I checked AD7190 datasheet's gain. Why 001 and 010 was reserved? It can not be
set *2 and *4? Please help to clarify it and thanks a lot in advance!
The AD7190 has gains of 1, 8, 16, 32, 64 and 128 only. The options 001 and 010
are reserved. These options select a gain of 2 and 4. However, the AD7190 does
not meet the datasheet specs when the gain bits are set to 001 and 010 - the
INL degrades. So, a customer should not use the AD7190 with the PGA bits set to
001 or 010. We do not guarantee any specifications when the PGA bits are set to
001 or 010.