MAX9791AETI+ Maxim Integrated Products, MAX9791AETI+ Datasheet - Page 25

• Manufacturer Part Number: MAX9791AETI+
• Description: IC AMP AUDIO 2.2W STER D 28TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class Dr

Specifications of MAX9791AETI+

• Output Type: 2-Channel (Stereo) with Stereo Headphones and Subwoofer
• Max Output Power X Channels @ Load: 2.2W x 2 @ 4 Ohm; 180mW x 2 @ 32 Ohm
• Voltage - Supply: 4.5 V ~ 5.5 V
• Features: Depop, LDO, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PVDD powers the speaker amplifiers. PVDD ranges
from 2.7V to 5.5V. AVDD and PVDD must be tied
together. If LDO is enabled, set AVDD and PVDD as
specified in the Line Regulation row of the Electrical
Characteristics table. Bypass PVDD with a 0.1µF
capacitor to PGND. Apply additional bulk capacitance
at the device if long input traces between PVDD and
the power source are used.
The headphone amplifiers are powered from HPVDD
and CPVSS. HPVDD is the positive supply of the head-
phone amplifiers and ranges from 2.7V to 5.5V. Bypass
HPVDD with a 10µF capacitor to PGND. CPVSS is the
negative supply of the headphone amplifiers. Bypass
CPVSS with a 1µF capacitor to PGND. The charge
pump inverts the voltage at HPVDD, and the resulting
voltage appears at CPVSS. A 1µF capacitor should be
connected between C1N and C1P.
The internal LDO and the remainder of the device are
powered by AVDD. AVDD ranges from 2.7V to 5.5V.
AVDD and PVDD must be tied together. If LDO is
enabled, set AVDD and PVDD as specified in LDO line
regulation. Bypass AVDD with a 0.1µF capacitor to
GND and two 1µF capacitors to GND. Note additional
bulk capacitance is required at the device if long input
traces between AVDD and the power source are used.
Figure 12. Input Coupling Capacitor-Induced THD+N vs.
Frequency
Amplifiers with DirectDrive Headphone Amplifiers
Speaker Amplifier Power-Supply Input (PVDD)
Positive Power Supply and LDO Input (AVDD)
-100
-50
-60
-70
-80
-90
Headphone Amplifier Power-Supply Input
INPUT COUPLING CAPACITOR-INDUCED THD+N
10
vs. FREQUENCY (HEADPHONE MODE)
0402 6.3V X5R 10% 1µF
0603 10V X7R 10% 1µF
Windows Vista-Compliant Class D Speaker
______________________________________________________________________________________
FREQUENCY (kHz)
Component Selection
0603 10V X5R 10% 1µF
100
0805 50V X7R 10% 1µF
(HPVDD and CPVSS)
V
FS = 1V
R
OUT
L
=32Ω
- -3dBFS
RMS
1000
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 signal
to an optimum DC level. Assuming zero source imped-
ance, the -3dB point of the highpass filter is given by:
R
Choose C
frequency of interest. Setting f
the amplifier’s low frequency response. Use capaci-
tors with adequately low-voltage coefficients (see
Figure 12). Capacitors with higher voltage coeffi-
cients, such as ceramics, result in increased distor-
tion at low frequencies.
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 13. Speaker RF Immunity
IN_
is the amplifier’s external input resistance value.
IN_
-100
-110
-120
-130
-10
-20
-30
-40
-50
-60
-70
-80
-90
0
such that f
0
f
500
Charge-Pump Capacitor Selection
-3
SPEAKER RF IMMUNITY
dB
IN_
IN_
1000
=
vs. FREQUENCY
FREQUENCY (MHz)
), in conjunction with the ampli-
-3dB
), forms a highpass filter that
2
RIGHT
π
LEFT
R
1500
IN
is well below the lowest
1
_
Flying Capacitor (C1)
C
-3dB
2000
IN
_
too high affects
2500
Input Filtering
3000
25