MAX9888 Maxim Integrated Products, MAX9888 Datasheet - Page 110

• Manufacturer Part Number: MAX9888
• Description: Stereo Audio CODEC
• Manufacturer: Maxim Integrated Products

DataSheet.in
Table 40. Registers That Are Sensitive to Changes During Operation
Figure 41. Optional Class D Ferrite Bead Filter
Stereo Audio CODEC
with FLEXSOUND Technology
While many configuration options in the IC can be made
while the device is operating, some registers should
only be adjusted when the corresponding audio path is
disabled. Table 40 lists the registers that are sensitive
during operation. Either disable the corresponding audio
path or set SHDN = 0 while changing these registers.
In applications where speaker leads exceed 20mm,
additional EMI suppression can be achieved by using a
filter constructed from a ferrite bead and a capacitor to
ground (Figure 41). Use a ferrite bead with low DC resis-
tance, high-frequency (> 600MHz) impedance between
100I and 600I, and rated for at least 1A. The capacitor
value varies based on the ferrite bead chosen and the
actual speaker lead length. Select a capacitor less than
1nF based on EMI performance.
An input capacitor, C
impedance of the IC line inputs forms a highpass filter
that removes the DC bias from an incoming analog
110
0x14 to 0x17, 0x1C to 0x1F
0x10 to 0x13, 0x19 to 0x1B
IN
0x50 to 0xC7
0x24 to 0x29
REGISTER
0x18, 0x20
, in conjunction with the input
Optional Ferrite Bead Filter
Component Selection
Input Capacitor
MAX9888
SPK_N
SPK_P
signal. The AC coupling capacitor allows the amplifier
to automatically bias the signal to an optimum DC level.
Assuming zero-source impedance, the -3dB point of the
highpass filter is given by:
Choose C
quency of interest. For best audio quality use capacitors
whose dielectrics have low-voltage coefficients, such as
tantalum or aluminum electrolytic. Capacitors with high-
voltage coefficients, such as ceramics, may result in
increased distortion at low frequencies.
Use capacitors with an ESR less than 100mI for optimum
performance. Low-ESR ceramic capacitors minimize the
output resistance of the charge pump. Most surface-
mount ceramic capacitors satisfy the ESR requirement.
For best performance over the extended temperature
range, select capacitors with an X7R dielectric.
Digital Signal Processing Coefficients
IN
Digital Audio Interface Configuration
so that f
Clock Control Registers
Digital Passband Filters
f
DESCRIPTION
-3dB
Charge-Pump Capacitor Selection
Analog Mixers
-3dB
=
2 R C
is well below the lowest fre-
π
IN IN
1