LM7321, LM7322

SNOSAW8E – MAY 2008 – REVISED SEPTEMBER 2015

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Device Functional Modes (continued)

NOTE

Because of the lower output sourcing current compared to the sinking one, the Slew Rate

limit under heavy capacitive loading is determined by the positive transitions.

An estimate of positive and negative slew rates for loads larger than 100 nF can be made by dividing the short

circuit current value by the capacitor.

For the LM732xx, the available output current increases with the input overdrive. Referring to Figure 64 and

Figure 65, it can be seen that both sourcing and sinking short circuit current increase as input overdrive

increases. In a closed-loop amplifier configuration, during transient conditions while the fed back output has not

quite caught up with the input, there will be an overdrive imposed on the input allowing more output current than

would normally be available under steady-state condition. Because of this feature, the output stage quiescent

current of the op amp can be kept to a minimum, thereby reducing power consumption, while enabling the device

to deliver large output current when the need arises (such as during transients).

Figure 64. Output Short Circuit Sourcing Current vs. Input

Figure 65. Output Short Circuit Sinking Current vs. Input

Overdrive

Overdrive

transition, the input overdrive reaches 1-V peak and is more than enough to cause the output current to increase

to its maximum value (see Figure 64 and Figure 65 plots).

NOTE

Because of the larger output sinking current compared to the sourcing one, the output

negative transition is faster than the positive one.

Figure 66. Buffer Amplifier Scope Photo

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