LM4752 datasheet(15/22 Pages) NSC

15 / 22 page

Application Information (Continued)

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

terminated at all times. If the inputs are left floating, the

amplifier will have a positive feedback path through high

impedance 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

Ω or less on the AC side of

the input coupling capacitors.

UNDERVOLTAGE SHUTDOWN

If the power supply voltage drops below the minimum oper-

ating supply voltage, the internal under-voltage detection

circuitry pulls down the half-supply bias line, shutting down

the preamp section of the LM4752. Due to the wide operat-

ing supply range of the LM4752, the threshold is set to just

under 9V. There may be certain applications where a higher

10003930

FIGURE 5. Bridge-Mode Application

10003931

10003937

FIGURE 6. THD+N vs. P

OUT for Bridge-Mode Application

LM4752 Datasheet(PDF) 15 Page - National Semiconductor (TI)