JAJSS91 November 2023 BQ25756E
PRODUCTION DATA
The battery regulation voltage is programmed using a resistor divider to the FB pin. The default internal voltage reference is 1.536 V, and can be changed via the VFB_REG register bits. The top of the resistor divider is selected to be 249 kΩ.
RTOP = 249 kΩ
The bottom resistor can be calculated as:
where
RFB_BOT = 25.09 kΩ.
Choosing the nearest 0.1% resistor value, gives RFB_BOT = 24.88 kΩ, for a nominal charge voltage of 16.89 V. Further fine-tuning of the regulation voltage can be achieved by changing the internal feedback reference. For example, to get the regulation voltage to exactly 16.8 V with the selected resistor divider, the internal voltage reference could be changed to 1.528 V via VFB_REG.
It is recommended to use 0.1% accurate resistors to maximize the charge voltage accuracy.