ADS1259
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SBAS424C –JUNE 2009–REVISED MARCH 2010
CALIBRATION
The internal full-scale calibration word is bypassed
during offset calibration. Do not exceed +105% of
full-scale range for gain calibration. Note that the
out-of-range threshold is unaffected by gain
calibration.
The ADS1259 has commands to correct for system
offset and gain errors. Calibration can be performed
at any time the ADS1259 and associated circuitry
(such as the input amplifier, external reference, power
supplies, etc) have stabilized. Options include
calibrating after power-up, after temperature changes,
or calibration at regular intervals. To calibrate:
Table 15. Calibration Timing
tCAL CALIBRATION TIME (ms)
DATA RATE
(SPS)
14400
3600
1200
400
sinc1
1.89
5.43
14.9
43.2
284
sinc2
2.19
6.15
16.7
48.4
318
•
•
•
Set the gate control mode (PULSE bit = 0)
Start the ADS1259 conversions
Apply the appropriate input to the ADS1259 (zero
or full-scale)
Allow time for the input to completely settle
Send the OFSCAL (offset calibration) or GANCAL
(full-scale calibration) command, as appropriate
•
•
60
50
341
380
•
Wait for calibration to complete as given by the
time listed in
calibration is complete. The conversion result at
this time uses the new offset or full-scale
calibration words.
16.6
10
1020
1700
1140
1900
Table
15. DRDY goes low when
1. fCLK = 7.3728MHz.
Figure
55
DRDY
(DOUT with CS = 0)
shows the calibration timing. During
tCAL
calibration, do not send commands.
Calibration complete
and first data ready.
Perform offset calibration prior to the gain calibration.
CAL Command
DIN
Figure 55. Calibration Timing
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