Datasheet

AD7607 Data Sheet
Rev. B | Page 28 of 32
–2 –1 0
CODE
NUMBER OF OCCURANCES
1 2
2000
1800
1600
1400
1200
1000
800
600
400
200
0
AV
CC
= 5V
V
DRIVE
= 5V
T
A
= 25°C
10V RANGE
OS64
08096-130
Figure 50. Histogram of Codes, Oversampling by 64
If the OS[2:0] pins are set to select an oversampling ratio of 8,
for example, the next CONVST x rising edge takes the first sample
for each channel. The remaining seven samples for all channels
are taken with an internally generated sampling signal. As the
oversampling ratio is increased, the 3 dB frequency is reduced and
the allowed sampling frequency is also reduced (see Table 9). The
OS[2:0] pins should be configured to suit the filtering requirements
of the application.
The CONVST A and CONVST B pins must be tied/driven
together when oversampling is turned on. When the oversampling
function is turned on, the BUSY high time for the conversion
process extends. The actual BUSY high time depends on the over-
sampling rate that is selected: the higher the oversampling rate,
the longer the BUSY high or total conversion time (see Table 3).
Figure 51 shows that the conversion time extends as the over-
sampling rate is increased. To achieve the fastest throughput
rate possible when oversampling is turned on, the read can be
performed during the BUSY high time. The falling edge of BUSY
is used to update the output data registers with the new conversion
data; therefore, the reading of conversion data should not occur on
this edge.
CS
RD
DATA:
DB[15:0]
BUSY
CONVST A
AND
CONVST B
t
CYCLE
t
CONV
4µs
t
4
t
4
t
4
19µs
39µs
OS = 0 OS = 4 OS = 8
08096-044
Figure 51. No Oversampling, Oversampling by 4, and Oversampling by 8
Using Read After Conversion