How did the 12-bits offset binary values be mapped to 8-bit characters in ADC12J4000EVM?

Hi Tong

The 12 bit samples are split at the 8-bit character boundaries. Here is an example showing the ADC test pattern data with the top table showing the 12 bit sample values, and the bottom table showing how these samples map into the 8 bit characters. I hope this helps make it more clear.

Best regards,

Jim B

Hi Tong

From a user standpoint this device is a single ADC. To comply with the JESD204B standard data mapping requirements, and provide an efficient implementation we use 8 logical converters. You are correct, basically we consider it as 1 converter per lane. This allows a very efficient mapping and transmission of the serial data.

Using M=1 and strictly following the JESD204B standard would result in a less efficient implementation that would consume more power and have greater data latency.

Table 12 shows how the data is mapped in the M=8 standard compliant format, with one converter per lane and 5 samples per converter per Frame. The sample labels are C#S# with C being the converter number and S being the sample number. We can consider these as 8 interleaved sub-converters, with C0 sampling earliest and C7 sampling latest.

Table 13 shows how the customer should consider the same information for an M=1 converter, with 40 samples per Frame. S# is the sample number from earliest to latest within the frame.

Best regards,

Jim B