ADAU1381BCPZ Analog Devices Inc, ADAU1381BCPZ Datasheet - Page 42

IC AUDIO CODEC STEREO LN 32LFCSP

ADAU1381BCPZ

Manufacturer Part Number
ADAU1381BCPZ
Description
IC AUDIO CODEC STEREO LN 32LFCSP
Manufacturer
Analog Devices Inc
Type
Stereo Audior
Datasheet

Specifications of ADAU1381BCPZ

Data Interface
Serial, SPI™
Resolution (bits)
24 b
Number Of Adcs / Dacs
2 / 2
Sigma Delta
No
S/n Ratio, Adcs / Dacs (db) Typ
97 / 100
Dynamic Range, Adcs / Dacs (db) Typ
96.5 / 100
Voltage - Supply, Analog
1.8 V ~ 3.65 V
Voltage - Supply, Digital
1.63 V ~ 3.65 V
Operating Temperature
-25°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
32-VFQFN, CSP Exposed Pad
Audio Codec Type
Stereo
No. Of Adcs
2
No. Of Dacs
2
No. Of Input Channels
3
No. Of Output Channels
3
Adc / Dac Resolution
24bit
Adcs / Dacs Signal To Noise Ratio
100dB
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
ADAU1381
APPLICATIONS INFORMATION
POWER SUPPLY BYPASS CAPACITORS
Each analog and digital power supply pin should be bypassed to
its nearest appropriate ground pin with a single 100 nF capacitor.
The connections to each side of the capacitor should be as short
as possible, and the trace should stay on a single layer with no
vias. For maximum effectiveness, locate the capacitor equidistant
from the power and ground pins or, when equidistant placement
is not possible, slightly closer to the power pin. Thermal connec-
tions to the ground planes should be made on the far side of the
capacitor.
Each supply signal on the board should also be bypassed with a
single bulk capacitor (10 μF to 47 μF).
GSM NOISE FILTER
In mobile applications, excessive 217 Hz GSM noise on the
analog supply pins can degrade the quality of the audio signal.
To avoid this problem, it is recommended that an LC filter be
used in series with the bypass capacitors for the AVDD pins.
This filter should consist of a 1.2 nH inductor and a 9.1 pF
capacitor in series between AVDDx and ground, as shown in
Figure 54.
Figure 53. Recommended Power Supply Bypass Capacitor Layout
Figure 54. GSM Filter on the Analog Supply Pins
AVDD1
CAPACITOR
TO VDD
AVDD2
1.2nH
VDD
0.1µF
0.1µF
10µF
+
TO GND
9.1pF
GND
Rev. B | Page 42 of 84
GROUNDING
A single ground plane should be used in the application layout.
Components in an analog signal path should be placed away
from digital signals.
SPEAKER DRIVER SUPPLY TRACE (AVDD2)
The trace supplying power to the AVDD2 pin has higher current
requirements than the AVDD1 pin (up to 300 mA). An appro-
priately thick trace is recommended.
EXPOSED PAD PCB DESIGN
The ADAU1381 LFCSP package has an exposed pad on the
underside. This pad is used to couple the package to the PCB
for heat dissipation when using the outputs to drive earpiece or
headphone loads. When designing a board for the ADAU1381,
special consideration should be given to the following:
A copper layer equal in size to the exposed pad should be
on all layers of the board, from top to bottom, and should
connect somewhere to a dedicated copper board layer (see
Figure 55).
Vias should be placed to connect all layers of copper,
allowing for efficient heat and energy conductivity. For an
example, see Figure 56, which has nine vias arranged in a
3 inch × 3 inch grid in the pad area.
Figure 55. Exposed Pad Layout Example, Side View
Figure 56. Exposed Pad Layout Example, Top View
VIAS
COPPER SQUARES
TOP
GROUND
POWER
BOTTOM

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