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-IN

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OUT

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V

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LM7321, LM7322

SNOSAW8E – MAY 2008 – REVISED SEPTEMBER 2015

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8 Detailed Description

8.1 Overview

The LM732xx devices are rail-to-rail input and output amplifiers with wide operating voltages and high-output

currents. The LM732xx family is efficient, achieving 18-V/µs slew rate and 20-MHz unity gain bandwidth while

requiring only 1 mA of supply current per op amp. The LM732xx device performance is fully specified for

operation at 2.7 V, ±5 V and ±15 V.

The LM732xx devices are designed to drive unlimited capacitive loads without oscillations. All LM7321x and

LM7322x parts are tested at

−40°C, 125°C, and 25°C, with modern automatic test equipment. High performance

from

−40°C to 125°C, detailed specifications, and extensive testing makes them suitable for industrial,

automotive, and communications applications.

Greater than rail-to-rail input common-mode voltage range with 50 dB of common-mode rejection across this

wide voltage range, allows both high-side and low-side sensing. Most device parameters are insensitive to power

supply voltage, and this makes the parts easier to use where supply voltage may vary, such as automotive

electrical systems and battery-powered equipment. These amplifiers have true rail-to-rail output and can supply a

respectable amount of current (15 mA) with minimal head room from either rail (300 mV) at low distortion (0.05%

THD+Noise).

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Output Short Circuit Current and Dissipation Issues

The LM732xx output stage is designed for maximum output current capability. Even though momentary output

shorts to ground and either supply can be tolerated at all operating voltages, longer lasting short conditions can

cause the junction temperature to rise beyond the absolute maximum rating of the device, especially at higher

supply voltage conditions. Below supply voltage of 6 V, the output short circuit condition can be tolerated

indefinitely.

With the op amp tied to a load, the device power dissipation consists of the quiescent power due to the supply

current flow into the device, in addition to power dissipation due to the load current. The load portion of the

power itself could include an average value (due to a DC load current) and an AC component. DC load current

would flow if there is an output voltage offset, or the output AC average current is non-zero, or if the op amp

operates in a single supply application where the output is maintained somewhere in the range of linear

operation.

Therefore,

(1)

20

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