Crystal CS5521-AP, Общее описание устройства

Страница: 26 / 38

CS5521 CS5523
26 DS317PP2
perform a system gain calibration. In either case,
the calibration signals must be within the specified
calibration limits for each specific calibration step
(refer to the System Calibration Specifications). If a system gain calibration is performed the follow-
ing conditions must be met: 1) Full-scale input
must not saturate the 20X instrumentation amplifi-
er, if the calibration is on an input range where the
instrumentation amplifier is involved. 2) The 1’s
density of the modulator must not be greater than
80 percent (the input to the
∆Σ
modulator must not
exceed the maximum input which Table 6 speci-
fies). 3) The input must not cause the resulting gain
register’s content, decoded in decimal, to exceed
3.9999998 (see the discussion of operating limits
on input span under the Analog Input and Limita-
tions in Calibration Range sections). The above
conditions require the full scale input voltage to the
modulator to be at least 25 percent of the nominal
value.
AIN+
AIN-
S1
OPEN
S2
CLOSED
+
-
X20
+
-
Figure 10. Self Calibration of Offset (Low Ranges).
AIN+
AIN-
S1
OPEN
+
-
X20
+
-
S2
OPEN
S4
CLOSED
VREF-
S3
CL
O
S
E
D
Figure 11. Self Calibration of Offset (High Ranges).
AIN+
AIN-
OPEN
+
-
X20
+
-
OPEN
CLOSED
VREF+
CLOSED
VREF-
+
-
Reference
Figure 12. Self Calibration of Gain (All Ranges).
+
-
X20
+
-
External
Connections
0V
+
-
AIN+
AIN-
CM +
-
Figure 13. System Calibration of Offset (Low Ranges).
+
-
X20
+
-
External
Connections
+
-
AIN+
AIN-
CM +
-
0V
Figure 14. System Calibration of Offset (High Ranges).
+
-
X20
+
-
External
Connections
Full Scale +
-
AIN+
AIN-
CM +
-
Figure 15. System Calibration of Gain (Low Ranges)
+
-
X20
+
-
External
Connections
Full Scale
+
-
AIN+
AIN-
CM
+
-
Figure 16. System Calibration of Gain (High Ranges).