Datasheet

V
A2
=
V
CC
(R
2
||R
3
)
R
1
+ (R
2
||R
3
)
V
A1
=
V
CC
R
2
(R
1
||R
3
) + R
2
LMV7291
SNOSA86E –FEBRUARY 2004–REVISED MARCH 2013 www.ti.com
(1)
When V
IN
is greater than V
A
(V
IN
> V
A
), the output voltage is low and very close to ground. In this case the three
network resistors can be presented as R
2
//R
3
in series with R
1
. The upper trip voltage V
A2
is defined as
(2)
The total hysteresis provided by the network is defined as
ΔV
A
= V
A1
- V
A2
(3)
A good typical value of ΔV
A
would be in the range of 5 to 50 mV. This is easily obtained by choosing R
3
as 1000
to 100 times (R
1
||R
2
) for 5V operation, or as 300 to 30 times (R
1
||R
2
) for 1.8V operation.
Figure 27. 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 (Figure 28). 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
(4)
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