LMV7275-Q1

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SNOSD09 – SEPTEMBER 2015

Feature Description (continued)

7.3.2 Output Stage

Figure 19. LMV7275-Q1 Open-Drain Output

The LMV7275-Q1 has an open-drain output that requires a pull-up resistor to a positive supply voltage for the

output to operate properly. When the internal output transistor is off, the output voltage will be pulled up to the

open-drain outputs on the same bus.

The output pull-up resistor may be connected to any voltage level between V- and V+ for level shifting

applications.

7.4 Device Functional Modes

7.4.1 Capacitive and Resistive Loads

The propagation delay on the rising edge of the LMV7275-Q1 depends on the load resistance and capacitance

values.

7.4.2 Noise

Most comparators have rather low gain. This allows the output to alternate between high and low when the input

signal changes slowly. The result is the output may oscillate between high and low when the differential input is

near zero and triggers on noise. The high gain of this comparator eliminates this problem. Less than 1

μV of

change on the input will drive the output from one rail to the other rail. If the input signal is noisy, the output

cannot ignore the noise unless some hysteresis is provided by positive feedback. (See Hysteresis.)

7.4.3 Hysteresis

It is a standard procedure to use hysteresis (positive feedback) around a comparator to prevent oscillation due to

the comparator triggering its own noise on slowly ramping signals. The following sections will describe various

ways to apply hysteresis.

7.4.3.1 Non-inverting Comparator With Hysteresis

(1)

(2)

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