ZHCSIZ6C October 2018 – June 2019 ADS125H02
PRODUCTION DATA.
Noise performance depends on the device configuration: data rate, input gain, digital filter mode, and auto-zero mode. Two significant factors affecting noise performance are data rate and input gain. Decreasing the data rate lowers the noise because the bandwidth is reduced over the fixed noise profile of the ADC. Increasing the gain reduces noise (when noise is treated as an input-referred quantity) because the noise of the PGA is lower than that of the ADC. Noise performance also depends on the digital filter and auto-zero mode. As the digital filter order increases, the bandwidth decreases, which results in lower noise. As a result of two-point data averaging in auto-zero mode, noise performance improves by √2 compared to the normal operating mode.
Table 1 lists the noise data of gain equal to 0.125 to 2 (corresponding input ranges of ±20 V to ±1.25 V) as input-referred values. Table 2 lists the noise data of gain equal to 4 to 128 (corresponding input ranges of ±625 mV to ±19.5 mV). The noise data are in units of µVRMS (RMS = root mean square) under the conditions listed. Values in parenthesis are peak-to-peak (µVpp).
The noise data represent typical ADC performance at TA = 25°C, 2.5-V reference voltage, and auto-zero mode disabled. The noise data are the standard deviation and peak-to-peak computations of the ADC data. The 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 measurements may yield higher or lower noise results. Similarly, longer periods of data acquisition may result in higher peak-to-peak noise results.
DATA RATE (SPS) | FILTER MODE | GAIN (Full-Scale Range) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0.125 (±20 V) | 0.1875 (±13.3 V) | 0.25 (±10 V) | 0.5 (±5 V) | 1 (±2.5 V) | 2 (±1.25 V) | ||||||||
2.5 | FIR | 1.3 | (4.8) | 0.89 | (3.6) | 0.69 | (2.1) | 0.49 | (1.9) | 0.37 | (1.5) | 0.17 | (0.67) |
2.5 | Sinc1 | 1.1 | (4.2) | 0.6 | (2.4) | 0.57 | (2.4) | 0.39 | (1.5) | 0.29 | (1) | 0.15 | (0.63) |
2.5 | Sinc2 | 1 | (3.6) | 0.68 | (2) | 0.44 | (1.8) | 0.32 | (1) | 0.26 | (0.97) | 0.12 | (0.52) |
2.5 | Sinc3 | 1.1 | (3) | 0.67 | (2) | 0.49 | (1.5) | 0.32 | (1) | 0.24 | (0.89) | 0.11 | (0.41) |
2.5 | Sinc4 | 0.98 | (3.6) | 0.64 | (2) | 0.48 | (1.2) | 0.3 | (1) | 0.26 | (0.97) | 0.11 | (0.41) |
5 | FIR | 1.7 | (6.6) | 1.2 | (4.8) | 0.93 | (4.2) | 0.57 | (2.5) | 0.45 | (2) | 0.24 | (1.2) |
5 | Sinc1 | 1.5 | (6.6) | 0.98 | (3.6) | 0.77 | (3.6) | 0.53 | (2.2) | 0.4 | (1.9) | 0.2 | (0.93) |
5 | Sinc2 | 1.3 | (4.8) | 0.91 | (4) | 0.68 | (2.4) | 0.44 | (1.8) | 0.35 | (1.6) | 0.18 | (0.82) |
5 | Sinc3 | 1.2 | (4.8) | 0.83 | (3.2) | 0.62 | (2.4) | 0.39 | (1.6) | 0.3 | (1.3) | 0.16 | (0.75) |
5 | Sinc4 | 1.2 | (3.6) | 0.75 | (3.2) | 0.54 | (2.1) | 0.38 | (1.5) | 0.27 | (1.2) | 0.14 | (0.56) |
10 | FIR | 2.4 | (11) | 1.6 | (7.9) | 1.2 | (5.7) | 0.82 | (4.3) | 0.69 | (3.3) | 0.34 | (1.7) |
10 | Sinc1 | 1.9 | (9.5) | 1.4 | (6.8) | 1.1 | (5.4) | 0.7 | (3.4) | 0.55 | (2.7) | 0.3 | (1.5) |
10 | Sinc2 | 1.7 | (8.9) | 1.2 | (5.6) | 0.9 | (4.5) | 0.56 | (2.7) | 0.47 | (2.3) | 0.24 | (1.2) |
10 | Sinc3 | 1.5 | (6.6) | 1.1 | (5.2) | 0.89 | (4.2) | 0.54 | (2.7) | 0.46 | (2.5) | 0.24 | (1.1) |
10 | Sinc4 | 1.5 | (6.6) | 0.99 | (4.4) | 0.79 | (3.6) | 0.49 | (2.4) | 0.39 | (1.9) | 0.2 | (1) |
16.6 | Sinc1 | 2.6 | (11) | 1.7 | (8.7) | 1.4 | (6.6) | 0.87 | (4.5) | 0.72 | (3.5) | 0.37 | (2) |
16.6 | Sinc2 | 2.1 | (10) | 1.5 | (7.5) | 1.1 | (5.7) | 0.78 | (3.7) | 0.62 | (3.2) | 0.32 | (1.6) |
16.6 | Sinc3 | 1.9 | (9.5) | 1.4 | (7.2) | 1.1 | (5.1) | 0.72 | (3.6) | 0.54 | (2.5) | 0.27 | (1.3) |
16.6 | Sinc4 | 1.8 | (7.7) | 1.3 | (6.4) | 0.97 | (4.8) | 0.65 | (3.1) | 0.48 | (2.5) | 0.24 | (1.2) |
20 | FIR | 3 | (15) | 2.1 | (11) | 1.8 | (8.6) | 1.1 | (5.2) | 0.89 | (4.8) | 0.46 | (2.6) |
20 | Sinc1 | 2.7 | (13) | 1.9 | (9.5) | 1.5 | (7.5) | 0.97 | (5.5) | 0.76 | (4.2) | 0.43 | (2.3) |
20 | Sinc2 | 2.2 | (11) | 1.5 | (7.2) | 1.3 | (6) | 0.83 | (4.2) | 0.69 | (3.7) | 0.35 | (1.8) |
20 | Sinc3 | 2.1 | (10) | 1.6 | (8.3) | 1.2 | (5.4) | 0.77 | (4) | 0.64 | (3.1) | 0.31 | (1.6) |
20 | Sinc4 | 2 | (9.5) | 1.3 | (6.8) | 1.1 | (4.8) | 0.65 | (3.1) | 0.56 | (2.7) | 0.28 | (1.4) |
50 | Sinc1 | 4.1 | (24) | 2.9 | (17) | 2.3 | (14) | 1.5 | (7.7) | 1.2 | (7.5) | 0.64 | (3.7) |
50 | Sinc2 | 3.2 | (18) | 2.3 | (12) | 1.9 | (11) | 1.3 | (7) | 1.1 | (5.8) | 0.54 | (3.1) |
50 | Sinc3 | 3.3 | (18) | 2.2 | (13) | 1.8 | (9.2) | 1.2 | (6.7) | 0.93 | (5.3) | 0.49 | (3) |
50 | Sinc4 | 3.1 | (17) | 2 | (11) | 1.6 | (8.3) | 1 | (5.8) | 0.87 | (4.7) | 0.43 | (2.4) |
60 | Sinc1 | 4.5 | (27) | 3.1 | (17) | 2.4 | (13) | 1.6 | (9.2) | 1.4 | (8.3) | 0.69 | (3.8) |
60 | Sinc2 | 3.8 | (23) | 2.6 | (14) | 2.1 | (11) | 1.4 | (7.3) | 1.2 | (5.9) | 0.57 | (3.1) |
60 | Sinc3 | 3.4 | (19) | 2.3 | (13) | 1.8 | (9.2) | 1.3 | (6.9) | 1 | (5.4) | 0.54 | (3.1) |
60 | Sinc4 | 3.3 | (18) | 2.1 | (12) | 1.9 | (9.8) | 1.2 | (6.6) | 0.95 | (5.2) | 0.52 | (2.8) |
100 | Sinc1 | 5.6 | (34) | 4.1 | (23) | 3.3 | (20) | 2.1 | (12) | 1.8 | (9.7) | 0.91 | (5.7) |
100 | Sinc2 | 4.9 | (30) | 3.4 | (21) | 2.7 | (16) | 1.8 | (11) | 1.5 | (8.7) | 0.75 | (4.4) |
100 | Sinc3 | 4.4 | (26) | 3.1 | (18) | 2.5 | (14) | 1.7 | (10) | 1.3 | (8.2) | 0.69 | (4.2) |
100 | Sinc4 | 4.1 | (24) | 2.9 | (17) | 2.3 | (14) | 1.5 | (8.5) | 1.3 | (7.7) | 0.63 | (4) |
400 | Sinc1 | 12 | (74) | 8.1 | (55) | 6.4 | (43) | 4.3 | (27) | 3.6 | (25) | 1.8 | (11) |
400 | Sinc2 | 9.3 | (60) | 6.7 | (44) | 5.3 | (32) | 3.5 | (23) | 2.9 | (19) | 1.5 | (10) |
400 | Sinc3 | 8.6 | (54) | 6.2 | (39) | 4.9 | (32) | 3.2 | (20) | 2.7 | (17) | 1.4 | (9.1) |
400 | Sinc4 | 8 | (52) | 5.6 | (37) | 4.5 | (30) | 3 | (20) | 2.5 | (16) | 1.3 | (8.3) |
1200 | Sinc1 | 20 | (140) | 14 | (98) | 11 | (75) | 7.3 | (48) | 6 | (40) | 3.1 | (20) |
1200 | Sinc2 | 17 | (110) | 12 | (78) | 9.2 | (62) | 6.1 | (41) | 5 | (33) | 2.6 | (18) |
1200 | Sinc3 | 15 | (100) | 11 | (72) | 8.4 | (56) | 5.6 | (37) | 4.6 | (31) | 2.4 | (16) |
1200 | Sinc4 | 14 | (95) | 9.9 | (68) | 7.8 | (51) | 5.2 | (37) | 4.3 | (29) | 2.2 | (15) |
2400 | Sinc1 | 27 | (200) | 19 | (140) | 15 | (110) | 10 | (72) | 8.3 | (60) | 4.2 | (30) |
2400 | Sinc2 | 23 | (180) | 16 | (120) | 13 | (97) | 8.7 | (62) | 7 | (53) | 3.6 | (26) |
2400 | Sinc3 | 21 | (160) | 15 | (110) | 12 | (94) | 7.9 | (59) | 6.5 | (50) | 3.3 | (23) |
2400 | Sinc4 | 20 | (140) | 14 | (100) | 11 | (78) | 7.3 | (53) | 6 | (43) | 3.1 | (22) |
4800 | Sinc1 | 37 | (270) | 26 | (200) | 21 | (160) | 14 | (110) | 11 | (83) | 5.6 | (42) |
4800 | Sinc2 | 33 | (250) | 23 | (170) | 18 | (140) | 12 | (88) | 9.8 | (73) | 5 | (40) |
4800 | Sinc3 | 31 | (230) | 21 | (150) | 17 | (130) | 11 | (83) | 9 | (65) | 4.7 | (36) |
4800 | Sinc4 | 29 | (220) | 20 | (150) | 16 | (120) | 11 | (81) | 8.5 | (63) | 4.4 | (33) |
7200 | Sinc1 | 44 | (330) | 31 | (230) | 24 | (180) | 16 | (120) | 13 | (98) | 6.5 | (48) |
7200 | Sinc2 | 39 | (300) | 28 | (210) | 22 | (170) | 14 | (100) | 12 | (90) | 5.9 | (46) |
7200 | Sinc3 | 37 | (280) | 26 | (200) | 21 | (160) | 13 | (100) | 11 | (82) | 5.5 | (41) |
7200 | Sinc4 | 35 | (260) | 25 | (180) | 20 | (150) | 13 | (95) | 10 | (81) | 5.3 | (41) |
14400 | Sinc5 | 53 | (430) | 36 | (290) | 29 | (220) | 18 | (140) | 14 | (120) | 7.4 | (58) |
19200 | Sinc5 | 72 | (560) | 50 | (390) | 39 | (320) | 23 | (180) | 17 | (130) | 8.8 | (71) |
25600 | Sinc5 | 150 | (1300) | 100 | (870) | 79 | (640) | 42 | (350) | 26 | (220) | 13 | (110) |
40000 | Sinc5 | 250 | (2000) | 160 | (1300) | 120 | (1000) | 65 | (530) | 37 | (310) | 19 | (150) |
DATA RATE (SPS) | FILTER MODE | GAIN (Full-Scale Range) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
4 (±625 mV) | 8 (±312 mV) | 16 (±156 mV) | 32 (±78.1 mV) | 64 (±39.1 mV) | 128 (±19.5 mV) | ||||||||
2.5 | FIR | 0.082 | (0.35) | 0.051 | (0.2) | 0.032 | (0.14) | 0.027 | (0.11) | 0.027 | (0.1) | 0.029 | (0.12) |
2.5 | Sinc1 | 0.088 | (0.35) | 0.05 | (0.19) | 0.024 | (0.089) | 0.024 | (0.089) | 0.023 | (0.098) | 0.024 | (0.1) |
2.5 | Sinc2 | 0.059 | (0.24) | 0.037 | (0.14) | 0.021 | (0.084) | 0.018 | (0.072) | 0.017 | (0.076) | 0.019 | (0.076) |
2.5 | Sinc3 | 0.06 | (0.24) | 0.034 | (0.13) | 0.019 | (0.075) | 0.017 | (0.07) | 0.016 | (0.073) | 0.018 | (0.075) |
2.5 | Sinc4 | 0.054 | (0.19) | 0.034 | (0.13) | 0.019 | (0.075) | 0.016 | (0.065) | 0.015 | (0.062) | 0.016 | (0.069) |
5 | FIR | 0.12 | (0.52) | 0.071 | (0.33) | 0.046 | (0.21) | 0.038 | (0.19) | 0.039 | (0.17) | 0.037 | (0.18) |
5 | Sinc1 | 0.11 | (0.48) | 0.061 | (0.28) | 0.038 | (0.18) | 0.029 | (0.14) | 0.029 | (0.15) | 0.029 | (0.13) |
5 | Sinc2 | 0.093 | (0.43) | 0.048 | (0.21) | 0.029 | (0.14) | 0.024 | (0.11) | 0.026 | (0.12) | 0.023 | (0.1) |
5 | Sinc3 | 0.081 | (0.41) | 0.044 | (0.2) | 0.03 | (0.13) | 0.023 | (0.1) | 0.022 | (0.1) | 0.022 | (0.11) |
5 | Sinc4 | 0.066 | (0.3) | 0.043 | (0.2) | 0.027 | (0.13) | 0.022 | (0.093) | 0.022 | (0.11) | 0.021 | (0.096) |
10 | FIR | 0.19 | (1) | 0.099 | (0.51) | 0.064 | (0.36) | 0.053 | (0.29) | 0.051 | (0.3) | 0.054 | (0.3) |
10 | Sinc1 | 0.16 | (0.82) | 0.086 | (0.46) | 0.054 | (0.3) | 0.045 | (0.22) | 0.043 | (0.21) | 0.044 | (0.23) |
10 | Sinc2 | 0.12 | (0.56) | 0.068 | (0.36) | 0.044 | (0.23) | 0.037 | (0.2) | 0.034 | (0.18) | 0.033 | (0.18) |
10 | Sinc3 | 0.11 | (0.52) | 0.066 | (0.31) | 0.042 | (0.21) | 0.032 | (0.17) | 0.032 | (0.16) | 0.032 | (0.16) |
10 | Sinc4 | 0.096 | (0.45) | 0.059 | (0.31) | 0.039 | (0.2) | 0.032 | (0.17) | 0.031 | (0.16) | 0.03 | (0.15) |
16.6 | Sinc1 | 0.19 | (1) | 0.11 | (0.56) | 0.075 | (0.38) | 0.054 | (0.3) | 0.055 | (0.29) | 0.056 | (0.31) |
16.6 | Sinc2 | 0.16 | (0.89) | 0.086 | (0.4) | 0.054 | (0.27) | 0.044 | (0.22) | 0.049 | (0.24) | 0.046 | (0.24) |
16.6 | Sinc3 | 0.15 | (0.73) | 0.084 | (0.41) | 0.053 | (0.27) | 0.041 | (0.22) | 0.04 | (0.22) | 0.041 | (0.2) |
16.6 | Sinc4 | 0.13 | (0.67) | 0.076 | (0.39) | 0.053 | (0.29) | 0.042 | (0.24) | 0.04 | (0.21) | 0.036 | (0.17) |
20 | FIR | 0.24 | (1.2) | 0.14 | (0.72) | 0.088 | (0.45) | 0.072 | (0.38) | 0.071 | (0.37) | 0.074 | (0.37) |
20 | Sinc1 | 0.22 | (1.1) | 0.12 | (0.58) | 0.079 | (0.41) | 0.064 | (0.32) | 0.061 | (0.32) | 0.06 | (0.34) |
20 | Sinc2 | 0.18 | (1) | 0.1 | (0.57) | 0.062 | (0.34) | 0.049 | (0.25) | 0.049 | (0.26) | 0.047 | (0.29) |
20 | Sinc3 | 0.16 | (0.89) | 0.089 | (0.48) | 0.063 | (0.32) | 0.046 | (0.22) | 0.045 | (0.21) | 0.045 | (0.23) |
20 | Sinc4 | 0.15 | (0.82) | 0.083 | (0.41) | 0.056 | (0.29) | 0.045 | (0.23) | 0.042 | (0.22) | 0.046 | (0.24) |
50 | Sinc1 | 0.35 | (2.1) | 0.19 | (1.1) | 0.12 | (0.69) | 0.097 | (0.52) | 0.096 | (0.57) | 0.098 | (0.58) |
50 | Sinc2 | 0.28 | (1.6) | 0.15 | (0.84) | 0.099 | (0.56) | 0.075 | (0.43) | 0.077 | (0.43) | 0.076 | (0.46) |
50 | Sinc3 | 0.25 | (1.5) | 0.14 | (0.75) | 0.093 | (0.51) | 0.074 | (0.41) | 0.07 | (0.38) | 0.071 | (0.37) |
50 | Sinc4 | 0.23 | (1.4) | 0.13 | (0.76) | 0.087 | (0.47) | 0.066 | (0.37) | 0.065 | (0.35) | 0.065 | (0.37) |
60 | Sinc1 | 0.38 | (2.2) | 0.21 | (1.2) | 0.14 | (0.79) | 0.11 | (0.57) | 0.1 | (0.59) | 0.1 | (0.6) |
60 | Sinc2 | 0.3 | (1.7) | 0.17 | (0.93) | 0.11 | (0.66) | 0.085 | (0.47) | 0.084 | (0.49) | 0.083 | (0.49) |
60 | Sinc3 | 0.27 | (1.6) | 0.15 | (0.79) | 0.097 | (0.53) | 0.078 | (0.43) | 0.078 | (0.43) | 0.076 | (0.42) |
60 | Sinc4 | 0.27 | (1.6) | 0.14 | (0.89) | 0.092 | (0.5) | 0.075 | (0.46) | 0.076 | (0.4) | 0.073 | (0.4) |
100 | Sinc1 | 0.49 | (2.8) | 0.27 | (1.5) | 0.17 | (1) | 0.14 | (0.81) | 0.14 | (0.88) | 0.13 | (0.81) |
100 | Sinc2 | 0.39 | (2.3) | 0.22 | (1.4) | 0.14 | (0.87) | 0.11 | (0.63) | 0.11 | (0.69) | 0.11 | (0.66) |
100 | Sinc3 | 0.35 | (2.1) | 0.2 | (1.2) | 0.13 | (0.75) | 0.1 | (0.63) | 0.1 | (0.61) | 0.1 | (0.69) |
100 | Sinc4 | 0.32 | (2) | 0.18 | (1.2) | 0.13 | (0.73) | 0.094 | (0.57) | 0.092 | (0.56) | 0.093 | (0.57) |
400 | Sinc1 | 0.94 | (6) | 0.53 | (3.5) | 0.34 | (2.1) | 0.27 | (1.8) | 0.27 | (1.7) | 0.27 | (1.8) |
400 | Sinc2 | 0.78 | (5.2) | 0.44 | (3.1) | 0.29 | (1.8) | 0.22 | (1.4) | 0.22 | (1.4) | 0.22 | (1.4) |
400 | Sinc3 | 0.72 | (4.6) | 0.4 | (2.6) | 0.26 | (1.6) | 0.2 | (1.3) | 0.2 | (1.3) | 0.2 | (1.3) |
400 | Sinc4 | 0.67 | (4.2) | 0.37 | (2.4) | 0.24 | (1.6) | 0.19 | (1.2) | 0.19 | (1.2) | 0.19 | (1.1) |
1200 | Sinc1 | 1.6 | (12) | 0.91 | (6.3) | 0.59 | (4.1) | 0.46 | (3.1) | 0.45 | (3.1) | 0.45 | (3.1) |
1200 | Sinc2 | 1.3 | (9.3) | 0.76 | (5.2) | 0.49 | (3.2) | 0.39 | (2.6) | 0.38 | (2.6) | 0.38 | (2.6) |
1200 | Sinc3 | 1.2 | (8.2) | 0.69 | (4.7) | 0.45 | (3.1) | 0.35 | (2.4) | 0.35 | (2.4) | 0.35 | (2.2) |
1200 | Sinc4 | 1.2 | (7.6) | 0.64 | (4.3) | 0.41 | (2.7) | 0.33 | (2.3) | 0.32 | (2.2) | 0.32 | (2.3) |
2400 | Sinc1 | 2.2 | (17) | 1.2 | (8.9) | 0.81 | (5.8) | 0.64 | (4.5) | 0.62 | (4.5) | 0.62 | (4.6) |
2400 | Sinc2 | 1.9 | (14) | 1.1 | (7.7) | 0.68 | (5) | 0.54 | (3.9) | 0.54 | (3.9) | 0.54 | (4) |
2400 | Sinc3 | 1.7 | (14) | 0.97 | (7.1) | 0.62 | (4.4) | 0.49 | (3.5) | 0.48 | (3.4) | 0.49 | (3.5) |
2400 | Sinc4 | 1.6 | (12) | 0.91 | (6.7) | 0.59 | (4.1) | 0.46 | (3.5) | 0.46 | (3.4) | 0.46 | (3.4) |
4800 | Sinc1 | 3 | (23) | 1.6 | (13) | 1.1 | (7.8) | 0.83 | (6.2) | 0.83 | (6.2) | 0.82 | (6.1) |
4800 | Sinc2 | 2.6 | (20) | 1.5 | (12) | 0.95 | (7.2) | 0.75 | (5.6) | 0.74 | (5.4) | 0.73 | (5.5) |
4800 | Sinc3 | 2.4 | (19) | 1.4 | (10) | 0.89 | (6.4) | 0.69 | (5) | 0.68 | (5.2) | 0.69 | (5.5) |
4800 | Sinc4 | 2.3 | (17) | 1.3 | (9.8) | 0.82 | (6.2) | 0.64 | (5) | 0.65 | (4.9) | 0.64 | (4.9) |
7200 | Sinc1 | 3.3 | (25) | 1.9 | (15) | 1.2 | (9) | 0.95 | (7) | 0.94 | (6.9) | 0.94 | (7.1) |
7200 | Sinc2 | 3.1 | (24) | 1.7 | (13) | 1.1 | (8.7) | 0.87 | (6.6) | 0.86 | (6.5) | 0.86 | (6.4) |
7200 | Sinc3 | 2.9 | (22) | 1.6 | (12) | 1.1 | (7.9) | 0.83 | (6.1) | 0.82 | (6.2) | 0.82 | (6.4) |
7200 | Sinc4 | 2.8 | (21) | 1.6 | (12) | 1 | (7.7) | 0.79 | (5.8) | 0.78 | (6) | 0.78 | (5.8) |
14400 | Sinc5 | 3.8 | (29) | 2.1 | (17) | 1.4 | (11) | 1.1 | (8.4) | 1.1 | (8.1) | 1 | (8.4) |
19200 | Sinc5 | 4.6 | (36) | 2.5 | (20) | 1.6 | (13) | 1.2 | (9.6) | 1.2 | (9.3) | 1.2 | (9.5) |
25600 | Sinc5 | 6.7 | (56) | 3.6 | (29) | 2.1 | (17) | 1.5 | (13) | 1.4 | (12) | 1.4 | (12) |
40000 | Sinc5 | 9.6 | (80) | 5 | (43) | 2.9 | (23) | 2 | (16) | 1.8 | (15) | 1.8 | (15) |
ADC noise performance can also be expressed as effective resolution and noise-free resolution (bits). The resolution in bits are computed from the measured noise data. Effective resolution is computed from the RMS value of the measured noise data. Noise-free resolution is computed from the peak-to-peak value of the measured noise data, and is therefore the resolution with no code flicker. Equation 1 is used to compute effective resolution (bits) and noise-free resolution (bits) based on the noise values listed in Table 1 and Table 2.
where
For example, with a full-scale range = ±13.3 V, data rate = 20 SPS, and filter mode = FIR, the RMS noise value (from Table 1) is 2.1 µV. The effective resolution is: 3.32 log (26.6 V / 2.1 µV) = 23.6 bits.
Figure 52 and Figure 53 show effective resolution (bits) using Equation 1. Figure 54 and Figure 55 show the noise-free resolution (bits) using Equation 1. The data are based on 2.5-V reference operation and the sinc3 filter mode. Effective resolution and noise-free resolution (bits) are improved by increasing the reference voltage (up to 5 V).