LM4877 National Semiconductor, LM4877 Datasheet - Page 10

• Manufacturer Part Number: LM4877
• Description: 1 Watt Audio Power Amplifier in micro SMD package with Shutdown Logic Low
• Manufacturer: National Semiconductor

www.national.com
Application Information
HIGHER GAIN AUDIO AMPLIFIER
The LM4877 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 may be needed as
shown in Figure 2 to bandwidth limit the amplifier. This feed-
back capacitor creates a low pass filter that eliminates
(Continued)
Figure 2
10
possible high frequency oscillations. Care should be taken
when calculating the -3dB frequency in that an incorrect
combination of R
typical combination of feedback resistor and capacitor that
will not produce audio band high frequency rolloff is R
20k
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.
and C
4
= 25pf. These components result in a -3dB
3
and C
4
will cause rolloff before 20kHz. A
DS101290-24
3
=