+
-
900 kΩ
100 kΩ
U
diff
.
IN(+)
IN(-)
Isolated
channel
Non-isolated
system
Single-ended, isolated
ADC
10 * U
diff
.
Passive HV probe
900 kΩ
100 kΩ
U
iso
Figure 12.29:
Input channel with a high voltage 10:1 passive probe
12.3.6
GN815 and GN816 Input overload protection
The input section has several methods to protect against voltage overload on
the input.
Every selected input range allows a 200% overload without any change of input
resistance or auto ranging. This 200% overrange is designed to allow for
smaller voltage overloads without affecting the measurement. Within this
200% overload, the amplifier is also able to respond with normal rise/fall times
and the signal is restored within the standard selected range.
When exceeding the 200% overload, the input channel might start to take
protective actions.
+
-
U
iso
Isolated
channel
Non-isolated
system
Single-ended, isolated
ADC
IEPE
GND AC/DC
+12 V
-12 V
/1 /10
Figure 12.30:
Input overload protection
-
Schematic diagram
The
first
action of the system is to add an additional current load to the input
signal to create an extra voltage drop in the input series resistance. The
resulting additional current depends on several factors and is therefore
unpredictable. A negative side effect of this additional current is that the extra
power is dissipated in the input section, which in turn results in additional heat
dissipation.
GEN3i
246
I3763-3.1 en HBM: public
