JAJSEC1C November 2019 – July 2020 ADS8686S
PRODUCTION DATA
The ADS8686S features an optional digital second-order sinc filter that can be used in slower throughput applications requiring lower noise and higher dynamic range. As explained in Table 7-3, the oversampling ratio of the digital filter is determined by the configuration of the OS[2:0] pins in hardware mode or through the OS bits programming in software mode. When enabled, the oversampling is applicable for all channels. The overall throughput of the ADC decreases proportionally with the increase to the oversampling ratio. When the oversampling ratio increases, there is a proportional improvement in the SNR performance and decrease in the bandwidth of the input signal.
In oversampling mode, the ADC takes the first sample for each channel at the rising edge of the CONVST signal. After converting the first sample, the subsequent samples are taken by an internally generated sampling control signal. The samples are then averaged to reduce the noise of the signal chain as well as to improve the SNR of the ADC. The final output is also decimated to provide a 16-bit output for each channel.
If oversampling is enabled with the sequencer in burst mode, the extra samples are gathered for a given channel before the sequencer moves on to the next channel.
OSx PINS, OS BITS |
OSR | LPF OPTION | TYPICAL SNR (dB) | −3-dB BANDWIDTH (kHz) | |||||
---|---|---|---|---|---|---|---|---|---|
±2.5-V RANGE | ±3-V RANGE | ±5-V RANGE | ±6-V RANGE | ±10-V RANGE | ±12-V RANGE | ±10-V RANGE | |||
000 | No OSR | LPF 1 | 86.99 | 87.32 | 89.55 | 89.69 | 90.69 | 90.53 | 39.4 |
001 | 2 | LPF 1 | 87.6 | 87.89 | 90.25 | 90.4 | 91.53 | 91.35 | 39.4 |
010 | 4 | LPF 1 | 88.04 | 88.36 | 90.89 | 91.01 | 92.37 | 92.17 | 37.5 |
011 | 8 | LPF 1 | 88.74 | 89.07 | 91.65 | 97.79 | 93.29 | 93.08 | 32.0 |
100 | 16 | LPF 1 | 89.97 | 90.28 | 92.76 | 92.92 | 94.4 | 94.21 | 22.4 |
101 | 32 | LPF 1 | 91.98 | 92.21 | 94.33 | 94.45 | 95.65 | 95.53 | 12.9 |
110 | 64 | LPF 1 | 93.61 | 93.95 | 95.68 | 95.83 | 96.8 | 96.69 | 6.8 |
111 | 128 | LPF 1 | 95.53 | 95.9 | 97.27 | 97.42 | 97.97 | 98.01 | 3.4 |
000 | No OSR | LPF 2 | 89.05 | 89.35 | 90.98 | 91.11 | 91.92 | 91.85 | 15.4 |
001 | 2 | LPF 2 | 89.94 | 90.18 | 91.91 | 92.01 | 92.94 | 92.84 | 15.4 |
010 | 4 | LPF 2 | 90.4 | 90.65 | 92.62 | 92.73 | 93.82 | 93.72 | 15.3 |
011 | 8 | LPF 2 | 90.81 | 91.08 | 93.2 | 93.31 | 94.53 | 94.42 | 14.8 |
100 | 16 | LPF 2 | 91.39 | 91.7 | 93.82 | 93.95 | 95.19 | 95.07 | 13.3 |
101 | 32 | LPF 2 | 92.74 | 92.96 | 94.84 | 94.95 | 95.99 | 95.87 | 10.1 |
110 | 64 | LPF 2 | 93.85 | 94.2 | 95.91 | 96.04 | 96.88 | 96.85 | 6.2 |
111 | 128 | LPF 2 | 95.62 | 95.94 | 97.28 | 97.47 | 98.04 | 98.02 | 3.4 |
000 | No OSR | LPF 3 | 77.29 | 77.33 | 81.12 | 81.25 | 84.33 | 83.58 | 399.9 |
001 | 2 | LPF 3 | 80.11 | 80.34 | 83.79 | 83.95 | 86.77 | 86.26 | 210.3 |
010 | 4 | LPF 3 | 82.97 | 83.24 | 86.52 | 86.67 | 89.25 | 88.87 | 108.8 |
011 | 8 | LPF 3 | 85.82 | 86.1 | 89.14 | 89.31 | 91.58 | 91.28 | 55.0 |
100 | 16 | LPF 3 | 88.53 | 88.81 | 91.56 | 91.73 | 93.59 | 93.38 | 27.6 |
101 | 32 | LPF 3 | 91.26 | 91.5 | 93.78 | 93.89 | 95.28 | 95.12 | 13.8 |
110 | 64 | LPF 3 | 93.29 | 93.64 | 95.49 | 95.6 | 96.62 | 96.52 | 6.9 |
111 | 128 | LPF 3 | 95.46 | 95.79 | 97.1 | 97.27 | 97.94 | 97.89 | 3.5 |