Other Parts Discussed in Thread: BQ25750
I had two questions about the BQ25756 chip:
1) On p. 68 of the datasheet there is the following line: "The battery current sense resistor between SRP and SRN is fixed at 5 mΩ; using a different value is not recommended." This is repeated on p. 24 with the statement, "It is required to use a 5-mΩ RBAT_SNS sense resistor." Why is this? I have an application where I want to set the charging current between 40 mA and 2A and a 50 mΩ resistor would allow me to do this, but the datasheet seems to forbid this, but I can't think of a reason why this shouldn't be possible.
2) On p. 57 of the datasheet it says the bit step size is 0.8 mA for IAC but 2 mA for IBAT, even though both are being measured across a 5 mΩ resistor with the same 15-bit ADC. Why are the step sizes different? Also, both of these numbers seem off since by my math the step size should be 20000 mA / 2^14 = 1.22 mA.
Thank you for your help,
Ben Smith
