LMV7255M7 datasheet(8/11 Pages) NSC

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Application Info (Continued)

Input Stage

The LMV7251 and LMV7255 have rail-to-rail input stages.

The input common mode voltage range is from −100mV to

CC + 100mV).

Output Stage

The LMV7251 has a push-pull CMOS output stage. Large

push-pull output drivers allows rail-to-rail output swings with

load currents in the miliampere range.

The LMV7255 has a open drain CMOS output stage. This

requires an external pull-up resistor connected between the

positive supply voltage and the output. The external pull-up

resistor should be high enough resistance so to avoid exces-

sive power dissipation. In addition, the pull-up resistor

should be low enough resistance to enable the comparator

to switch with the load circuitry connected.

Power Supply Considerations

The LMV7251/LMV7255 are well suited for many battery-

powered applications. The LMV7251/LMV7255 can operate

from single power supply of +1.8V to +5V. The device typi-

cally consumes only 11µA with a 2.7V supply. With a high

power supply rejection ratio (PSRR) of 79 dB (typical), the

comparator is well suited for operating under conditions of a

decaying battery voltage.

Power supply decoupling is critical and improves stability.

Place decoupling capacitors 0.1µF as close as possible to

the V

+ pin. For split supply applications, place decoupling

capacitors 0.1µF on both the V

+ and V− pins. The decoupling

capacitors will help keep the comparator from oscillating

under various load conditions.

DS200057-20

DS200057-21

FIGURE 4. Inverting Configured Comparator —

LMV7255

LMV7255M7 Datasheet(PDF) 8 Page - National Semiconductor (TI)