AD7707 Просмотр технического описания (PDF) - Analog Devices
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AD7707 Datasheet PDF : 40 Pages
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AD7707
Table VI. Output RMS Noise/ Peak-to-Peak Resolution vs. Gain and Output Update Rate @ +5 V
AIN3 Buffered Mode Only
Filter First
؎10 V Range
؎5 V Range
0 V to +10 V Range
0 to +5 V Range
Notch and O/P –3␣ dB
RMS Noise P-P (Bits) RMS Noise P-P (Bits) RMS Noise P-P (Bits) RMS Noise P-P (Bits)
Data Rate
Frequency (V)
Resolution (V)
Resolution (V)
Resolution (V)
Resolution
MCLK IN = 2.4576 MHz
10␣ Hz
2.62␣ Hz 7.4
16
5.2
16
7.4
16
50␣ Hz
13.1␣ Hz 22.2
16
14.3
16
22.2
16
60␣ Hz
15.72␣ Hz 26.6
16
15.85
16
26.6
16
250␣ Hz
65.5␣ Hz 475
13
187
13
475
12
500␣ Hz
131␣ Hz
2423
10.5
1097
10.5
2423
9.5
5.2
16
14.3
16
15.85
16
187
12
1097
9.5
MCLK IN = 1 MHz
4.05␣ Hz
1.06␣ Hz 7.63
16
5.45
16
7.63
16
20␣ Hz
5.24␣ Hz 20.25
16
13.3
16
20.25
16
25␣ Hz
6.55␣ Hz 23.5
16
14.6
16
23.5
16
100␣ Hz
26.2␣ Hz 377
13
210
13
377
12
200␣ Hz
52.4␣ Hz 2226
10.5
1132
10.5
2226
9.5
5.45
16
13.3
16
14.6
15.5
210
12
1132
9.5
OUTPUT NOISE FOR HIGH LEVEL INPUT CHANNEL AIN3 (5 V OPERATION)
Table VII shows the AD7707 output rms noise and peak-to-peak resolution for the selectable notch and –3␣ dB frequencies for the
part, as selected by FS0, FS1 and FS2 of the Clock Register. The numbers given are for the ± 5 V, 0 V to +5 V and 0 V to +10 V
ranges with a VREF of +1.225 V, HBIAS = 1.225 V, HICOM = AGND and AVDD = 3 V. These numbers are typical and are gener-
ated at an analog input voltage of 0 V for unbuffered mode of operation. The above operating ranges are only achievable in unbuf-
fered mode when operating at 3 V due to common-mode limitations on the input amplifier. It is important to note that these numbers
represent the resolution for which there will be no code flicker. They are not calculated based on rms noise but on peak-to-peak noise. Operating
at a gain of 1 in unipolar mode provides a range of 0 V to +10 V. Operating the high level channel with a gain of 2 in bipolar mode
provides a ± 5 V operating range. Operating at a gain of 2 in unipolar mode provides an operating range of 0 V to +5 V. The output
noise comes from two sources. The first is the electrical noise in the semiconductor devices (device noise) used in the implementation
of the modulator. Secondly, when the analog input is converted into the digital domain, quantization noise is added. The device
noise is at a low level and is independent of frequency. The quantization noise starts at an even lower level but rises rapidly with
increasing frequency to become the dominant noise source. The numbers in the tables are given for the bipolar input ranges. For the
unipolar ranges the rms noise numbers will be the same as the bipolar range but the peak-to-peak resolution is now based on half the
signal range which effectively means losing 1 bit of resolution.
Table VII. Output RMS Noise/ Peak-to-Peak Resolution vs. Gain and Output Update Rate @ +3 V
AIN3 Unbuffered Mode Only
Filter First
Notch and O/P
Data Rate
–3␣ dB
Frequency
MCLK IN = 2.4576 MHz
10␣ Hz
2.62␣ Hz
50␣ Hz
13.1␣ Hz
60␣ Hz
15.72␣ Hz
250␣ Hz
65.5␣ Hz
500␣ Hz
131␣ Hz
MCLK IN = 1 MHz
4.05␣ Hz
1.06␣ Hz
20␣ Hz
5.24␣ Hz
25␣ Hz
6.55␣ Hz
100␣ Hz
26.2␣ Hz
200␣ Hz
52.4␣ Hz
0 V to +10 V Range
RMS Noise P-P (Bits)
(V)
Resolution
12.4
16
30.35
16
34.55
16
498
12.5
2266
10.5
13.9
16
32.2
16
33.4
16
430
13
2207
10.5
؎5 V Range
RMS Noise P-P (Bits)
(V)
Resolution
0 to +5 V Range
RMS Noise P-P (Bits)
(V)
Resolution
7.02
16
16.4
16
19.13
16
204
13
1151
10.5
7.02
16
16.4
15.5
19.13
15
204
12
1151
9.5
7.3
16
17.4
16
18.57
16
200
13
1048
10.5
7.3
16
17.4
15
18.57
15
200
12
1048
9.5
REV. A
–11–
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