AD7707 Analog Devices, AD7707 Datasheet - Page 48

• Manufacturer Part Number: AD7707
• Manufacturer: Analog Devices

Specifications of AD7707

• Resolution (bits): 16bit
• # Chan: 3
• Sample Rate: n/a
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni,SE-Bip
• Ain Range: Bip (Vref)/(PGA Gain),Bip 10V,Bip 5.0V,Uni (Vref)/(PGA Gain),Uni 10V,Uni 5.0V
• Adc Architecture: Sigma-Delta
• Pkg Type: SOIC,SOP

AD7707
3 V OPERATION
Table 33 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 are given for all input ranges with a V
= 1.25 V, HICOM = AGND, and AV
are typical and are generated at an analog input voltage of 0 V
for unbuffered mode of operation. Table 34 meanwhile shows
the output rms noise and peak-to-peak resolution for buffered
mode of operation with the same operating conditions as for
Table 33. It is important to note that these numbers represent
the resolution for which there is no code flicker. They are not
calculated based on rms noise but on peak-to-peak noise. The
Table 33. AIN3, Output RMS Noise/Peak-to-Peak Resolution vs. Gain and Output Update Rate @ +3 V Unbuffered Mode
Filter First
Notch and
Output Data
Rate
MCLK IN = 2.4576 MHz
10 Hz
50 Hz
60 Hz
250 Hz
500 Hz
Table 34. AIN3, Output RMS Noise/Peak-to-Peak Resolution vs. Gain and Output Update Rate @ +3 V Buffered Mode
Filter First
Notch and
Output Data
Rate
MCLK IN = 2.4576 MHz
10 Hz
50 Hz
60 Hz
250 Hz
500 Hz
−3 dB
Frequency
2.62 Hz
13.1 Hz
15.72 Hz
65.5 Hz
131 Hz
−3 dB
Frequency
2.62 Hz
13.1 Hz
15.72 Hz
65.5 Hz
131 Hz
Gain of 1
12.4 (16)
30.35 (16)
34.55 (16)
498 (13)
2266 (10.5)
Gain of 1
14.84 (16)
36.1 (16)
38.8 (16)
420 (13)
2234 (10.5)
DD
= 3 V. These numbers
8.39 (16)
Gain of 2
18.8 (16)
21.55 (16)
194 (13)
1231 (10.5)
Gain of 2
7.02 (16)
16.4 (16)
19.13 (16)
204 (13)
1151 (10.5)
REF
of 1.25 V, HBIAS
Typical Output RMS Noise in μV (Peak-to-Peak Resolution)
Gain of 4
3.87 (16)
9.4 (16)
10.9 (16)
105 (13)
554 (10.5)
Gain of 4
5.56 (16)
11.5 (16)
13.39 (16)
97.6 (13)
534 (10.5)
Typical Output RMS Noise in μV (Peak-to-Peak Resolution)
Rev. B | Page 48 of 52
Gain of 8
2.41 (16)
5.85 (16)
6 (16)
57.5 (13)
280 (10.5)
Gain of 8
3.45 (16)
7.5 (15.5)
8.5 (15.5)
54.5 (12.5)
275 (10.5)
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 Table 33 and Table 34 are given
for the bipolar input ranges. For the unipolar ranges, the rms
noise numbers are 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.
Gain of 16
2.39 (16)
5.2 (15)
5.8 (15)
27.5 (13)
136 (10.5)
Gain of 16
3.3 (16)
7.4 (14.5)
8.36 (14.5)
30 (12.5)
145 (10.5)
Gain of 32
2.3 (15.5)
4.5 (14.5)
5.62 (14)
17.4 (12.5)
83 (10)
Gain of 32
3.2 (15)
7.43 (13.5)
8 (13.5)
22 (12)
71 (10.5)
Gain of 64
2.29 (14.5)
4.5 (13.5)
5.2 (13)
12.7 (12)
39 (10)
Gain of 64
3.2 (14)
6.8 (12.5)
8.2 (12.5)
18 (11.5)
48 (10)
Gain of 128
3.3 (13)
7 (12)
7.7 (12)
16.7 (10.5)
31 (9.5)
Gain of 128
2.13 (13.5)
5.09 (12)
6.14 (12)
11.42 (11)
27.5 (9.5)