Datasheet

Fault Windows Scaled Independently
Fault window for the Sense Input,
in percent, is:
–
10 (V
ADJ
)
•
R
3
+
R
1
R
2
/
(
R
1
+
R
2
)
R
3
,
for:
V
S
(
NOM
)
•
R
2
R
1
+
R
2
=2.5V
Monitored
SupplyVoltage
V
S
R1
R2
R3
UC1903
SENSE1-4INPUT
2.5V
REF.
Fault window for the sense input, in percent, is:
•
R
2
R
1
+
R
2
SENSE
INPUT
R1
R2
UC1903
G.P.OP-AMP
2.5V
REF.
SENSE1-4INPUT
±10(V )
ADJ
UC1903
UC2903
UC3903
www.ti.com ........................................................................................................................................ SLUS233A – OCTOBER 1999 – REVISED SEPTEMBER 2008
In many applications, it may be desirable to monitor various supply voltages, or voltage levels, with varying fault
windows. Using the reference output and external resistive dividers this is easily accomplished with the UC1903.
Figure 3 and Figure 4 illustrate how the fault window at any sense input can be scaled independently of the
remaining inputs.
A. Using the reference output and a resistive divider, a sense input with an independently wider fault window can be
generated.
Figure 3. UC1903 Sense Input with an Independently Wider Fault Window
A. The general purpose op-amp on the UC1903 can be used to create a sense input with an independently tighter fault
window.
Figure 4. UC1903 Sense Input with an Independently Tighter Fault Window
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Product Folder Link(s): UC1903 UC2903 UC3903