Team,
My customer has designed in the BQ76PL455A, and they have the following question:
I’m finally getting to finalizing the register values for the BQ part and have a question about the cap selection.
In the datasheet, the recommended cap value for OUT1/2 is 390pf for 60us sampling with 8 oversamples @ 12.6us each. In the eval doc, there’s a table (see below figure) that provides recommendation for single cycle sample:
It seems that there’s some derating of necessary capacitance for the additional oversampling.
Based on the RC time constant of the table above, it seems that the conversion period is being held beyond what’s necessary for ¼ lsb. Can you give me any guidance as to how I would calculate the default values? --- I’m trying to understand the tradeoffs. Sample time vs number of over sampling vs capacitance. Or is this one of those cases that testing will really indicate what’s better?
Thanks,
Brian
