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Original question:

BQ25792EVM: Charger status reg, fault status with voltage applied

BQ25792EVM: "Not Qualified Source" shown in the VBus_Stat register

Nakka Malesh
Prodigy 130 points
Part Number: BQ25792EVM

Hi,

     Thanks for your answer.

My input voltage is 20.6V

when i write EN_HIZ=0, the source was qualified (poor_src=0) now my charger status reg0 is 0x0D

i have a resistance of 10M ohm between power source and ACx FET, Is it a problem?

I have observed the voltage Vbus through oscilloscope is 20.6V.

My Doubts:

Q1) I have observed that Vbus_stat is shown that "not qualified source(0x8)" ,is it a cause for converter prevention?.

Q2) when i want to read the data from charger, should i need to reset the registers through RST bit?

Q3) Is BC1.2_DONE bit should be HIGH to run the Converter?

Q4) voltage at ILIM_HIZ is 1.23V ,from this IINDPM should be 230mA but the register value is at its default value 300mA why?

Q5) Please tell me why the converter not working even EN_HIZ=0?

Please reply me

Best Regards

Malesh Nakka

  • 0
    TI__Guru**** 166686 points

    Hi Malesh,

    If the 10Mohm resistor is in series between the power source and the ACFET, then that is what is causing the poor source fault.  Please short that resistor and try again.  If the converter tries to pull even 1mA current from the power source, the V=IR drop results in the voltage at VBUS being very small.

    Regarding 1, no.  That means that the D+/D- detection did not find a power source that is can communicate with and so sets IINDPM to the default value of 3A.

    Regarding 2, no.  The reset start in default state.

    Regarding 3, no.  See 1 above.

    Regarding 4, the conversion from ILIM_HIZ voltage to register is not exact.

    Regarding 5, it is because of the 10Mohm resistor.

    Regards,

    Jeff