Datasheet

OffsetDrift=
V V-
OFFMAX OFFMIN
TempRange
GainDrift=
GainError Gain-
MAX MIN
Error
TempRange
DRDY
V =AINP -
IN
AINN
DOUT
OldV Data
IN
Settled
Data
FullySettled
NewV Data
IN
Mixof
OldandNew
V Data
IN
OldVIN
NewV
IN
t
SET
ADS1259
www.ti.com SBAS424D –JUNE 2009– REVISED AUGUST 2011
Settling Time While Continuously Converting
OFFSET AND GAIN
If there is a step change on the input signal while
The ADS1259 features low offset (40μV, typ) and low
continuously converting, the next data represent a
gain errors (0.05%, typ). The offset and gain errors
combination of the previous and current input signal
can be corrected by sending calibration commands to
and should therefore be discarded; see Figure 54 for
the ADS1259; see the Calibration section.
this step change. Table 10 shows the number of
The ADS1259 also features very low offset drift
conversion cycles for completely settled data while
(0.05μV/°C, typ) and very low gain drift (0.5ppm/°C,
continuously converting.
typ). The offset and gain drift are calculated using the
box method, as described by Equation 6 and
Table 10. Settling Time While Continuously
Equation 7:
Converting DRDY Periods
(1)
SETTLING TIME (t
SET
) (Conversions)
DATA RATE
(SPS)
sinc
1
sinc
2
(6)
10 2 3
16.6 2 3
50 2 3
60 2 3
where:
400 2 3
V
OFFMAX
, V
OFFMIN
, GainError
MAX
, and GainError
MIN
1200 2 3
are the maximum and minimum offset and gain
error readings recorded over the Temp Range
3600 3 4
(–40°C to +105°C) (7)
14,400 6 7
(1) Settling time is defined as the number of DRDY periods after
the input signal has settled following an input step change.
For best data throughput in multiplexed applications, issue a
START condition (START pin or Start command) after the
input has settled following a multiplexer change; see the
Setling Time Using START section.
Figure 54. Step Change on V
IN
while Continuously Converting
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