Current Pca (A7) - Fluke 5080A Service Manual

Current PCA (A7)

The Current PCA outputs six current ranges (330 μA, 3.3 mA, 33 mA, 330 mA,
3 A, and 20 A) and three voltage ranges (330 mV, 3.3 V, and 5 V) to the AUX
outputs. The 20 A outputs are sourced through the 20 A AUX binding posts.
The Current PCA connects to the DDS PCA (A6). The Filter PCA (A12) supplies
the high current power supplies.
The Current PCA (A7) has these functional blocks:
•
Transconductance amplifier.
•
Precision current shunts and amplifier. (These are the elements that set
accuracy.)
•
AUX voltage function.
Power for the Current PCA is provided by the Filter PCA (A12).
Figure 5 is a block diagram of the current function. Note that the DDS PCA works
together with the Current PCA to supply current outputs.
DDS PCA (A6)
IDAC
Ref
±
SCOM
DDS
IDAC Error
Ch 1
Amp
dc
AC
ac
Converter
Figure 5. Current Function (AUX Out Ranges)
Current PCA (A7)
Current
Amp
ac
dc
SCOM
Shunt
Amp
SCOM
Calibrator
Theory of Operation
AUX HI
AUX LO
SCOM
Shunt
ICOM
yg119f.eps
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