MAX1402_07 Datasheet, PDF (28/38 Pages) Maxim Integrated Products – +5V, 18-Bit, Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC

+5V, 18-Bit, Low-Power, Multichannel,
Oversampling (Sigma-Delta) ADC
Table 16b. MAX1402 Noise vs. Gain and Output Data Rate—Buffered Mode,
V_REF = 2.5V, f_CLKIN = 2.4576MHz
OUTPUT
DATA
RATE
(sps)
-3dB
FREQ.
(Hz)
x1
TYPICAL OUTPUT NOISE IN µV_RMS
PROGRAMMABLE GAIN
x2
x4
x8
x16
x32
x64
x128
50
13.1
6.05
4.13
2.35
1.50
1.40
1.32
1.37
1.39
60
15.7
7.11
4.24
2.54
1.64
1.49
1.53
1.49
1.48
300
78.6
142.02 71.62
35.65
18.32
9.35
5.60
4.10
3.52
600
157.2 823.33 405.95 195.95 102.14 50.28
25.85
13.75
7.78
100
26.2
8.10
3.66
2.25
1.52
1.34
1.31
1.34
1.35
120
31.4
8.37
4.12
2.53
1.64
1.45
1.49
1.45
1.46
600
157.2 143.45 69.52
36.04
17.77
9.32
5.48
3.92
3.41
1200
314.4 830.30 408.48 201.87 101.39 52.39
26.77
13.50
7.87
200
52.4
6.55
3.21
1.92
1.35
1.24
1.16
1.16
1.10
240
62.9
7.40
3.89
2.24
1.47
1.35
1.29
1.22
1.25
1200
314.4 148.57 73.71
36.80
18.08
9.92
5.26
3.64
3.02
2400
628.8 851.32 408.09 202.57 105.18 52.98
25.71
13.33
7.97
400
104.8
6.60
3.83
2.21
1.38
1.28
1.21
1.17
1.21
480
125.7
7.58
4.14
2.28
1.58
1.40
1.34
1.30
1.31
2400
628.8 144.96 68.92
35.92
17.36
9.52
5.45
3.79
3.21
4800
1258 803.87 394.00 205.60 102.18 52.48
26.07
13.59
7.89
BIT
STATUS
MF1:MF0 = 0
FS1:FS0 = 0
FS1:FS0 = 1
FS1:FS0 = 2
FS1:FS0 = 3
MF1:MF0 = 1
FS1:FS0 = 0
FS1:FS0 = 1
FS1:FS0 = 2
FS1:FS0 = 3
MF1:MF0 = 2
FS1:FS0 = 0
FS1:FS0 = 1
FS1:FS0 = 2
FS1:FS0 = 3
MF1:MF0 = 3
FS1:FS0 = 0
FS1:FS0 = 1
FS1:FS0 = 2
FS1:FS0 = 3
20
19
18
17
16
15
14
13
12
11
10
1
a) BUFF = 0
CLK = 1
FS1: FS0 = 0 OR 1
FS1: FS0 = 2
FS1: FS0 = 3
CLK = 1
BUFF = 0
2 4 8 16 32 64 128
GAIN (V/V)
Figure 8. Effective Resolution vs. Gain and Notch Frequency
Effective Resolution = (SNR_dB - 1.76dB) / 6.02
The maximum possible signal divided by the noise of
the device, SNR_dB, is defined as the ratio of the input
full-scale voltage (i.e., 2 · V_REFIN / GAIN) to the output
rms noise. Note that it is not calculated using peak-to-
20
19
18
17
16
15
14
13
12
11
10
1
b) BUFF = 1
FS1: FS0 = 0 OR 1
FS1: FS0 = 2
FS1: FS0 = 3
CLK = 1
BUFF = 1
2 4 8 16 32 64 128
GAIN (V/V)
peak output noise numbers. Peak-to-peak noise num-
bers can be up to 6.6 times the rms numbers, while
effective resolution numbers based on peak-to-peak
noise can be 2.5 bits below the effective resolution
based on rms noise, as quoted in the tables.
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