LM4818 datasheet(12/16 Pages) NSC

tên linh kiện	LM4818

Giải thích chi tiết về linh kiện	350mW Audio Power Amplifier with Shutdown Mode

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Application Information (Continued)

HIGHER GAIN AUDIO AMPLIFIER

The LM4818 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 2 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

and C

will cause rolloff before

20kHz. A typical combination of feedback resistor and ca-

pacitor that will not produce audio band high frequency rolloff

is R

3 = 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 imple-

ment a band limiting filter below 100kHz.

DS200389-75

Figure 2

LM4818 bảng dữ liệu(PDF) 12 Page - National Semiconductor (TI)