MAX9790AETJ+ Maxim Integrated Products, MAX9790AETJ+ Datasheet - Page 18

• Manufacturer Part Number: MAX9790AETJ+
• Description: IC AMP AUDIO 2W STER AB 32TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class ABr

Specifications of MAX9790AETJ+

• Output Type: 2-Channel (Stereo) with Stereo Headphones
• Max Output Power X Channels @ Load: 2W x 2 @ 4 Ohm; 100mW x 2 @ 16 Ohm
• Voltage - Supply: 4.5 V ~ 5.5 V
• Features: Depop, Mute, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 32-TQFN Exposed Pad
• For Use With: MAX9789AEVKIT+ - EVALUATION KIT FOR MAX9789A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Windows Vista-Compliant, Stereo Class AB Speaker
Amplifiers and DirectDrive Headphone Amplifiers
The headphone amplifiers are powered from HPV
and PV
phone amplifiers and ranges from 3.0V to 5.5V. Bypass
HPV
negative supply of the headphone amplifiers. Bypass
PV
CPV
CPV
same potential as HPV
capacitor to PGND. The charge pump inverts the volt-
age at CPV
CPV
C1N and C1P.
The internal LDO and the remainder of the device is
powered by V
Bypass V
1µF capacitors in parallel to GND. Note additional bulk
capacitance is required at the device if long input
traces between V
The input capacitor (C
fier input resistance (R
removes the DC bias from the incoming signal. The AC-
coupling capacitor allows the amplifier to bias the sig-
nal 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 adequately low
voltage coefficient dielectrics, such as 1206-sized X7R
ceramic capacitors. Capacitors with higher voltage
coefficients result in increased distortion at low fre-
quencies (see Figure 8).
18
IN
SS
SS
DD
DD
is the amplifier’s internal input resistance value
______________________________________________________________________________________
SS
-3dB
with a 1µF capacitor to PGND. Connect PV
. A 1µF capacitor must be connected between
. The charge pump is powered by CPV
SS
with a 10µF capacitor to PGND. PV
ranges from 3.0V to 5.5V and should be the
-3dB
. HPV
DD
is well below the lowest frequency of interest.
DD
with a 0.1µF capacitor to GND and two
too high affects the amplifier’s low fre-
Headphone Amplifier Power-Supply
, and the resulting voltage appears at
DD
DD
DD
Power Supply and LDO Input (V
f
. V
−
is the positive supply of the head-
3
and the power source are used.
dB
DD
IN
IN
DD
), in conjunction with the ampli-
=
), forms a highpass filter that
ranges from 4.5V to 5.5V.
. Bypass CPV
2π
Input (HPV
R C
IN IN
1
DD
Input Filtering
DD
and PV
with a 1µF
SS
IN
is the
SS
such
DD
DD
SS
DD
to
)
)
.
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 and headphone
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.
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. Connect a 1µF capacitor between
C1P and C1N.
Figure 8. Input Coupling Capacitor-Induced THD vs.
Frequency (Headphone Mode)
-50
-55
-60
-65
-70
-75
-80
-85
-90
INPUT COUPLING CAPACITOR-INDUCED THD+N
10
vs. FREQUENCY (HEADPHONE MODE)
0805 25V X7R 10% 1μF
Charge-Pump Capacitor Selection
0402 6.3V X5R 10% 1μF
1206 25 X7R 10% 1μF V
0603 10V X5R 10% 1μF
FREQUENCY (Hz)
100
Flying Capacitor (C1)
FS = 1V
R
OUT
L
= 32Ω
= 3dB FS
RMS
BIAS Capacitor
BIAS
1000
improves