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LMV331TP / LMV393TP

General Purpose, 1.8V, RRI, Open-Drain Output Comparators

www.3peakic.com.cn

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Low Input Bias Current

The LMV331-393 are CMOS comparator family and feature very low input bias current in pA range. The low input

bias current allows the comparators to be used in applications with high resistance sources. Care must be taken

to minimize PCB Surface Leakage. See below section on “PCB Surface Leakage” for more details.

PCB Surface Leakage

In applications where low input bias current is critical, Printed Circuit Board (PCB) surface leakage effects need to

be considered. Surface leakage is caused by humidity, dust or other contamination on the board. Under low

current to flow, which is greater than the LMV331-393’s input bias current at +27°C (±6pA, typical). It is

recommended to use multi-layer PCB layout and route the comparator’s -IN and +IN signal under the PCB

surface.

The effective way to reduce surface leakage is to use a guard ring around sensitive pins (or traces). The guard

ring is biased at the same voltage as the sensitive pin. An example of this type of layout is shown in Figure 6 for

Inverting configuration application.

1. For Non-Inverting Configuration:

comparator.

2. For Inverting Configuration:

Figure 6. Example Guard Ring Layout for Inverting Comparator

Ground Sensing and Rail to Rail Output

The LMV331-393 implement a rail-to-rail topology that is capable of swinging to within 10mV of either rail. Since

the inputs can go 300mV beyond either rail, the comparator can easily perform ‘true ground’ sensing.

The maximum output current is a function of total supply voltage. As the supply voltage of the comparator

increases, the output current capability also increases. Attention must be paid to keep the junction temperature of

the IC below 150°C when the output is in continuous short-circuit condition. The output of the amplifier has

reverse-biased ESD diodes connected to each supply. The output should not be forced more than 0.5V beyond

either supply, otherwise current will flow through these diodes.

ESD

The LMV331-393 have reverse-biased ESD protection diodes on all inputs and output. Input and output pins can

not be biased more than 300mV beyond either supply rail.