Hi,
first off all thanks to all for the fast response.
The ADS is unipolar supplied by a + 3,3V Reference and works fine with our applied test signals (we want to amplify small signals of a low voltagge source (like a TC or something else) and apllied the Vbias voltage to the differential ADC Input pair.. The problem is that the PGA setting is like following:
MCU --> ADS1248;
PGA setting MCU: 1 --> PGA setting ADS: 1
PGA setting MCU: 2 --> PGA setting ADS: something wrong
PGA setting MCU: 4 --> PGA setting ADS: something wrong
PGA setting MCU: 8 --> PGA setting ADS: something wrong
PGA setting MCU: 16 --> PGA setting ADS: something wrong
PGA setting MCU: 32--> PGA setting ADS: 2
PGA setting MCU: 64 --> PGA setting ADS: 4
PGA setting MCU: 128 --> PGA setting ADS: 8
Again, all transmitted data is controlled by a logic analyzer and sends the correct values for the register. It seems that the ADS get a bit loss in the first of the three PGA bits...
I hope i could precicise our problem.
Regards Timo