BQ25176J: how to calculate alternative value for RVset

gustavo zarba

Expert 1110 points

Part Number: BQ25176J

Hi dear people,

at the end, I am going to use the BQ25176J to charge a LIC.
The producer of the LIC recommends the following values:

ISET=750mA
Best charging voltage 3.8V.
If you cannot set 3.8V, please set 3.7V

The data sheet of the BQ25176J lists the resistors for values of:

61.9kΩ for 3.7V or
47.5kΩ for 4.05V

I interpolate a value of $57.8 k Ω to obtain 3.8V$

Is this ok, or do you have a precise formula to calculate it?

Best regards,

Gustavo

4 months ago

0 Bill Johns 4 months ago

TI__Guru 68166 points

Hi Gustavo

Sorry but this is not possible.

The BQ25176J RVset is not an analog system but a digital bin system. The Resistor value, voltage from current source is measured at start up and assigned to one of 8 bins with corresponding voltage.

0 gustavo zarba 4 months ago in reply to Bill Johns

Expert 1110 points

Hi Bill,

Thanks for the answer.

I see a trimmer (VSET-ADJ, R9) on the EVAL sluucr6. So I thought, this could be possible. What is the function of this?

Regards,

Gustavo

+1 Bill Johns 4 months ago in reply to gustavo zarba

TI__Guru 68166 points

Hi Gustavo

The VSET switch S1 will only support 8 settings and R9 is used to adjust for the settings not included in those 8.

0 gustavo zarba 4 months ago in reply to Bill Johns

Expert 1110 points

hi Bill,

I see...

So, I will be happy with the 3.7V.

Thanks and best regards!

Gustavo

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BQ25176J: how to calculate alternative value for RVset