Datasheet

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 15 22 200
001 2 15 22 100
010 4 13.7 18.5 50
011 8 10.3 11.9 25
100 16 6 6 12.5
101 32 3 3 6.25
110 64 1.5 1.5 3.125
111 Invalid
CONVST A
AND
CONVST B
BUSY
OS x
t
OS_SETUP
t
OS_HOLD
CONVERSION N CONVERSION N + 1
OVERSAMPLE RATE
LATCHED FOR CONVERSION N + 1
08096-043
Figure 43. OS x Pin Timing