ZHCSKD9 October 2019 ADS1235-Q1
PRODUCTION DATA.
The ADS1235-Q1 noise performance depends on the ADC configuration: data rate, PGA gain, digital filter configuration, and chop mode. The combination of the parameters affect noise performance. Two significant factors affecting noise performance are data rate and PGA gain. Since the profile of noise is predominantly white (flat vs frequency), decreasing the data rate proportionally decreases bandwidth and therefore, decreases total noise. Since the noise of the PGA is lower than that of the modulator, increasing the gain decreases overall conversion noise when treated as an input-referred quantity. Noise performance also depends on the digital filter and chop mode. As the order of the digital filter increases, the noise bandwidth correspondingly decreases resulting in decreased noise. Further, as a result of two-point data averaging performed in chop mode, noise decreases by √2 compared to normal operation.
Table 1 shows noise performance in units of μVRMS (RMS = root mean square) and in units of effective resolution (bits) under the conditions listed. The values in parenthesis are peak-to-peak values (µV) and noise free resolution (bits). Noise-free resolution is the resolution of the ADC with no code flicker. The noise-free resolution data are calculated based on the peak-to-peak noise data.
The effective resolution data listed in the tables are calculated using Equation 1:
where
The data shown in the noise performance table represent typical ADC performance at TA = 25°C. The noise-performance data are the standard deviation and peak-to-peak computations of the ADC data. The noise data are acquired with inputs shorted, based on consecutive ADC readings for a period of ten seconds or 8192 data points, whichever occurs first. Because of the statistical nature of noise, repeated noise measurements may yield higher or lower noise performance results.
DATA RATE | FILTER | NOISE, µVRMS (µVPP) | EFFECTIVE RESOLUTION (Bits), [NOISE-FREE RESOLUTION (Bits)] | ||||
---|---|---|---|---|---|---|---|
GAIN = 1 | GAIN = 64 | GAIN = 128 | GAIN = 1 | GAIN = 64 | GAIN = 128 | ||
2.5 SPS | FIR | 0.21 (0.6) | 0.008 (0.028) | 0.011 (0.042) | 24 (23.8) | 24 (22.4) | 22.7 (20.8) |
2.5 SPS | Sinc1 | 0.12 (0.3) | 0.009 (0.037) | 0.008 (0.033) | 24 (24) | 24 (22) | 23.2 (21.2) |
2.5 SPS | Sinc2 | 0.15 (0.3) | 0.007 (0.023) | 0.006 (0.021) | 24 (24) | 24 (22.7) | 23.7 (21.8) |
2.5 SPS | Sinc3 | 0.15 (0.3) | 0.007 (0.023) | 0.005 (0.014) | 24 (24) | 24 (22.7) | 24 (22.4) |
2.5 SPS | Sinc4 | 0.15 (0.3) | 0.005 (0.019) | 0.006 (0.019) | 24 (24) | 24 (23) | 23.7 (22) |
5 SPS | FIR | 0.29 (0.89) | 0.013 (0.051) | 0.013 (0.051) | 24 (23.2) | 23.6 (21.5) | 22.5 (20.5) |
5 SPS | Sinc1 | 0.15 (0.3) | 0.015 (0.051) | 0.01 (0.044) | 24 (24) | 23.4 (21.5) | 22.9 (20.8) |
5 SPS | Sinc2 | 0.17 (0.6) | 0.012 (0.047) | 0.009 (0.035) | 24 (23.8) | 23.7 (21.7) | 23 (21.1) |
5 SPS | Sinc3 | 0.12 (0.6) | 0.011 (0.047) | 0.008 (0.037) | 24 (23.8) | 23.7 (21.7) | 23.1 (21) |
5 SPS | Sinc4 | 0.088 (0.3) | 0.007 (0.028) | 0.007 (0.03) | 24 (24) | 24 (22.4) | 23.3 (21.3) |
10 SPS | FIR | 0.36 (1.5) | 0.022 (0.11) | 0.02 (0.096) | 24 (22.5) | 22.8 (20.5) | 21.9 (19.6) |
10 SPS | Sinc1 | 0.28 (0.89) | 0.015 (0.065) | 0.016 (0.082) | 24 (23.2) | 23.3 (21.2) | 22.2 (19.9) |
10 SPS | Sinc2 | 0.26 (0.89) | 0.015 (0.061) | 0.013 (0.065) | 24 (23.2) | 23.3 (21.3) | 22.5 (20.2) |
10 SPS | Sinc3 | 0.26 (0.6) | 0.014 (0.065) | 0.011 (0.047) | 24 (23.8) | 23.4 (21.2) | 22.7 (20.7) |
10 SPS | Sinc4 | 0.24 (0.6) | 0.013 (0.056) | 0.01 (0.042) | 24 (23.8) | 23.6 (21.4) | 22.9 (20.8) |
16.6 SPS | Sinc1 | 0.41 (1.8) | 0.025 (0.12) | 0.022 (0.12) | 24 (22.2) | 22.6 (20.3) | 21.8 (19.4) |
16.6 SPS | Sinc2 | 0.32 (1.5) | 0.018 (0.089) | 0.018 (0.096) | 24 (22.5) | 23 (20.8) | 22 (19.6) |
16.6 SPS | Sinc3 | 0.3 (1.2) | 0.017 (0.079) | 0.018 (0.091) | 24 (22.8) | 23.1 (20.9) | 22.1 (19.7) |
16.6 SPS | Sinc4 | 0.23 (1.2) | 0.015 (0.084) | 0.014 (0.072) | 24 (22.8) | 23.3 (20.8) | 22.4 (20) |
20 SPS | FIR | 0.51 (2.1) | 0.032 (0.16) | 0.029 (0.16) | 24 (22) | 22.2 (19.9) | 21.3 (18.9) |
20 SPS | Sinc1 | 0.44 (2.1) | 0.025 (0.13) | 0.026 (0.13) | 24 (22) | 22.6 (20.2) | 21.5 (19.2) |
20 SPS | Sinc2 | 0.36 (1.2) | 0.02 (0.12) | 0.02 (0.1) | 24 (22.8) | 22.9 (20.4) | 21.9 (19.5) |
20 SPS | Sinc3 | 0.32 (1.5) | 0.017 (0.089) | 0.018 (0.096) | 24 (22.5) | 23.1 (20.8) | 22 (19.6) |
20 SPS | Sinc4 | 0.3 (1.2) | 0.017 (0.084) | 0.018 (0.1) | 24 (22.8) | 23.1 (20.8) | 22.1 (19.6) |
50 SPS | Sinc1 | 0.63 (3.6) | 0.04 (0.25) | 0.038 (0.23) | 23.7 (21.2) | 21.9 (19.2) | 21 (18.4) |
50 SPS | Sinc2 | 0.57 (3) | 0.033 (0.21) | 0.032 (0.18) | 23.9 (21.5) | 22.2 (19.5) | 21.2 (18.7) |
50 SPS | Sinc3 | 0.53 (2.4) | 0.03 (0.19) | 0.03 (0.17) | 24 (21.8) | 22.3 (19.7) | 21.3 (18.8) |
50 SPS | Sinc4 | 0.49 (2.4) | 0.028 (0.15) | 0.026 (0.16) | 24 (21.8) | 22.4 (20) | 21.5 (18.9) |
60 SPS | Sinc1 | 0.71 (3.9) | 0.043 (0.27) | 0.042 (0.26) | 23.6 (21.1) | 21.8 (19.1) | 20.8 (18.2) |
60 SPS | Sinc2 | 0.6 (3.3) | 0.036 (0.24) | 0.034 (0.21) | 23.8 (21.4) | 22.1 (19.3) | 21.1 (18.5) |
60 SPS | Sinc3 | 0.56 (3) | 0.032 (0.19) | 0.03 (0.17) | 23.9 (21.5) | 22.2 (19.6) | 21.3 (18.8) |
60 SPS | Sinc4 | 0.53 (2.7) | 0.031 (0.19) | 0.03 (0.18) | 24 (21.6) | 22.3 (19.7) | 21.3 (18.7) |
100 SPS | Sinc1 | 0.8 (4.8) | 0.056 (0.34) | 0.054 (0.35) | 23.4 (20.8) | 21.4 (18.8) | 20.5 (17.8) |
100 SPS | Sinc2 | 0.68 (4.2) | 0.047 (0.29) | 0.043 (0.3) | 23.6 (21) | 21.7 (19) | 20.8 (18) |
100 SPS | Sinc3 | 0.67 (4.2) | 0.042 (0.28) | 0.041 (0.27) | 23.6 (21) | 21.8 (19.1) | 20.9 (18.1) |
100 SPS | Sinc4 | 0.62 (3.6) | 0.039 (0.24) | 0.039 (0.27) | 23.8 (21.2) | 21.9 (19.3) | 20.9 (18.2) |
400 SPS | Sinc1 | 1.4 (11) | 0.11 (0.81) | 0.11 (0.75) | 22.6 (19.6) | 20.4 (17.5) | 19.5 (16.7) |
400 SPS | Sinc2 | 1.2 (8.3) | 0.09 (0.64) | 0.086 (0.6) | 22.8 (20) | 20.7 (17.9) | 19.8 (17) |
400 SPS | Sinc3 | 1.1 (7.7) | 0.082 (0.61) | 0.078 (0.56) | 22.9 (20.1) | 20.9 (18) | 19.9 (17.1) |
400 SPS | Sinc4 | 1 (7.7) | 0.076 (0.59) | 0.072 (0.53) | 23 (20.1) | 21 (18) | 20 (17.2) |
1200 SPS | Sinc1 | 2.3 (17) | 0.18 (1.3) | 0.18 (1.4) | 21.9 (19) | 19.7 (16.9) | 18.8 (15.7) |
1200 SPS | Sinc2 | 2 (14) | 0.15 (1.2) | 0.15 (1.1) | 22.1 (19.3) | 20 (17) | 19 (16.1) |
1200 SPS | Sinc3 | 1.8 (13) | 0.14 (1) | 0.13 (1) | 22.2 (19.4) | 20.1 (17.2) | 19.2 (16.2) |
1200 SPS | Sinc4 | 1.7 (13) | 0.13 (1) | 0.13 (0.94) | 22.3 (19.4) | 20.2 (17.2) | 19.2 (16.3) |
2400 SPS | Sinc1 | 3.2 (26) | 0.25 (2) | 0.24 (1.8) | 21.4 (18.4) | 19.2 (16.2) | 18.3 (15.4) |
2400 SPS | Sinc2 | 2.7 (20) | 0.22 (1.7) | 0.21 (1.5) | 21.6 (18.7) | 19.5 (16.5) | 18.5 (15.6) |
2400 SPS | Sinc3 | 2.5 (18) | 0.2 (1.4) | 0.19 (1.4) | 21.7 (18.9) | 19.6 (16.7) | 18.6 (15.8) |
2400 SPS | Sinc4 | 2.3 (18) | 0.18 (1.5) | 0.18 (1.4) | 21.8 (18.9) | 19.7 (16.7) | 18.8 (15.8) |
4800 SPS | Sinc1 | 4.4 (35) | 0.34 (2.5) | 0.32 (2.4) | 20.9 (17.9) | 18.8 (15.9) | 17.9 (15) |
4800 SPS | Sinc2 | 3.9 (30) | 0.3 (2.3) | 0.29 (2.4) | 21.1 (18.1) | 19 (16.1) | 18 (15) |
4800 SPS | Sinc3 | 3.6 (27) | 0.28 (2) | 0.26 (2) | 21.2 (18.3) | 19.1 (16.3) | 18.2 (15.2) |
4800 SPS | Sinc4 | 3.4 (27) | 0.26 (1.9) | 0.25 (1.9) | 21.3 (18.3) | 19.2 (16.3) | 18.2 (15.3) |
7200 SPS | Sinc1 | 5.2 (42) | 0.38 (2.9) | 0.37 (3) | 20.7 (17.7) | 18.6 (15.7) | 17.7 (14.7) |
7200 SPS | Sinc2 | 4.7 (37) | 0.36 (2.8) | 0.34 (2.5) | 20.8 (17.9) | 18.7 (15.8) | 17.8 (14.9) |
7200 SPS | Sinc3 | 4.5 (35) | 0.34 (2.5) | 0.32 (2.4) | 20.9 (18) | 18.8 (15.9) | 17.9 (15) |
7200 SPS | Sinc4 | 4.2 (36) | 0.32 (2.5) | 0.31 (2.3) | 21 (17.9) | 18.9 (16) | 18 (15.1) |