Datasheet

-
+
+V
CC
= +30V
R
2
12.1 k:
V
OUT
V
REF
= +15V
R
1
20:
V
A
V
IN
V
OUT
HIGH V
OUT
LOW
R
1
V
A2
R
2
R
3
+V
CC
R
1
V
A1
R
2
R
3
+V
CC
14.975
V
IN
0
30V
V
OUT
15.025
V
A2
V
A1
-
+
+V
CC
= +30V
R
1
4.02 k:
R
2
4.02 k:
R
3
1.21 M:
V
OUT
V
IN
V
A
LM7341
www.ti.com SNOSAW9B –MAY 2008–REVISED MARCH 2013
Figure 55. Inverting Comparator with Hysteresis
NON-INVERTING COMPARATOR WITH HYSTERESIS
A non-inverting comparator with hysteresis requires a two resistor network, and a voltage reference (V
REF
) at the
inverting input. When V
IN
is low, the output is also low. For the output to switch from low to high, V
IN
must rise up
to V
IN1
where V
IN1
is calculated by
V
IN1
= R
1
*(V
REF
/R
2
) + V
REF
(4)
When V
IN
is high, the output is also high, to make the comparator switch back to it's low state, V
IN
must equal
V
REF
before V
A
will again equal V
REF
. V
IN
can be calculated by
V
IN2
= (V
REF
(R
1
+ R
2
) - V
CC
R
1
)/R
2
(5)
The hysteresis of this circuit is the difference between V
IN1
and V
IN2
.
Delta V
IN
= V
CC
R
1
/R
2
(6)
For example to achieve 50 mV of hysteresis when V
CC
= 30V set R
1
= 20Ω and R
2
= 12.1 kΩ.
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