BQ25170: Custom end charge voltage

Alexandru Burcea

Part Number: BQ25170

Tool/software:

Hi,

I designed a charger with a digital potentiometer connected to the VSET pin. The datasheet provides a table with discrete resistance and end charge voltage values.

The voltage variation with the resistance is not quite linear, so how do I obtain an end charge voltage that is not in the table?

I am aware that the VSET resistor is read at startup and I included a MOSFET to repower the chip.

5 months ago

0 Bill Johns 5 months ago

TI__Guru 74146 points

Hi Alexandru

Only the VSET values listed in the table are available and only the resistor values listed in the table are recommended.

VSET is more of a digital circuit. The voltage measured on resistor at startup will correspond to one of the bins with a voltage assigned to it.

We have not tested with a digital potentiometer only fixed resistors, you will need to evaluate this to determine if it give you expected performance.

0 Alexandru Burcea 5 months ago in reply to Bill Johns

Prodigy 80 points

Thank you for the answer, I will set the digital potentiometer to one of the values in the table.

There remains a question, what happens if the resistance value is between two values from the table?

+1 Bill Johns 5 months ago in reply to Alexandru Burcea

TI__Guru 74146 points

Hi Alexandru

Alexandru Burcea said:
There remains a question, what happens if the resistance value is between two values from the table?

If the resistor is between two recommended values output voltage could switch to higher or value listed in table.

The VSET resistor does not behave like a voltage divider and generate an intermediate value.

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BQ25170: Custom end charge voltage