SM72375_14 Datasheet, PDF (9/20 Pages) Texas Instruments – SM72375 SolarMagic Dual Micropower Rail-To-Rail Input CMOS Comparator with Open Drain Output

SM72375
www.ti.com
SNIS155D – NOVEMBER 2010 – REVISED APRIL 2013
APPLICATION INFORMATION
1.0 INPUT COMMON-MODE VOLTAGE RANGE
At supply voltages of 2.7V, 5V and 15V, the SM72375 has an input common-mode voltage range (CMVR) which
exceeds both supplies. As in the case of operational amplifiers, CMVR is defined by the V_OS shift of the
comparator over the common-mode range of the device. A common-mode rejection ratio (CMRR, defined as
ΔV_OS/ΔV_CM) 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 23. An Input Signal Exceeds the SM72375 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 SM72375 ideal for sensor applications. The SM72375 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 SM72375 can compare the sensor signal with an appropriately 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 signals interface with digital circuits. The SM72375 is
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 24. 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 t_PLH = 4 μs and t_PHL = 4 μs with overdrives of 100 mV. Please refer to the
Typical Performance Characteristics section for more extensive characterization.
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