LMV7271: output glitch during IN+ and V+ rising

Hello Allen,

This is actually fairly common. The output of a comaprator can randomly "flop" around when the supply voltage is below the specified minimum supply voltage. The slow supply ramp makes it more apparent.

When below the minimum supply, the output may not be responding to the inputs since the internal biasing is not correct (yet). So even though the input conditions are correct, the comparator is not yet responding. This is usually most apparent when the supply voltage is below 1V, and rail-to-rail input devices are more suceptable. There is also a contribution of start-up time. Devices do not instantly start-up - there is usually a small amount of time required for the internal biasing to set-up. Since this is a micropwer device, the startup time can be a few milliseconds.

The LMV7271 has a minimum supply voltage of 1.8V, so it should "wake up" by about 1.5V. Below that, the output could randomly transition, depending on the internal leakages of the individual device. All devices may not act the same.

For these exact reasons, we have developed new comparators that have an internal power-on reset, where a minimum supply voltage and time must be met before the output starts responding to the inputs. During the "wake-up" period, the output is held in a known condition.

Comparators with the power-on reset function are the newer TLV7011 and TLV7031 family, and the TLV1805.

Unfortunately, these devices do not have the same pinout as the LMV7271 - so a re-layout would be needed to use these devices. We do not have any POR capable devices in the LMV7271 pinout.