Hi Team,
Does we have any experience in 15V Vin voltage to charge 3S Battery ?
Customer is planning use 15V / 20V PD as an adapter input, But I'm not sure BQ24781 with 15Vin can support 3S battery charge or not.
If 15V can support that, how to setting ACDET ? Is an 866K + 187K resistor divider OK to use? 15*187K(866K+187K)= 2.66V is greater than 2.4V.
Thanks!
Kai
Hi Kai,
1) The VCC_SRN comparator has a maximum rising threshold of 360 mV, so VCC must be at least the battery charge voltage + 0.36 V. For a 3s application, the charge voltage is typically ~12.6 V (4.2 V/cell), so VCC should be at least 13 V. However, you also need to account for the voltage drop between the adapter and VCC (in particular, the drop across diode D1 highlighted below), and it's best to include a little extra margin just in case. All things considered, I think a 15 V adapter should be fine with a charge voltage of 12.6 V, but I would still recommend that the customer do their due diligence and verify this with their design and their adapter.
2) Your calculation is correct, and the suggested ACDET resistor divider values should be fine.
Best regards,
Angelo
