MAX9787ETI MAXIM [Maxim Integrated Products], MAX9787ETI Datasheet - Page 11

• Manufacturer Part Number: MAX9787ETI
• Description: 2.2W Stereo Audio Power Amplifier with Analog Volume Control
• Manufacturer: MAXIM [Maxim Integrated Products]

Table 3. Suggested Capacitor Manufacturers
Thermal-overload protection limits total power dissipa-
tion in these devices. When the junction temperature
exceeds +160°C, the thermal-protection circuitry dis-
ables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous ther-
mal-overload conditions as the device heats and cools.
The MAX9787 speaker amplifiers are powered from
PV
tive supply of the amplifiers. Connect V
charge pump is powered by CPV
the same potential as PV
the voltage at CPV
appears at CPV
ered by V
The input capacitor (C
fier input resistance (R
removes the DC bias from an incoming signal (see the
Typical Operating Circuit). The AC-coupling capacitor
allows the amplifier to bias the signal to an optimum DC
level. Assuming zero source impedance, the -3dB point
of the highpass filter is given by:
R
given in the Electrical Characteristics. Choose C
that f
Setting f
quency response. Use capacitors with low-voltage
coefficient dielectrics, such as tantalum or aluminum
electrolytic. Capacitors with high-voltage coefficients,
such as ceramics, may result in increased distortion at
low frequencies.
Taiyo Yuden
TDK
IN
DD
is the amplifier’s internal input resistance value
-3dB
. PV
-3dB
DD
DD
SUPPLIER
is well below the lowest frequency of interest.
.
ranges from 4.5V to 5.5V. V
too high affects the amplifier’s low-fre-
SS
f
. The remainder of the device is pow-
−
______________________________________________________________________________________
3
dB
DD
IN
=
IN
), in conjunction with the ampli-
, and the resulting voltage
), forms a highpass filter that
2π
DD
Component Selection
R C
. The charge pump inverts
IN IN
1
2.2W Stereo Audio Power Amplifier
DD
Power Supplies
. CPV
800-348-2496
807-803-6100
SS
PHONE
Input Filtering
SS
to CPV
DD
is the nega-
should be
with Analog Volume Control
IN
SS
. The
such
BIAS is the output of the internally generated DC bias
voltage. The BIAS bypass capacitor, C
PSRR and THD+N by reducing power supply and other
noise sources at the common-mode bias node, and
also generates the clickless/popless, startup/shutdown
DC bias waveforms for the speaker amplifiers. Bypass
BIAS with a 1µF capacitor to GND.
Use capacitors with an ESR less than 100mΩ for opti-
mum performance. Low-ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric.
lists suggested manufacturers.
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. A
C1 value that is too small degrades the device’s ability
to provide sufficient current drive, which leads to a loss
of output voltage. Increasing the value of C1 improves
load regulation and reduces the charge-pump output
resistance to an extent. See the Output Power vs.
Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics. Above
2.2µF, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
The output capacitor value and ESR directly affect the
ripple at CPV
output ripple. Likewise, decreasing the ESR of C2
reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output power levels. See the Output Power
vs. Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics.
847-925-0899
847-390-4405
FAX
SS
. Increasing the value of C2 reduces
Charge-Pump Capacitor Selection
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Output Capacitor (C2)
Flying Capacitor (C1)
WEBSITE
BIAS Capacitor
BIAS
, improves
Table
11
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