JAJSLQ5C April 2021 – September 2022 ADS127L11
PRODUCTION DATA
The sinc4 + sinc1 filter is the cascade of two filter sections: sinc4 and sinc1. The OSR of the sinc4 stage is a constant value (32) and the programmable OSR of the sinc1 stage determines the output data rate. The sinc4 + sinc1 filter mode has comparably less latency time than that of the single-stage sinc4 filter. Table 8-6 summarizes the sinc4 + sinc1 filter characteristics.
SINC4 OSR | SINC1 OSR | DATA RATE (kSPS) | –3-dB FREQUENCY (kHz) | LATENCY TIME (µs)(1) |
---|---|---|---|---|
HIGH-SPEED MODE (fCLK = 25.6 MHz) | ||||
32 | 2 | 200 | 68.35 | 13.13 |
32 | 4 | 100 | 40.97 | 18.13 |
32 | 10 | 40 | 17.47 | 33.13 |
32 | 20 | 20 | 8.814 | 58.13 |
32 | 40 | 10 | 4.420 | 108.13 |
32 | 100 | 4 | 1.770 | 258.13 |
32 | 200 | 2 | 0.885 | 508.13 |
32 | 400 | 1 | 0.442 | 1008.13 |
32 | 1000 | 0.4 | 0.177 | 2508.13 |
LOW-SPEED MODE (fCLK = 3.2 MHz) | ||||
32 | 2 | 25 | 8.544 | 105.04 |
32 | 4 | 12.5 | 5.121 | 145.04 |
32 | 10 | 5 | 2.184 | 265.04 |
32 | 20 | 2.5 | 1.102 | 465.04 |
32 | 40 | 1.25 | 0.552 | 865.04 |
32 | 100 | 0.5 | 0.221 | 2065.04 |
32 | 200 | 0.25 | 0.111 | 4065.04 |
32 | 400 | 0.125 | 0.055 | 8065.04 |
32 | 1000 | 0.05 | 0.022 | 20065.04 |
Figure 8-16 shows the frequency response of the sinc4 + sinc1 filter for three values of OSR. The combined frequency response is the overlay of the sinc1 filter with the sinc4 filter. For low values of OSR, the response profile is dominated by the rolloff of the sinc4 filter. Nulls in the frequency response occur at n · fDATA, n = 1, 2, 3, and so on. At the null frequencies, the filter has zero gain.