Datasheet

LM49350, LM49350RLEVAL
SNAS359D –SEPTEMBER 2008–REVISED JUNE 2012 www.ti.com
PCB LAYOUT CONSIDERATIONS
Microphone Inputs
When routing the differential microphone inputs the electrical length of the two traces should be well matched.
The differential input pair can be routed in parallel on the same plane or the traces can overlap on two adjacent
planes. It is important to surround these traces with a ground plane or trace to isolate the microphone inputs from
the noise coupling from the class D amplifier.
Class D Loudspeaker
To minimize trace resistance and therefore maintain the highest possible output power, the power (LS_V
DD
) and
class D output (LS-, LS+) traces should be as wide as possible. It is also essential to keep these same traces as
short and well shielded as possible to decrease the amount of EMI radiation.
Capacitors
All supply bypass capacitors (for A_V
DD
, D_V
DD
. I/O V
DD
, and LS_V
DD
), and charge pump capacitors should be
as close to the device as possible. Careful consideration should be taken with the ground connection of the
analog supply (A_V
DD
) bypass cap, for proper performance it should be referenced to a low noise ground plane.
The charge pump capacitors and traces connecting the capacitor to the device should be kept away from the
input and output traces to avoid noise coupling issues.
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