LMV7239M5-NOPB Datasheet, PDF (10/22 Pages) Texas Instruments – LMV7235/LMV7239/LMV7239Q 75 nsec, Ultra Low Power, Low Voltage, Rail-to-Rail Input Comparator with Open-Drain/Push-Pull Output

LMV7235, LMV7239
SNOS532M – SEPTEMBER 2000 – REVISED FEBRUARY 2013
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When V_IN is greater than V_A (V_IN > V_A), the output voltage is low, very close to ground. In this case the three
network resistors can be presented as R2 || R3 in series with R1. The upper trip voltage V_A2 is defined as:
V_A2 = V_CC (R2||R3) / [(R1)+ (R2||R3)]
(2)
The total hysteresis provided by the network is defined as:
Delta V_A = V_A1- V_A2
(3)
To assure that the comparator will always switch fully to V_CC and not be pulled down by the load the resistors,
values should be chosen as follows:
R_PULL-UP << R_LOAD
(4)
Figure 18. 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 = R1*(V_REF / R2) + V_REF
(5)
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 (R1+ R2) - V_CC R1] / R2
(6)
The hysteresis of this circuit is the difference between V_IN1 and V_IN2.
Delta V_IN = V_CC R1 / R2
(7)
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