LM4952TS datasheet(16/20 Pages) NSC

16 / 20 page

Application Information (Continued)

manner, the ground lead of the capacitor connected between

the BYPASS pin and GND should also be connected to the

package’s grounded tab.

OPTIMIZING CLICK AND POP REDUCTION

PERFORMANCE

The LM4952 contains circuitry that eliminates turn-on and

shutdown transients ("clicks and pops"). For this discussion,

turn-on refers to either applying the power supply voltage or

when the micro-power shutdown mode is deactivated.

As the V

DD/4 voltage present at the BYPASS pin ramps to its

final value, the LM4952’s internal amplifiers are muted. Once

the voltage at the BYPASS pin reaches V

DD/4, the amplifiers

are unmuted.

The gain of the internal amplifiers remains unity until the

voltage on the bypass pin reaches V

DD/4. As soon as the

voltage on the bypass pin is stable, the device becomes fully

operational and the amplifier outputs are reconnected to

their respective output pins.

In order eliminate "clicks and pops", all capacitors must be

discharged before turn-on. Rapidly switching V

DD may not

allow the capacitors to fully discharge, which may cause

"clicks and pops".

There is a relationship between the value of C

and

BYPASS that ensures minimum output transient when power

is applied or the shutdown mode is deactivated. Best perfor-

mance is achieved by selecting a C

BYPASS value that is

greater than twelve times C

IN’s value.

RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT

Figure 9 through Figure 11 show the recommended two-

layer PC board layout that is optimized for the TO263-

packaged, SE-configured LM4952 and associated external

components. These circuits are designed for use with an

external 12V supply and 4

Ω(min)(SE) speakers.

These circuit boards are easy to use. Apply 12V and ground

to the board’s V

DD and GND pads, respectively. Connect a

speaker between the board’s OUT

A and OUTB outputs and

respective GND pins.

LM4952TS Datasheet(PDF) 16 Page - National Semiconductor (TI)

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