AD7760 Analog Devices, AD7760 Datasheet - Page 32

• Manufacturer Part Number: AD7760
• Description: 2.5 MSPS, 24-Bit, 100 dB Sigma-Delta ADC with On-Chip Buffer
• Manufacturer: Analog Devices

Specifications of AD7760

• Resolution (bits): 24bit
• # Chan: 1
• Sample Rate: 40MSPS
• Interface: Par
• Analog Input Type: Diff-Uni
• Ain Range: 4 V p-p,6.5 V p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: QFP

AD7760
Table 13 shows the hexadecimal values (in sign-and-magnitude
format) that are downloaded to the AD7760 to realize this filter.
The table is also split into the bytes that are summed to produce
the checksum. The checksum generated from these coefficients
is 0x0E6B.
Table 13. Filter Hexadecimal Values
Coefficient
1
2
3
4
5
6
7
8
9
10
11
12
Byte 1
03
01
00
04
04
00
00
00
04
04
04
04
Word 1
Byte 2
2B
BF
15
A8
5F
2C
50
10
2F
37
1B
04
Byte 3
96
18
66
1E
2A
49
E9
DB
DE
44
7D
3B
Word 2
Byte 4
88
3C
26
6A
96
C2
F6
D8
54
5A
6E
5F
Rev. A | Page 32 of 36
Table 14 lists the 16-bit words the user would write to the
AD7760 to set up the ADC and download this filter, assuming
an output data rate of 1.25 MHz has been selected.
Table 14. Sequence of Write Instructions to Set Up Device
and Download the Filter Example
Word
0x0001
0x8079
0x032B
0x9688
0x01BF
0x183C
…
0x0404
0x3B5F
0x0E6B
0x0001
0x0879
Description
Address of Control Register 1.
Control register data. DL filter: set filter length = 24,
set output data rate = 1.25 MHz.
First coefficient, Word 1.
First coefficient, Word 2.
Second coefficient, Word 2.
Other coefficients.
Twelfth (final) coefficient, Word 1.
Final coefficient, Word 2.
Checksum. Wait (0.5 × t
coefficients) for AD7760 to write 0s to the remaining
unused coefficients.
Address of control register.
Control register data. Set read status and maintain
filter length and decimation settings. Read contents
of status register. Check Bit 7 (DL_OK) to determine
if the filter was downloaded correctly.
Second coefficient, Word 1.
ICLK
× number of unused