Application Hints

1.0 Input Common-Mode Voltage Range

At supply voltages of 2.7V, 5V and 15V, the LMC6762 has an

input common-mode voltage range which exceeds both sup-

plies. As in the case of operational amplifiers, CMVR is de-

fined by the V

OS

shift of the comparator over the

common-mode range of the device. A CMRR (

∆V

common-mode range of the device. The absolute maximum

input voltage at V

at room temperature.

A wide input voltage range means that the comparator can

be used to sense signals close to ground and also to the

power supplies. This is an extremely useful feature in power

supply monitoring circuits.

An input common-mode voltage range that exceeds the sup-

plies, 20 fA input currents (typical), and a high input imped-

ance makes the LMC6762 ideal for sensor applications. The

LMC6762 can directly interface to sensors without the use of

amplifiers or bias circuits. In circuits with sensors which pro-

duce outputs in the tens to hundreds of millivolts, the

LMC6762 can compare the sensor signal with an appropri-

ately small reference voltage. This reference voltage can be

close to ground or the positive supply rail.

2.0 Low Voltage Operation

Comparators are the common devices by which analog sig-

nals interface with digital circuits. The LMC6762 has been

designed to operate at supply voltages of 2.7V without sac-

rificing performance to meet the demands of 3V digital sys-

tems.

At supply voltages of 2.7V, the common-mode voltage range

extends 200 mV (guaranteed) below the negative supply.

This feature, in addition to the comparator being able to

sense signals near the positive rail, is extremely useful in low

voltage applications.

4 µs with overdrives of 100 mV. Please refer to the perfor-

mance curves for more extensive characterization.

3.0 Shoot-Through Current

The shoot-through current is defined as the current surge,

above the quiescent supply current, between the positive

and negative supplies of a device. The current surge occurs

when the output of the device switches states. This transient

switching current results in glitches in the supply voltage.

Usually, glitches in the supply lines are compensated by by-

pass capacitors. When the switching currents are minimal,

the values of the bypass capacitors can be reduced

considerably.

DS012320-5

FIGURE 1. An Input Signal Exceeds the LMC6762

Power Supply Voltages with No Output Phase

Inversion

DS012320-6

FIGURE 2. Even at Low-Supply Voltage of 2.7V, an

Input Signal which Exceeds the Supply Voltages

Produces No Phase Inversion at the Output

DS012320-7

FIGURE 3. LMC6762 Circuit for Measurement

of the Shoot-Through Current

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