Summary Of Filter Options - Analog Devices AD7195 Manual

The 50 Hz/60 Hz rejection can be improved by setting the
REJ60 bit in the mode register to 1. With FS[9:0] set to 96 and
REJ60 set to 1, the filter response shown in Figure 49 is achieved.
The output data rate is unchanged, but the 50 Hz/60 Hz ± 1 Hz
rejection improves to 73 dB typically.
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
0 25
(FS[9:0] = 96, Chop Enabled, REJ60 = 1)
Table 35. Filter Summary
Filter
Sinc 4 , Chop Disabled
4
Sinc , Chop Disabled
3
Sinc , Chop Disabled
4
Sinc , Chop Disabled
3
Sinc , Chop Disabled
4
Sinc , Chop Disabled
4
Sinc , Chop Disabled
3
Sinc , Chop Disabled
3
Sinc , Chop Disabled
Sinc 4
, Chop Disabled
Sinc 3 , Chop Disabled
Sinc 4 , Chop Disabled, Zero
Latency
4
Sinc , Chop Disabled, Zero
Latency
4
Sinc , Chop Disabled, Zero
Latency
Sinc 4 , Chop Enabled
Sinc 3 , Chop Enabled
1 These calculations assume a 4.92 MHz stable master clock.
2
Throughput is the rate at which conversions are available when several channels are enabled. In zero latency mode, the output data rate and throughput are equal.
3
For output dates rates greater than 1 kHz, the sinc
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50 75 100 125
FREQUENCY (Hz)
3
Figure 49. Sinc Filter Response
1
Output Data
FS[9:0] Rate (Hz)
3 1 4800
5 960
5 960
480 10
480 10
96 50
96 50
96 50
96 50
80 60
80 60
96 12.5
96 12.5
80 15
96 12.5
96 16.7
4
filter is recommended.

SUMMARY OF FILTER OPTIONS

The AD7195 has several filter options. The filter that is chosen
affects the output data rate, settling time, the rms noise, the stop
band attenuation, and the 50 Hz/60 Hz rejection.
Table 35 shows some sample configurations and the corres-
ponding performance in terms of throughput, settling time and
50 Hz/60 Hz rejection.
150
Settling
Time (ms) Throughput
0.83 1200
4.17 240
3.125 320
400 2.5
300 3.33
80 12.5
80 12.5
60 16.7
60 16.7
66.67 15
50 20
80 12.5
80 12.5
66.67 15
160 6.25
120 8.33
Rev. 0 | Page 41 of 44
2
(Hz) REJ60 50 Hz Rejection (dB)
0 No 50 Hz or 60 Hz rejection
0 No 50 Hz or 60 Hz rejection
0 No 50 Hz or 60 Hz rejection
0 120 dB ( 50 Hz and 60 Hz)
0 100 dB (50 Hz and 60 Hz)
0 120 dB (50 Hz only)
1 82 dB ( 50 Hz and 60 Hz)
0 95 dB (50 Hz only)
1 67 dB ( 50 Hz and 60 Hz)
0 120 dB (60 Hz only)
0 95 dB (60 Hz only)
0 120 dB (50 Hz only)
1 82 dB ( 50 Hz and 60 Hz)
0 120 dB (60 Hz only)
1 80 dB (50 Hz and 60 Hz)
1 67 dB (50 Hz and 60 Hz)
AD7195