SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
The data filter is a configurable Sinc filter which supports the following filter types: Sinc1, Sinc2, Sinc3, and SincFast. The data filter OSR (DOSR) settings can be configured from 1 to 256 and is independent of the comparator filter. Effective resolution of the data filter (ENOB) depends upon Data filter type, DOSR, and sigma-delta modulator frequency. By default, the data filter is disabled and setting of SDDFPARMx.FEN = 1 enables the data filter. The data filter output is represented in 25-bit signed integer in two’s complement format. This filter unit translates a low input signal as ‘-1’ and a high input signal as ‘1’. The resulting calculation gives both positive and negative values for the output of the data filter. Table 13-3 shows the different full scale values that the data filter can store using different OSRs.
See Section 13.4.1 to understand how to calculate data rate and latency of data filter.
DOSR | Sinc1 | Sinc2 | Sinc3 | SincFast |
---|---|---|---|---|
x | x | x2 | x3 | 2x2 |
4 | –4 to 4 | –16 to 16 | –64 to 64 | –32 to 32 |
8 | –8 to 8 | –64 to 64 | –512 to 512 | –128 to 128 |
16 | –16 to 16 | –256 to 256 | –4096 to 4096 | –512 to 512 |
32 | –32 to 32 | –1024 to 1024 | –32,768 to 32,768 | –2048 to 2048 |
64 | –64 to 64 | –4096 to 4096 | –262,144 to 262,144 | –8192 to 8192 |
128 | –128 to 128 | –16,384 to 16,384 | –2,097,152 to 2,097,152 | –32,768 to 32,768 |
256 | –256 to 256 | –65,536 to 65,536 | –16,777,216 to 16,777,216 | –131,072 to 131,072 |