Rainbow Electronics MAX9860 - Manual (Page 36)

Applications Information
Proper layout and grounding are essential for optimum
performance. When designing a PCB for the MAX9860,
partition the circuitry so that the analog sections of the
MAX9860 are separated from the digital sections. This
ensures that the analog audio traces do not need to be
routed near digital traces.
Use a large continuous ground plane on a dedicated
layer of the PCB to minimize loop areas. Connect
AGND, DGND, and MICGND directly to the ground
plane using the shortest trace length possible. Proper
grounding improves audio performance, minimizes
crosstalk between channels, and prevents any digital
noise from coupling into the analog audio signal.
Ground the bypass capacitors on REG, PREG, and REF
directly to the ground plane with minimum trace length.
Also be sure to minimize the path length to AGND and
MICGND. Bypass AVDD directly to AGND. Bypass
MICBIAS directly to MICGND.
Connect all digital I/O termination to the ground plane
with minimum path length to DGND. Bypass DVDD and
DVDDIO directly to DGND.
Route microphone signals from the microphone to the
MAX9860 as a differential pair, ensuring that the positive
and negative signals follow the same path as closely as
possible with equal trace length. When using single-
ended microphones or other single-ended audio
sources, AC ground the negative microphone input sig-
nal as near to the audio source as possible and then treat
the positive and negative traces as differential pairs.
The MAX9860 thin QFN package features an exposed
thermal pad on its underside. This pad lowers the pack-
age’s thermal resistance by providing a direct heat
conduction path from the die to the PCB. Connect the
exposed thermal pad to AGND.
An evaluation kit (EV kit) is available to provide an
example layout for the MAX9860. The EV kit allows
quick setup of the MAX9860 and includes easy-to-use
software allowing all internal registers to be controlled.
MAX9860
16-Bit Mono Audio Voice Codec
36 ______________________________________________________________________________________
23 24 22 21
8 7 9
REG
REF
AGND
AVDD
10
MICBIAS
LRCLK
SDOUT
MCLK
BCLK
DVDD
1
2
MICLN
4
5
6
17
18
16
14
13
MICLP MICGND
SCL SDA
OUTN OUTP
MAX9860
PREG SDIN 3
15
MICRP
20
11
DVDDIO
MICRN
19
12
DGND
IRQ
THIN QFN
4mm x 4mm
TOP VIEW
*EP
*EP = EXPOSED PAD
+
Pin Configuration