LMP8358MA NSC [National Semiconductor], LMP8358MA Datasheet - Page 25

• Manufacturer Part Number: LMP8358MA
• Description: Zero-Drift, Programmable Instrumentation Amplifier with Diagnostics
• Manufacturer: NSC [National Semiconductor]

FAULT DETECTION METHODS
Using the Multiplexer, Polarity, and Current features the end
user can detect faults in the system between the sensor and
the LMP8358. These examples will use the set up shown in
Common Mode Out of Range
Figure 8
tween the bottom of the bridge and ground. This fault is shown
by the 1.5 kΩ resistor placed between the bridge and ground.
This will raise the common mode at the inputs of the LMP8358
to 4V, which is out of the CMVR. To determine the common
shows an example of a degraded connection be-
FIGURE 8. Degraded Connection Between the Bottom of the Bridge and Ground
FIGURE 7. Bridge Connected to the LMP8358 With No Problems
25
Figure 7
some cabling to a supply and the LMP8358. The fault detec-
tion methods are described below.
mode voltage at the input pins, use the 1/50 feature by setting
MUX[1:0] to 10b to test the +IN pin or to 11b to test the −IN
pin, POL to 0b, and G[2:0] to 010b for a gain of 50 (0082x or
00C2x). This will give an overall gain of 1 and the output will
read 4V for either MUX setting.
which shows a bridge sensor connected through
300454b5
300454b6
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