AD7714YN Analog Devices Inc, AD7714YN Datasheet - Page 12

• Manufacturer Part Number: AD7714YN
• Description: IC ADC 24BIT SIGMA-DELTA 24-DIP
• Manufacturer: Analog Devices Inc

Specifications of AD7714YN

• Rohs Status: RoHS non-compliant
• Number Of Bits: 24
• Sampling Rate (per Second): 1k
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 7mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Through Hole
• Package / Case: 24-DIP (0.300", 7.62mm)
• For Use With: EVAL-AD7714-3EBZ - BOARD EVALUATION FOR AD7714

AD7714-3 OUTPUT NOISE
Table IIa shows the output rms noise and effective resolution for some typical notch and –3 dB frequencies for the AD7714-3 with
f
ranges with a 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 V
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.
The output noise from the part comes from two sources. The first is the electrical noise in the semiconductor devices used in the
implementation of the modulator (device noise). Secondly, when the analog input signal is converted into the digital domain, quan-
tization noise is added. The device noise is at a low level and is largely independent of frequency. The quantization noise starts at
an even lower level but rises rapidly with increasing frequency to become the dominant noise source. Consequently, lower filter
notch settings (below 100 Hz approximately for f
be device noise dominated while higher notch settings are dominated by quantization noise. Changing the filter notch and cutoff
frequency in the quantization noise dominated region results in a more dramatic improvement in noise performance than it does in
the device-noise dominated region as shown in Table II. Furthermore, quantization noise is added after the PGA, so effective reso-
lution is largely independent of gain for the higher filter notch frequencies. Meanwhile, device noise is added in the PGA and, there-
fore, effective resolution suffers a little at high gains for lower notch frequencies. Additionally, in the device-noise dominated region,
the output noise (in V) is largely independent of reference voltage while in the quantization-noise dominated region, the noise is
proportional to the value of the reference. It is possible to do post-filtering on the device to improve the output data rate for a given
–3 dB frequency and also to further reduce the output noise.
At the lower filter notch settings (below 60 Hz for f
codes performance of the device is at the 24-bit level. At the higher settings, more codes will be missed until at 1 kHz notch setting
for f
AD7714
Filter First
Notch & O/P –3 dB
Data Rate
5 Hz
10 Hz
25 Hz
30 Hz
50 Hz
60 Hz
100 Hz
250 Hz
500 Hz
1 kHz
Filter First
Notch & O/P –3 dB
Data Rate
2 Hz
4 Hz
10 Hz
25 Hz
30 Hz
50 Hz
60 Hz
100 Hz
200 Hz
400 Hz
CLK IN
CLK IN
= 2.4576 MHz while Table IIb gives the information for f
= 2.4576 MHz (400 Hz for f
Table IIa. AD7714-3 Output Noise/Resolution vs. Gain and First Notch for f
Table IIb. AD7714-3 Output Noise/Resolution vs. Gain and First Notch for f
REF
Frequency
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
Frequency
0.52 Hz
1.05 Hz
2.62 Hz
6.55 Hz
7.86 Hz
13.1 Hz
15.72 Hz
26.2 Hz
52.4 Hz
104.8 Hz
of +1.25 V and BUFFER = 0. These numbers are typical and are generated at an analog input voltage of 0 V.
1.07
1.69
3.03
3.55
4.72
5.12
9.68
44
304
1410 (11)
0.86
1.26
1.68
3.82
4.88
11
14.7
61
275
1435 (11)
Gain of
Gain of
1
1
(21)
(20.5) 1.1
(19.5) 1.7
(19.5) 2.1
(19)
(19)
(18)
(16)
(13)
(21.5) 0.58 (21)
(21)
(20.5) 1.33 (20)
(19.5) 2.0
(19)
(18)
(17.5) 7.5
(15.5) 30
(13)
CLK IN
0.68 (21)
2.3
3.1
5.6
31
129
715
0.74 (20.5) 0.44 (20.5) 0.35 (20)
2.1
4.8
130
720
Gain of
Gain of
= 1 MHz), no missing codes performance is only guaranteed to the 12-bit level.
2
2
CLK IN
Typical Output RMS Noise in V (Effective Resolution in Bits)
(20)
(19.5) 0.89 (19.5) 0.55 (19)
(19)
(19)
(18.5) 1.6 (18)
(18)
(15.5) 15
(13)
(11)
Typical Output RMS Noise in V (Effective Resolution in Bits)
(19.5) 1.2 (19)
(19)
(18)
(17.5) 3.8 (17.5) 2.6 (17)
(15.5) 12
(13)
(11)
CLK IN
= 2.4576 MHz and below 40 Hz approximately for f
0.29 (21)
0.56 (20)
1.1 (19)
1.5 (18.5) 0.84 (18.5) 0.7 (18)
2.4 (18)
76
350 (11)
= 2.4576 MHz and below 25 Hz for f
0.32 (21)
0.73 (20)
1.3 (19)
2.4 (18)
65
362 (11)
Gain of
Gain of
4
4
(15.5) 5.8 (15.5) 3.7 (15.5) 2.4 (15)
(13)
(15.5) 6.1 (15.5) 2.9 (15.5) 2.4 (15)
(13)
–12–
CLK IN
0.24 (20)
0.35 (19.5) 0.33 (19)
0.61 (18.5) 0.58 (18)
0.98 (18)
1.3 (18)
33
177 (11)
0.21 (20.5) 0.2 (19.5) 0.2 (18.5) 0.2 (17.5) 0.2 (16.5)
0.5 (19)
0.88 (18.5) 0.66 (18)
0.93 (18.5) 0.82 (17.5) 0.69 (17)
1.4 (18)
33
175 (11)
Gain of
Gain of
= 1 MHz. The numbers given are for the bipolar input
8
8
(13)
(13)
0.22 (19.5) 0.22 (18.5) 0.22 (17.5) 0.22 (16.5)
0.49 (18.5) 0.46 (17.5) 0.46 (16.5) 0.45 (15.5)
0.9 (17.5) 0.7 (17)
1.1 (17)
20
101 (10.5) 51
0.49 (18.5) 0.49 (17.5) 0.48 (16.5) 0.47 (15.5)
1.4 (17)
1.5 (16.5) 0.95 (16.5) 0.88 (15)
110 (10.5) 51
0.3 (19)
17
Gain of
Gain of
16
16
CLK IN
(13)
(13)
CLK IN
= 2.4576 MHz, BUFFER = 0
CLK IN
0.33 (18)
0.57 (17)
0.68 (17)
0.95 (16.5) 0.88 (15.5) 0.9 (14.5)
11
0.3 (18)
0.57 (17)
0.73 (16.5) 0.71 (15.5) 0.7 (15)
11
= 1 MHz, BUFFER = 0
Gain of
Gain of
32
32
= 1 MHz), the no missing
(13)
(10.5) 31
(13)
(10.5) 31
REF
/GAIN). It should be
CLK IN
0.33 (17)
0.55 (16)
0.67 (16)
0.69 (16)
0.55 (16)
0.68 (16)
1.8 (14.5) 1.8 (13.5)
6.3 (12.5) 3
0.3 (17)
1.8 (14.5) 1.8 (13.5)
6.3 (12.5) 3
Gain of
Gain of
64
64
(10.5) 12
(10.5) 12
= 1 MHz) tend to
0.33 (16)
0.55 (15)
0.66 (15)
0.68 (15)
0.3 (16)
0.55 (15)
0.66 (15)
0.9 (14.5)
Gain of
Gain of
128
128
REV. C
(12.5)
(10.5)
(12.5)
(10.5)