LM4819MM datasheet(14/27 Pages) TI

14 / 27 page

LM4819, LM4819MBD

SNAS133D – FEBRUARY 2001 – REVISED MARCH 2013

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Figure 26. Higher Gain Audio Amplifier

The LM4819 is unity-gain stable and requires no external components besides gain-setting resistors, an input

coupling capacitor, and proper supply bypassing in the typical application. However, if a closed-loop differential

gain of greater than 10 is required, a feedback capacitor (C4) may be needed as shown in Figure 26 to

bandwidth limit the amplifier. This feedback capacitor creates a low pass filter that eliminates possible high

frequency oscillations. Care should be taken when calculating the -3dB frequency in that an incorrect

combination of R3 and C4 will cause rolloff before 20kHz. A typical combination of feedback resistor and

capacitor that will not produce audio band high frequency rolloff is R3 = 20kΩ and C4 = 25pF. These components

result in a -3dB point of approximately 320 kHz. It is not recommended that the feedback resistor and capacitor

be used to implement a band limiting filter below 100kHz.

Figure 27. Differential Amplifier Configuration for LM4819

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LM4819MM Datasheet(PDF) 14 Page - Texas Instruments