Datasheet

REV. 0
–14–
AD7708/AD7718
READING NUMBER
8389600
8389400
8388000
0 1000100
CODE READ
200 300
8389200
400 500 600 700 800 900
8389000
8388800
8388600
8388400
8388200
AV
DD
= DV
DD
= 5V
INPUT RANGE = ⴞ20mV
REFIN1(+)–REFIN1(–) = 2.5V
UPDATE RATE = 19.79Hz
T
A
= 25ⴗC
V
REF
= 2.5V
RMS NOISE = 0.58␮V rms
TPC 1. AD7718 Typical Noise Plot on ± 20 mV Input Range
with 19.79 Hz Update Rate
8
7
0
8388039
8388721
8388687 8388657
8388615
8388579
8388547
8388499 8388449
8388382
8388754
8389110
8389033 8388985 8388941
8388906
8388874
8388841 8388805
8388779
6
5
4
3
2
1
9
TPC 2. AD7718 Noise Distribution Histogram
2.5
0
1.0 3.02.52.01.5 3.5 5.04.54.0
2.0
1.5
1.0
0.5
3.0
V
REF
– V
RMS NOISE – ␮V
ⴞ20mV RANGE
ⴞ2.56V RANGE
AV
DD
= DV
DD
= 5V
V
REF
= 2.5V
INPUT RANGE = ⴞ2.56V
UPDATE RATE = 19.79Hz
T
A
= 25ⴗC
TPC 3. RMS Noise vs. Reference Input
(AD7718 andAD7708)
16
040302010 50 10090807060
24
22
20
18
26
UPDATE RATE – Hz
NO MISSING CODES – Min
110
CHOP = 0
TPC 4. AD7718 No-Missing Codes Performance
32767
1000 200 400300
32771
32770
32769
32768
32772
READING NUMBER
CODE READ
500
32766
32765
32764
600 700 800 900 1000
AV
DD
= DV
DD
= 5V
INPUT RANGE = ⴞ20mV
UPDATE RATE = 19.79Hz
V
REF
= 2.5V
T
A
= 25 C
TPC 5. AD7708 Typical Noise Plot on ± 20 mV Input Range
200
3276732766 32768 3277032769
600
500
400
300
700
CODE
OCCURRENCE
32771
100
0
TPC 6. AD7708 Noise Histogram
–Typical Performance Characteristics