AD7607 datasheet(26/32 Pages) AD

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AD7607

Data Sheet

Rev. B | Page 26 of 32

DIGITAL FILTER

The AD7607 contains an optional first-order digital sinc filter that

should be used in applications where slower throughput rates are

used and digital filtering is required. The oversampling ratio of

the digital filter is controlled using the oversampling pins, OS[2:0]

(see Table 9). OS 2 is the MSB control bit, and OS 0 is the LSB

control bit. Table 9 lists the oversampling bit decoding to select the

different oversample rates. The OS pins are latched on the falling

edge of BUSY. This sets the oversampling rate for the next

conversion (see Figure 43).

Selection of the oversampling mode has the effect of adding

a digital filter function after the ADC. The different oversampling

rates and the CONVST x sampling frequency produce different

digital filter frequency profiles.

Table 9. Oversample Bit Decoding

OS[2:0]

Oversampling Ratio

3 dB BW, 5 V Range (kHz)

3 dB BW, 10 V Range (kHz)

Maximum Throughput,

CONVST Frequency (kHz)

000

No oversampling

200

001

100

010

13.7

18.5

011

10.3

11.9

100

12.5

101

6.25

110

1.5

3.125

111

Invalid

CONVST A

AND

CONVST B

BUSY

OS x

tOS_SETUP

tOS_HOLD

CONVERSION N

CONVERSION N + 1

OVERSAMPLE RATE

LATCHED FOR CONVERSION N + 1

Figure 43. OS x Pin Timing

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