Datasheet

DRDY
CS(DOUTwith =0)
DIN
t
CAL
CALCommand
Calibrationcomplete
andfirstdataready.
ADS1259
www.ti.com SBAS424D –JUNE 2009– REVISED AUGUST 2011
CALIBRATION The internal full-scale calibration word is bypassed
during offset calibration. Do not exceed +105% of
The ADS1259 has commands to correct for system
full-scale range for gain calibration. Note that the
offset and gain errors. Calibration can be performed
out-of-range threshold is unaffected by gain
at any time the ADS1259 and associated circuitry
calibration.
(such as the input amplifier, external reference, power
supplies, etc) have stabilized. Options include
Table 15. Calibration Timing
calibrating after power-up, after temperature changes,
t
CAL
CALIBRATION TIME (ms)
or calibration at regular intervals. To calibrate:
DATA RATE
(SPS) sinc
1
sinc
2
• Set the gate control mode (PULSE bit = 0)
14400 1.89 2.19
• Start the ADS1259 conversions
3600 5.43 6.15
• Apply the appropriate input to the ADS1259 (zero
or full-scale)
1200 14.9 16.7
• Allow time for the input to completely settle 400 43.2 48.4
60 284 318
• Send the OFSCAL (offset calibration) or GANCAL
(full-scale calibration) command, as appropriate
50 341 380
• Wait for calibration to complete as given by the
16.6 1020 1140
time listed in
Table 15
. DRDY goes low when
10 1700 1900
calibration is complete. The conversion result at
1. f
CLK
= 7.3728MHz.
this time uses the new offset or full-scale
calibration words.
Figure 56
shows the calibration timing. During
calibration, do not send commands.
Perform offset calibration prior to the gain calibration.
Figure 56. Calibration Timing
Copyright © 2009–2011, Texas Instruments Incorporated 27