LM4854 datasheet(24/29 Pages) NSC

24 / 29 page

Application Information (Continued)

The product of the desired high frequency cutoff (100kHz in

this example) and the differential gain AVD, determines the

upper passband response limit. With AVD = 3 and fH =

100kHz, the closed-loop gain bandwidth product (GBWP) is

300kHz. This is less than the LM4854’s 3.5MHz GBWP. With

this margin, the amplifier can be used in designs that require

more differential gain while avoiding performance restricting

bandwidth limitations.

RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT

Figures 5 through 9 show the recommended four-layer PC

board layout that is optimized for the micro SMD-packaged

LM4854 and associated external components. Figures 10

through 12 show the recommended two-layer PC board

layout that is optimized for the TSSOP-packaged LM4854

and associated external components. Figures 13 through 17

show the recommended four-layer PC board layout that is

optimized for the LLP-packaged LM4854 and associate ex-

ternal components.

These circuits are designed for use with an external 5V

supply and 8

Ω(min) speakers.These circuit boards are easy

to use. Apply 5V and ground to the board’s V

DD and GND

pads, respectively. Connect a speaker between the board’s

L-OUT and BTL-OUT or headphones to the headphone jack

(L-OUT and R-OUT outputs).

Demonstration Board Layout

20038221

FIGURE 5. Recommended microSMD PC Board

Layout:

Component-Side SilkScreen

20038222

FIGURE 6. Recommended microSMD PC Board

Layout:

Component-Side Layout

20038223

FIGURE 7. Recommended microSMD PC Board

Layout:

Upper Inner-Layer Layout

20038224

FIGURE 8. Recommended microSMD PC Board

Layout:

Lower Inner-Layout Layer

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