Typical Application Circuit
Supply Bypassing, Layout, and Grounding
Proper layout and grounding are essential for optimum
performance. Use wide traces for the power-supply
inputs and amplifier outputs to minimize losses due to
parasitic trace resistance. Proper grounding improves
audio performance, minimizes crosstalk between chan-
nels, and prevents switching noise from coupling into
the audio signal. Connect PGND and AGND together at
a single point on the PCB. Route all traces that carry
switching transients away from AGND and the
traces/components in the audio signal path.
Bypass PVDD with two 1µF capacitors to PGND. Place
the bypass capacitors as close as possible to the
MAX9737. Place a 100µF capacitor between PVDD and
PGND. Bypass V
S
,V
COM
, and V
REG
with a 1µF capacitor
to AGND.
Use wide, low-resistance output traces. Current drawn
from the outputs increases as load impedance
decreases. High-output trace resistance decreases the
power delivered to the load. The MAX9737 TQFN pack-
age features an exposed thermal pad on its underside.
This pad lowers the package’s thermal resistance by
providing a heat conduction path from the die to the
PCB. Connect the exposed thermal pad to PGND by
using a large pad and multiple vias to the PGND plane.
