LM4892 datasheet(13/22 Pages) NSC

部品番号	LM4892

部品情報	1 Watt Audio Power Amplifier with Headphone Sense

PDF	22 Pages

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メーカー	NSC [National Semiconductor (TI)]

ホームページ	http://www.national.com

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13 / 22 page

Application Information (Continued)

The LM4892 is unity-gain stable and requires no external

components besides gain-setting resistors, an input coupling

capacitor, and proper supply bypassing in the typical appli-

cation. However, if a closed-loop differential gain of greater

than 10 is required, a feedback capacitor (C

may be

needed as shown in Figure 3 to bandwidth limit the amplifier.

This feedback capacitor creates a low pass filter that elimi-

nates possible high frequency oscillations. Care should be

taken when calculating the -3dB frequency in that an incor-

rect combination of R

f and Cf will cause rolloff before 20kHz.

A typical combination of feedback resistor and capacitor that

will not produce audio band high frequency rolloff is R

f =

20k

Ω and C

f = 25pF. These components result in a -3dB

point of approximately 320 kHz.

20012724

FIGURE 3. Higher Gain Audio Amplifier

LM4892 データシート(PDF) 13 Page - National Semiconductor (TI)