LMV791, LMV792

SNOSAG6G – SEPTEMBER 2005 – REVISED OCTOBER 2015

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7 Detailed Description

7.1 Overview

The LMV79x family provides optimal performance in low-voltage and low-noise systems. A low-noise CMOS

input stage, with typical input bias currents in the range of a few femtoamperes, and an input common-mode

voltage range which includes ground make the LMV791 and the LMV792 ideal for low-power sensor applications

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Wide Bandwidth at Low Supply Current

The LMV791 and LMV792 are high performance operational amplifiers that provide a unity gain bandwidth of 17

MHz while drawing a low supply current of 1.15 mA. This makes them ideal for providing wideband amplification

in portable applications. The shutdown feature can also be used to design more power efficient systems that

offer wide bandwidth and high performance while consuming less average power.

7.3.2 Low Input Referred Noise and Low Input Bias Current

The LMV79x have a very low input referred voltage noise density (5.8 nV/

√Hz at 1 kHz). A CMOS input stage

ensures a small input bias current (100 fA) and low input referred current noise (0.01 pA/

√Hz). This is very

helpful in maintaining signal fidelity, and makes the LMV791 and LMV792 ideal for audio and sensor-based

applications.

7.3.3 Low Supply Voltage

The LMV791 and the LMV792 have performance ensured at 2.5-V and 5-V supply. The LMV791 family is

ensured to be operational at all supply voltages between 2 V and 5.5 V, for ambient temperatures ranging from

−40°C to 125°C, thus using the entire battery lifetime. The LMV791 and LMV792 are also ensured to be

operational at 1.8-V supply voltage, for temperatures between 0°C and 125°C. This makes the LMV791 family

ideal for usage in low-voltage commercial applications.

7.3.4 Rail-to-Rail Output and Ground Sensing

Rail-to-rail output swing provides maximum possible dynamic range at the output. This is particularly important

when operating at low supply voltages. An innovative positive feedback scheme is used to boost the current drive

capability of the output stage. This allows the LMV791 and the LMV792 to source more than 40 mA of current at

1.8-V supply. This also limits the performance of the LMV791 family as comparators, and hence the usage of the

LMV791 and the LMV792 in an open-loop configuration is not recommended. The input common-mode range

includes the negative supply rail which allows direct sensing at ground in single supply operation.

7.3.5 Shutdown Feature

The LMV791 family is ideal for battery-powered systems. With a low supply current of 1.15 mA and a shutdown

current of 140 nA typically, the LMV791 and LMV792 allow the designer to maximize battery life. The enable pin

of the LMV791 and the LMV792 allows the operational amplifier to be turned off and reduce its supply current to

less than 1

16

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