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BQ51020: [BQ51020] OVP EPT's condition

Lee, Sam
Expert 6365 points

Part Number: BQ51020
Other Parts Discussed in Thread: BQ51221

Hi team,

Can you explain when OVP EPT is issued in BQ51020or the condition? According to a customer, the transmitter is intermittenly received during charging process.

Thanks,

Best Regards,

Sam Lee

  • 0
    TI__Guru* 78616 points

    Hello Sam

    The bq51020 will set the OVP fault when Voltage at RECT is 15.V ( 14.6V to 15.6V range).  At that point the bq51020 will send EPT04 (End Power Transfer 04) and turn on (ground) CLAMP1 & 2 pins to reduce voltage.  The TX will turn off when EPT04 is received.  TI TX will restart after about 40mS.

    The cause of OVP could be a RX coil or tuning of the RX coil.  The problem would probably occur during a high load to light load condition, system cannot change operating point quickly enough to reduce voltage and trips OVP.

  • 0 in reply to Bill Johns
    Expert 2490 points

    Hi~

    Is it possible to send EPT04 when voltage at RECT is under 8V?

    Could you explain about this cause?

  • 0 in reply to Mason Noh
    Expert 2490 points
    Below comment is in datasheet of bq51221. Is it apply to bq51020 equally?

    - bq51221

    Over Voltage : 0x04 : VRECT target does not converge(3)
    (3) If the voltage on the RECT pin does not reach the required value (typically 8 V) within 64 error packets
    during startup (weak coil coupling), the receiver sends EPT-OV and the transmitter will shut off.
  • 0 in reply to Mason Noh
    TI__Guru* 78616 points
    For the non-convergence condition this could be voltage is high of target or low of target, key thing to look for will be control error packets at a 30mS rate. The normal rate is 250mS.
    V-rect target voltage will change with setting of Vout and output current. 8V can be the target voltage but others are possible.