Hello,
my customer uses the MSP430i2020. Following questions came up:
He uses an external reference of 1.25V.
Q1: Regarding "Table 5-21. SD24, Input Range" of the d/s the VID should be +928 to - 928 mV with gain 1. Is this value (and the other ones for different gains) valid only for internal ref? In note 2 it is stated VID = 0.8 VFSR- to 0.8 VFSR+. With ext ref of 1.25V and gain=1 this would be VID = 1.25V/1 *0.8 = 1 => + 1 to -1 V. Is the calculation right or the customer use the +928 to - 928 mV?
Q2: Is the voltage range for the AD conversion range from 0x7FFFFF (+928mV) to 0x800000 (-928mV) ?
Q3: Does the following apply?
VCC = 2.7 V and AVCC = 0V
ViA+ = 2.7V ViA- = 1.772 V = VID = FSR = +928 mV ?
ViA- = 2.7V ViA+ = 1.772 V = VID = FSR = -928 mV ?
ViA+ = 0 V ViA- = -928mV = VID = FSR = +928 mV ?
Regards, Holger