Using the BQ24630, I want to charge a pack as fast as possible, guaranteeing that I won’t exceed a charge current of 4.2A. I want to make sure that with the tolerances of the part, and external part tolerances, that this limit is not exceeded.
The following discussion assumes the EVM schematic and Reference Designators.
I’ve put together a spreadsheet that calculates the Charge Current range based on specs of the part, and tolerances of various components. I was looking for a little guidance to make sure I calculated things correctly, and have interpreted what is and is not included in the line item specs in the datasheet.
I calculate the range of output voltages on Vref based on the datasheet.
I use the tolerances on the resistors (R11 & R12) used to determine ISET 1, and calculate a range for the ISET 1 voltage.
I then use the Charge Gain from the Electrical Characteristics, and apply the Charge Tolerance given in the datasheet to the Gain term.
Last I apply the tolerance of the Current Sense resistor in the Charge path, R18.
This gives me a range of output currents.
I have attached my spreadsheet, where I make the calculations above, and look at the effect of using 0.1% resistor for R11 & R12, attempting to keep the maximum value under 4.2A.
Have I made errors in my calculations, or misinterpreted what is in the BQ24630 Electrical Characteristics?
Thanks!
