Datasheet
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last update
November 30, 2010
reference
smtutin
page
22/27
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In this mode, a resistive bridge can be measured where the physical signal is represented by the output
voltage of the bridge and the current through the bridge. This current I is converted into a reference
voltage. The connection of the bridge and the reference element is shown in
Figure 14(a).
The value of
R
ref
should be chosen such that V
AB
is between 0.1 V and 0.2 V.
This mode can also be used to
measure platinum resistors in a 4-wire setup. This is shown in
Figure 14(b).
The advantage in comparison
with mode Pt is that now only three phases have to be measured.
a) b)
Figure 14. Connection of the resistive bridge and a reference resistor to the UTI (a) and connection of a
platinum resistor in 4-wire setup (b)
Parameter (V
DD
= 5 V) Typical value
K
2
56 s/V
V
0
0.54 V
Bridge excitation AC Vdd
excitation current (max E - F) 20 mA
Bridge resistance 250-10k
Bridge output Voltage <+/- 12,5 mV
Accuracy 10 bits (over =/- 0.2V)
Offset
<10 V
Resolution (SF=0) < 700 nV
Table 19. Specifications of the Ub1 mode
E
C
D
A
B
F
UTI
R
bias
Pt100
E
C
D
A
B
F