Datasheet

AD7762 Data Sheet
Rev. A | Page 22 of 28
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
Word 1 Word 2
Coefficient
Byte 1
Byte 2
Byte 3
Byte 4
1 03 2B 96 88
2
01
BF
18
3C
3 00 15 66 26
4 04 A8 1E 6A
5 04 5F 2A 96
6 00 2C 49 C2
7 00 50 E9 F6
8 00 10 DB D8
9 04 2F DE 54
10 04 37 44 5A
11 04 1B 7D 6E
12 04 04 3B 5F
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 Description
0x0001 Address of Control Register 1.
0x8079
Control register data. DL filter, set filter length = 24,
set output data rate = 625 kHz.
0x032B First coefficient, Word 1.
0x9688 First coefficient, Word 2.
0x01BF Second coefficient, Word 1.
0x183C Second coefficient, Word 2.
…
Other coefficients.
0x0404 Twelfth (final) coefficient, Word 1.
0x3B5F Final coefficient, Word 2.
0x0E6B
Checksum. Wait (0.5 × t
ICLK
× Number of Unused
Coefficients) for AD7762 to fill remaining unused
coefficients with 0s.
0x0001 Address of control register.
0x0879
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.