AD7760BCP datasheet(19/22 Pages) AD

19 / 22 page

Preliminary Technical Data

AD7760

Rev. PrN | Page 19 of 22

Table 11 shows the Hex values (in sign and magnitude format)

that are downloaded to the AD7760 to realize this filter. The

table is also split into the bytes which are all summed to

produce the checksum. The checksum generated from these

coefficients is 0x0E6B.

Table 11. Filter Hex Values

Coeff

Word 1

Word 2

Byte 1

Byte 2

Byte 3

Byte 4

What follows is a list of 16-bit words that the user would write

to the AD7760 to set up the ADC and download this filter

assuming an output data rate of 1.25MHz has already been

selected.

0x0001 Address of Control Register 1

0x8079 Control Reg Data; DL Filter, Set Filter Length = 24, Set

Output Data Rate = 1.25MHz

0x032B First Coefficient, Word 1

0x9688 First Coefficient, Word 2

0x01BF Second Coefficient, Word 1

0x183C Second Coefficient, Word 2

…

0x0404 Twelfth (Final) Coefficient, Word 1

0x3B5F Final Coefficient, Word 2

0x0E6B Checksum

Wait TBD xS for AD7760 to fill remaining unused coefficients

with zeros.

0x0001 Address of Control Register

0x0879 Control Reg 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.

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