LM4752T National Semiconductor, LM4752T Datasheet - Page 11

• Manufacturer Part Number: LM4752T
• Description: Stereo 11W Audio Power Amplifier
• Manufacturer: National Semiconductor

Application Information
PREVENTING OSCILLATIONS
With the integration of the feedback and bias resistors on-
chip, the LM4752 fits into a very compact package. However,
due to the close proximity of the non-inverting input pins to
the corresponding output pins, the inputs should be AC ter-
minated at all times. If the inputs are left floating, the ampli-
fier will have a positive feedback path through high imped-
ance coupling, resulting in a high frequency oscillation. In
most applications, this termination is typically provided by
the previous stage’s source impedance. If the application will
require an external signal, the inputs should be terminated to
ground with a resistance of 50 k
the input coupling capacitors.
FIGURE 6. THD+N vs. P
or less on the AC side of
(Continued)
DS100039-31
FIGURE 5. Bridge-Mode Application
OUT
11
for Bridge-Mode Application
UNDERVOLTAGE SHUTDOWN
If the power supply voltage drops below the minimum oper-
ating supply voltage, the internal under-voltage detection cir-
cuitry pulls down the half-supply bias line, shutting down the
preamp section of the LM4752. Due to the wide operating
supply range of the LM4752, the threshold is set to just un-
der 9V. There may be certain applications where a higher
threshold voltage is desired. One example is a design requir-
ing a high operating supply voltage, with large supply and
bias capacitors, and there is little or no other circuitry con-
nected to the main power supply rail. In this circuit, when the
power is disconnected, the supply and bias capacitors will
discharge at a slower rate, possibly resulting in audible out-
put distortion as the decaying voltage begins to clip the out-
DS100039-30
DS100039-37
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