LM7341

SNOSAW9B – MAY 2008 – REVISED MARCH 2013

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APPLICATION INFORMATION

GENERAL INFORMATION

Low supply current and wide bandwidth, greater than rail-to-rail input range, full rail-to-rail output, good capacitive

load driving ability, wide supply voltage and low distortion all make the LM7341 ideal for many diverse

applications.

The high common-mode rejection ratio and full rail-to-rail input range provides precision performance when

operated in non-inverting applications where the common-mode error is added directly to the other system

errors.

CAPACITIVE LOAD DRIVING

The LM7341 has the ability to drive large capacitive loads. For example, 1000 pF only reduces the phase margin

to about 30 degrees.

POWER DISSIPATION

Although the LM7341 has internal output current limiting, shorting the output to ground when operating on a

+30V power supply will cause the op amp to dissipate about 350 mW. This is a worst-case example. In the 5-pin

SOT-23 package, the higher thermal resistance will cause a calculated rise of 113°C. This can raise the junction

temperature to above the absolute maximum temperature of 150°C.

Operating from split supplies greatly reduces the power dissipated when the output is shorted. Operating on

±15V supplies can only cause a temperature rise of 57°C in the 5-pin SOT-23 package, assuming the short is to

ground.

WIDE SUPPLY RANGE

The high power-supply rejection ratio (PSRR) and common mode rejection ratio (CMRR) provide precision

performance when operated on battery or other unregulated supplies. This advantage is further enhanced by the

very wide supply range (2.5V–32V) offered by the LM7341. In situations where highly variable or unregulated

supplies are present, the excellent PSRR and wide supply range of the LM7341 benefit the system designer with

continued precision performance, even in such adverse supply conditions.

SPECIFIC ADVANTAGES OF 5-Pin SOT-23 (TinyPak)

The obvious advantage of the 5-pin SOT-23, TinyPak, is that it can save board space, a critical aspect of any

portable or miniaturized system design. The need to decrease overall system size is inherent in any handheld,

portable, or lightweight system application.

Furthermore, the low profile can help in height limited designs, such as consumer hand-held remote controls,

sub-notebook computers, and PCMCIA cards.

An additional advantage of the tiny package is that it allows better system performance due to ease of package

placement. Because the tiny package is so small, it can fit on the board right where the op amp needs to be

placed for optimal performance, unconstrained by the usual space limitations. This optimal placement of the tiny

package allows for many system enhancements, not easily achieved with the constraints of a larger package.

For example, problems such as system noise due to undesired pickup of digital signals can be easily reduced or

mitigated. This pick-up problem is often caused by long wires in the board layout going to or from an op amp. By

placing the tiny package closer to the signal source and allowing the LM7341 output to drive the long wire, the

signal becomes less sensitive to such pick-up. An overall reduction of system noise results.

Often times system designers try to save space by using dual or quad op amps in their board layouts. This

causes a complicated board layout due to the requirement of routing several signals to and from the same place

on the board. Using the tiny op amp eliminates this problem.

Additional space savings parts are available in tiny packages from Texas Instruments, including low power

amplifiers, precision voltage references, and voltage regulators.

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