ZHCSMK4A september 2022 – july 2023 ADS131B26-Q1
PRODUCTION DATA
The ADC2y ΔΣ modulator bitstream feeds into a digital filter. The digital filter is a linear phase, finite impulse response (FIR), low-pass sinc filter that attenuates the out-of-band quantization noise of the ΔΣ modulator.
In contrast to ADC1y, ADC2y always operates in a single-shot conversion mode fashion. The ADC2y sequencer triggers the individual conversions. The digital filter resets at the start of every conversion and must completely settle for every conversion. ADC2y only outputs settled conversion results, assuming that the input signal settled before the conversion started.
Use the OSR2y[1:0] bits to select the conversion time for ADC2y. For an OSR = 64, the filter is comprised of a pure sinc3 filter. A sinc3 filter takes three cycles to settle. Therefore, the conversion time for an OSR = 64 equals (3 × 64 / fMOD = 192 tMOD = 384 tMCLK). For higher OSR settings the sinc3 filter is followed by a sinc1 filter.
Table 9-9 lists an overview of the OSR settings and the corresponding conversion times for ADC2y based on a nominal MCLK frequency of 8.192 MHz.
OSR | CONVERSION TIME | |||
---|---|---|---|---|
OVERALL | SINC3 | SINC1 | tMCLK | μs |
64 | 64 | 1 | 384 tMCLK | 46.87 μs |
128 | 64 | 2 | 512 tMCLK | 62.50 μs |
256 | 64 | 4 | 768 tMCLK | 93.75 μs |
512 | 64 | 8 | 1280 tMCLK | 156.25 μs |