AD7607 datasheet(28/32 Pages) AD

28 / 32 page

AD7607

Data Sheet

Rev. B | Page 28 of 32

–2

–1

CODE

2000

1800

1600

1400

1200

1000

800

600

400

200

AVCC = 5V

VDRIVE = 5V

TA = 25°C

10V RANGE

OS64

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.

DATA:

DB[15:0]

BUSY

CONVST A

AND

CONVST B

tCYCLE

tCONV

4µs

19µs

39µs

OS = 0 OS = 4 OS = 8

Figure 51. No Oversampling, Oversampling by 4, and Oversampling by 8

Using Read After Conversion

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