Datasheet

V
+
V
REF2
V
REF1
BOTH OUTPUTS
ARE HIGH
OUTPUT A
OUTPUT B
V
IN
V
+
R
1
R
2
R
3
-
+
-
+
OUTPUT A
OUTPUT B
V
REF2
V
REF1
A
B
V
IN
LPV7215
SNOSAI6I –SEPTEMBER 2005–REVISED APRIL 2013 www.ti.com
The capacitor C
1
now discharges through R
4
, and the voltage V
C
decreases until it is equal to V
A2
, at which point
the comparator switches again, bringing it back to the initial stage. The time period is equal to twice the time it
takes to discharge C
1
from 2V
CC
/3 to V
CC
/3, which is given by R
4
C
1
·ln2. Hence the formula for the frequency is:
F = 1/(2·R
4
·C
1
·ln2)
WINDOW DETECTOR
A window detector monitors the input signal to determine if it falls between two voltage levels.
The comparator outputs A and B are high only when
V
REF1
< V
IN
< V
REF2
“or within the window.”
where these are defined as
V
REF1
= R
3
/(R
1
+R
2
+R
3
) * V
+
V
REF2
= (R
2
+R
3
)/(R
1
+R
2
+R
3
) * V
+
(1)
Others names for window detectors are: threshold detector, level detectors, and amplitude trigger or detector.
Figure 42. Window Detector
Figure 43. Window Detector Output Signal
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