Datasheet

AD7715
Rev. D | Page 25 of 40
If the part is used in unipolar mode with a required span of
0.8 × V
REF
/GAIN, then the offset range which the system
calibration can handle is from −1.05 × V
REF
/GAIN to +0.25 ×
V
REF
/GAIN. If the part is used in unipolar mode with a required
span of V
REF
/GAIN, then the offset range which the system
calibration can handle is from −1.05 × V
REF
/GAIN to +0.05 ×
V
REF
/GAIN. Similarly, if the part is used in unipolar mode and
required to remove an offset of 0.2 × V
REF
/GAIN, then the span
range which the system calibration can handle is 0.85 ×
V
REF
/GAIN.
If the part is used in bipolar mode with a required span of ±0.4 ×
V
REF
/GAIN, then the offset range which the system calibration
can handle is from −0.65 × V
REF
/GAIN to +0.65 × V
REF
/GAIN. If
the part is used in bipolar mode with a required span of ±V
REF
/
GAIN, then the offset range which the system calibration can
handle is from −0.05 × V
REF
/GAIN to +0.05 × V
REF
/GAIN.
Similarly, if the part is used in bipolar mode and required to
remove an offset of ±0.2 × V
REF
/GAIN, then the span range
which the system calibration can handle is ±0.85 × V
REF
/GAIN.
Power-Up and Calibration
On power-up, the AD7715 performs an internal reset that sets
the contents of the internal registers to a known state. There are
default values loaded to all registers after a power-on or reset.
The default values contain nominal calibration coefficients for
the calibration registers. However, to ensure correct calibration
for the device a calibration routine should be performed after
power-up.
The power dissipation and temperature drift of the AD7715
are low, and no warm-up time is required before the initial
calibration is performed. However, if an external reference is
being used, this reference must have stabilized before calibration is
initiated. Similarly, if the clock source for the part is generated
from a crystal or resonator across the MCLK pins, the start-up
time for the oscillator circuit should elapse before a calibration
is initiated on the part (see the Clocking and Oscillator Circuit
section).