LM2524D, LM3524D

SNVS766E – JUNE 2009 – REVISED MAY 2013

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Figure 13.

Error Amplifier

The error amplifier is a differential input, transconductance amplifier. Its gain, nominally 86 dB, is set by either

feedback or output loading. This output loading can be done with either purely resistive or a combination of

resistive and reactive components. A graph of the amplifier's gain vs output load resistance is shown in

Figure 14.

Figure 14.

The output of the amplifier, or input to the pulse width modulator, can be overridden easily as its output

error amplifier and force a particular duty cycle to the outputs. An example of this could be a non-regulating

motor speed control where a variable voltage was applied to pin 9 to control motor speed. A graph of the output

duty cycle vs the voltage on pin 9 is shown in Figure 15.

The duty cycle is calculated as the percentage ratio of each output's ON-time to the oscillator period. Paralleling

the outputs doubles the observed duty cycle.

10

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