LM4892 NSC [National Semiconductor], LM4892 Datasheet - Page 13

• Manufacturer Part Number: LM4892
• Description: 1 Watt Audio Power Amplifier with Headphone Sense
• Manufacturer: NSC [National Semiconductor]

Application Information
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
needed as shown in Figure 3 to bandwidth limit the amplifier.
This feedback capacitor creates a low pass filter that elimi-
(Continued)
FIGURE 3. Higher Gain Audio Amplifier
f
) may be
13
nates possible high frequency oscillations. Care should be
taken when calculating the -3dB frequency in that an incor-
rect combination of R
A typical combination of feedback resistor and capacitor that
will not produce audio band high frequency rolloff is R
20kΩ and C
point of approximately 320 kHz.
f
= 25pF. These components result in a -3dB
f
and C
f
will cause rolloff before 20kHz.
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f
=