Rainbow Electronics MAX9867 - Manual (Page 49)

MAX9867
Ultra-Low Power Stereo Audio Codec
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ACKNOWLEDGE FROM MAX9867
1 BYTE
AUTOINCREMENT INTERNAL
REGISTER ADDRESS POINTER
ACKNOWLEDGE FROM MAX9867
A A A P 0
ACKNOWLEDGE FROM MAX9867
R/W
S
R/W REPEATED START
Sr 1 SLAVE ADDRESS REGISTER ADDRESS SLAVE ADDRESS DATA BYTE
Figure 15. Reading n Bytes of Data from the MAX9867
Applications Information
Proper layout and grounding are essential for optimum
performance. When designing a PCB for the MAX9867,
partition the circuitry so that the analog sections of the
MAX9867 are separated from the digital sections. This
ensures that the analog audio traces are not routed
near digital traces.
Use a large continuous ground plane on a dedicated
layer of the PCB to minimize loop areas. Connect
AGND and DGND 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 signals.
Ground the bypass capacitors on MICBIAS, REG,
PREG, and REF directly to the ground plane with mini-
mum trace length. Also be sure to minimize the path
length to AGND. Bypass AVDD directly to AGND.
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
MAX9867 as a differential pair, ensuring that the posi-
tive and negative signals follow the same path as close-
ly as possible with equal trace length. When using
single-ended microphones or other single-ended audio
sources, ground the negative microphone input as near
as possible to the audio source and then treat the posi-
tive and negative traces as differential pairs.
The MAX9867 TQFN package features an exposed
thermal pad on its underside. Connect the exposed
thermal pad to AGND.
An evaluation kit (EV Kit) is available to provide an
example layout for the MAX9867. The EV kit allows
quick setup of the MAX9867 and includes easy-to-use
software, allowing all internal registers to be controlled.