AD7714
BUFFERED MODE NOISE
Table III shows the typical output rms noise and effective resolution for some typical notch and –3 dB frequencies for the AD7714-
5 with fCLK IN = 2.4576 MHz and BUFFER = +5 V. Table IV gives the information for the AD7714-3 again with fCLK IN = 2.4576
MHz and BUFFER = +5 V. The numbers given are for the bipolar input ranges and are generated with a differential analog input
voltage of 0 V. For the AD7714-5, the VREF voltage is +2.5 V while for the AD7714 the VREF voltage is +1.25 V. The numbers in
brackets in each table are for the effective resolution of the part (rounded to the nearest 0.5 LSB). The effective resolution of the
device is defined as the ratio of the output rms noise to the input full scale (i.e., 2 × VREF/GAIN). It should be noted that it is not
calculated using peak-to-peak output noise numbers. Peak-to-peak noise numbers 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.
2
Table III. AD7714-5 Buffered Mode Output Noise/Resolution for fCLK IN = 2.4576 MHz
Typical Output RMS Noise in V (Effective Resolution in Bits)
Filter First
Notch & O/P –3 dB
Gain of
1
Gain of
2
Gain of
4
Gain of
8
Gain of
16
Gain of
32
Gain of
64
Gain of
128
Data Rate
Frequency
5 Hz
1.31 Hz
2.62 Hz
6.55 Hz
7.86 Hz
13.1 Hz
15.72 Hz
26.2 Hz
65.5 Hz
131 Hz
262 Hz
0.99 (22.5) 0.68 (22)
0.46 (21.5) 0.26 (21) 0.26 (20)
(21.5) 0.95 (21.5) 0.63 (21) 0.41 (20.5) 0.39 (19.5) 0.36 (18.5) 0.36 (17.5) 0.36 (16.5)
(21) 1.7 (20.5) 0.88 (20.5) 0.75 (19.5) 0.57 (19)
(20.5) 1.8
(20) 2.5
(19.5) 2.9
0.26 (19) 0.26 (18) 0.26 (17)
10 Hz
25 Hz
30 Hz
50 Hz
60 Hz
100 Hz
250 Hz
500 Hz
1 kHz
1.5
2.5
2.9
4.2
6.1
0.57 (18) 0.57 (17) 0.56 (16)
0.87 (19.5) 0.75 (18.5) 0.72 (17.5) 0.72 (16.5) 0.71 (15.5)
(20.5)
(20)
(19.5)
1
(20)
1.5 (19.5) 1.1 (19) 0.94 (18.5) 0.94 (17.5) 0.94 (16.5) 0.87 (15.5)
(19.5) 1.2 (19) (18.5) 0.97 (17.5) 0.95 (16.5) 0.94 (15.5)
1.2 (17) 1.3 (16) 1.1 (15)
(15.5) 25 (15.5) 11 (15.5) 5.7 (15.5) 3.6 (15.5) 2.4 (15) 2.1 (14)
508 (13.5) 241 (13.5) 117 (13.5) 73 (13) 34 (13) 16 (13) 8.5 (13) 5.2 (13)
2860 (11) 1700 (10.5) 745 (10.5) 480 (10.5) 197 (10.5) 94 (10.5) 53 (10.5) 23 (10.5)
2
1
13.8 (18.5) 6.5
87 (16) 56
(18.5) 3.5 (18.5) 2.2 (18) 1.3 (18)
Table IV. AD7714-3 Buffered Mode Output Noise/Resolution for fCLK IN = 2.4576 MHz
Typical Output RMS Noise in V (Effective Resolution in Bits)
Filter First
Notch & O/P –3 dB
Gain of
1
Gain of
2
Gain of
4
Gain of
8
Gain of
16
Gain of
32
Gain of
64
Gain of
128
Data Rate
Frequency
5 Hz
1.31 Hz
2.62 Hz
6.55 Hz
7.86 Hz
13.1 Hz
15.72 Hz
26.2 Hz
65.5 Hz
131 Hz
262 Hz
1.16 (21)
0.76 (20.5) 0.34 (20)
0.29 (20) 0.29 (19)
0.46 (19.5) 0.45 (18.5) 0.4 (17.5) 0.4 (16.5) 0.4 (15.5)
0.74 (18.5) 0.63 (18)
0.76 (18.5) 0.68 (18)
0.28 (18) 0.26 (17) 0.26 (16)
10 Hz
25 Hz
30 Hz
50 Hz
60 Hz
100 Hz
250 Hz
500 Hz
1 kHz
1.7
3.5
3.7
4.5
5.3
10
(20.5)
(19.5) 1.8
(19.5) 2.2
(19)
(19)
(18)
1
(20.5) 0.7 (20)
(19.5) 1.1 (19)
0.6 (17) 0.6 (16) 0.6 (15)
0.66 (17) 0.66 (16) 0.66 (15)
(19)
1.3 (19)
3
(18.5) 1.7 (18.5) 1.0 (18) 0.92 (17.5) 0.9 (16.5) 0.89 (15.5) 0.89 (14.5)
3.3
4.9
(18.5) 1.8 (18.5) 1.1 (18)
(18) 3.1 (17.5) 1.5 (17.5) 1.2 (17)
(15.5) 15 (15.5) 7.5 (15.5) 4.7 (15)
74 (13) 35 (13) 21 (13)
1
(17)
0.96 (16.5) 0.96 (15.5) 0.96 (14.5)
1.2 (16) 1.2 (15) 1.2 (14)
2.6 (15) 2.5 (14) 1.6 (13.5)
8.6 (13) 5.6 (13) 3.1 (12.5)
47
(15.5) 29
300 (13.5) 171 (13)
1722 (10.5) 735 (10.5) 380 (10.5) 230 (10.5) 93 (10.5) 55 (10.5) 30 (10.5) 12 (10.5)
REV. C
–13–
ADI [ ADI ]
