I have three questions regarding the ADC in the TMS320C5505A. I have read the relevant parts of SPRS660F (Sept 2013) and SPRUFP1C (Jan 2012).
My application: measuring external battery voltage using channel 1, and other internal signals using channels 3,4 and 5.
Question 1: Regarding the offset on each ADC channel:
The data sheet specifies a maximum offset of 2 LSB for the ADC.
Is the offset the same on all channels ?
In other words, when we measure the offset using channel 0 (according to the procedure in section 2.4 of SPRUFP1C), can we subtract this offset from all the ADC channels, to improve their accuracy ?
Question 2: referring to figure 2 in SPRUFP1C : what is the tolerance of the division ratio of the channel 1 voltage divider (nominally 1/8) ? (I cannot find this in the data sheet.)
Question 3: referring to figure 2 in SPRUFP1C : what is the tolerance of the impedance to ground at GPAIN0 when GNDON is on (nominally 280k + 40k)? (I cannot find this in the data sheet.)
Thanks,
Neil.