LMV7271, LMV7272, LMV7275

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SNOSA56I – FEBRUARY 2003 – REVISED SEPTEMBER 2015

Feature Description (continued)

7.3.2 Output Stage, LMV7271 and LMV7272

Figure 25. LMV7271 and LMV7272 Push-Pull Output Stage

The LMV7271 and LMV7272 have a push-pull output stage. This output stage keeps the total system power

consumption to the absolute minimum by eliminating the need for a pullup resistor. The only current consumed is

the low supply current and the current going directly into the load.

When the output switches, both PMOS and NMOS at the output stage are on at the same time for a very short

time. This allows current to flow directly between V+ and V− through output transistors. The result is a short spike

of current (called shoot-through current) drawn from the supply and glitches in the supply voltages. The glitches

can spread to other parts of the board as noise. To prevent the glitches in supply lines, power supply bypass

capacitors must be installed. See Circuit Techniques for Avoiding Oscillations in Comparator Applications for

supply bypassing for details.

7.3.3 Output Stage, LMV7275

Figure 26. LMV7275 Open-Drain Output

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

to operate properly. The internal circuitry is identical to the LMV7271 except that the upper P-channel output

device is absent. When the internal output transistor is off, the output voltage will be pulled up to the external

positive voltage by the external pullup resistor. This allows the output to be OR'ed with other open-drain outputs

on the same bus. The output pullup 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 is not affected by capacitive loads at the output of the LMV7271 or LMV7272. However,

resistive loads slightly effect the propagation delay on the falling edge depending on the load resistance value.

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

values.

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