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BQ25898C: PMI8952+BQ25898C can't get 6~7V for QC 3.0

Part Number: BQ25898C
Other Parts Discussed in Thread: BQ25890, BQ25890H

Hi Team,

My customer is using PMI8952 + BQ25898C for QC 3.0.

It works fine with QC 2.0, but for 3.0, the voltage direct up to 9V, can't get 6~7V voltage. If remove the BQ part, the stable charging power is 6.8V.

Because we don't have software source code, could you please help to give some hint to debug?

Thanks a lot for support,

Kevin Dang

  • Kevin,

    bq25898C does not have D+/D- and should not any influence over adapter voltage. What is PSEL voltage level? If PSEL=low then input current limit is 1.5A. Charging is default disabled on the 898C. When charging is enabled, can the adapter provide 1.5A plus whatever the PMI8952 draws without voltage drop?
  • Hi Jeff,

    The adaptor can provide 3A without voltage drop. The PSEL pull to low.

    Do you know who has already use this for QC 3.0?

    Do you mean the PMIC needs to control this aux charger by GPIO?

    Thanks a lot,

    Kevin Dang

  • Hello Kevin,

    Can you please elaborate on how the customer is performing the handshaking with the QC2.0/3.0 adapter? I'm assuming the host is taking care of the handshaking.

    Like Jeff mentioned, the 898C doesn't have D+/D- lines which are used to perform the handshake with the adapter to negotiate a higher output adapter voltage. The PSEL only affects input current limit. Could the QC3.0 adapter have a different output impedance than the QC2.0?

    We have devices that do handshaking with HVDCP adapters, such as QC2.0, like the bq25890 and bq25890H, but these use the D+/D- lines for this.