AD7762 Analog Devices, AD7762 Datasheet - Page 22

• Manufacturer Part Number: AD7762
• Description: Parallel Interface, 625 kSPS, 24-Bit Sigma-Delta A/D Converter
• Manufacturer: Analog Devices

Specifications of AD7762

• Resolution (bits): 24bit
• # Chan: 1
• Sample Rate: 40MSPS
• Interface: Par
• Analog Input Type: Diff-Uni
• Ain Range: (1.6Vref) p-p,4 V p-p,6.5 V p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: QFP

AD7762
Table 13 shows the hex values (in sign and magnitude format)
that are downloaded to the AD7762 to realize this filter. The
table is also split into the bytes that are all summed to produce
the checksum. The checksum generated from these coefficients
is 0x0E6B.
Table 13. Filter Hex 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. 0 | Page 22 of 28
Table 14 lists the 16-bit words the user would write to the
AD7762 to set up the ADC and download this filter, assuming
an output data rate of 625 kHz has already been selected.
Table 14.
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 = 625 kHz.
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 AD7762 to fill remaining unused
coefficients with 0s.
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
that the filter was downloaded correctly.
Second coefficient, Word 1.
ICLK
× Number of Unused