I am using FPGA to acquire data from LTC2122. It is a 14 bit ADC but it receives some 16 bits per channel.
No I want to extract the data bits . Please guide me which 14 bits should I consider for data and which two bits are status or the OF bits( I cant much understand from datasheet)
the ADC is working in the range of 0-5 V
You can see that the 16 bit word consists of 14 data bits, the overflow bit, and a 0 so when the FPGA decodes the serial stream that is the 16 bit word you should look for:
I don't understand what you…
The LTC2122 has a JESD204B interface, the data out lines need to go into an FPGA with a JESD204B decoder and then you can read the data. The ADC should not work with 0-5V applied, you will rail the analog input. The OF+/- pins are an overflow detection circuit that are high when the input is over ranging, it has nothing to do with the JESD204B serial stream.
Thank you Clarence I understand your point. The ADC is being read the same way you have mentioned. The input 0-5 has been railed for the input to ADC in range
I am refering to the figure 11 and figure 12 in which the word formed is 16 bits. Now I want to perform the some computation on data should I consider the MSBs or LSBs in calculation
I am confused as this is 14 bit ADC but I receive the 16 bits
I will be highly grateful for your help
I don't understand what you mean by "Now I want to perform the some computation on data should I consider the MSBs or LSBs in calculation" yes you should use all of the bits when you are doing calculations on the data.
Thank you now I got it where the overflow and the 0 bit is.
Now if I want to compare the value of 2 ADCs what I understand is that the LSB of 16 bit word that is zero should not be considered
OF is a flag that shows whether the output has overflown or not
ans the computation is to be performed on bit 2-16 of the 16 bit word
Am I right ??
Yes, the lowest 2 bits of the two words are OE and zero, they are not codes in the ADC.