together)? why doent the bq500211 act the same for baterry and power supply with same voltage?

    why does after few minutes the current through the battery clime to 0.5 amp (without changing the position of the coils)? 

    thanks in advanced,

  • 0 in reply to or sam
    TI__Guru* 75856 points

    The bq500211 is a 5V input EVM at full output power the input current can be up to 1.5A.  Care should be taken to make sure voltage drop in leads and connections between EVM and Power Supply are very low.  Good connections and larger leads are needed.

    Also a large decoupling capacitor at the input to EVM will help reduce ripple and voltage drop due to transients.

     

    The TPS81256 is a boost convert that you are using to provide 5V from a battery, 3.7V converted to 5V.

    A similar problem will occur between the battery or power supply and TPS81256. Voltage drop between the power source and boost convert can present problems.

     

    The Audio Noise is due to voltage changing on the bulk input capacitors, reducing the voltage change on the capacitors will reduce the noise.