LMC6772

SNOS749F – SEPTEMBER 1995 – REVISED MARCH 2013

www.ti.com

APPLICATION INFORMATION

INPUT COMMON-MODE VOLTAGE RANGE

At supply voltages of 2.7V, 5V and 15V, the LMC6772 has an input common-mode voltage range which exceeds

both supplies. As in the case of operational amplifiers, CMVR is defined by the VOS shift of the comparator over

the common-mode range of the device. A CMRR (

ΔVOS/ΔVCM) of 75 dB (typical) implies a shift of < 1 mV over

the entire common-mode range of the device. The absolute maximum input voltage at V+ = 5V is 200 mV beyond

either supply rail at room temperature.

Figure 29. An Input Signal Exceeds the LMC6772 Power Supply Voltages with No Output Phase

Inversion

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 supplies, 20 fA input currents (typical), and a high input

impedance makes the LMC6772 ideal for sensor applications. The LMC6772 can directly interface to sensors

without the use of amplifiers or bias circuits. In circuits with sensors which produce outputs in the tens to

hundreds of millivolts, the LMC6772 can compare the sensor signal with an appropriately small reference

voltage. This reference voltage can be close to ground or the positive supply rail.

LOW VOLTAGE OPERATION

Comparators are the common devices by which analog signals interface with digital circuits. The LMC6772 has

been designed to operate at supply voltages of 2.7V, without sacrificing performance, to meet the demands of 3V

digital systems.

At supply voltages of 2.7V, the common-mode voltage range extends 200 mV (ensured) 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.

Figure 30. Even at Low-Supply Voltage of 2.7V, an Input Signal which Exceeds the Supply Voltages

Produces No Phase Inversion at the Output

At V+ = 2.7V, propagation delays are tPLH = 4 μs and tPHL = 4 μs with overdrives of 100 mV. Please refer to the

performance curves for more extensive characterization.

12

Submit Documentation Feedback

Copyright © 1995–2013, Texas Instruments Incorporated

Product Folder Links: LMC6772