MAX9791AETI+T Maxim Integrated Products, MAX9791AETI+T Datasheet - Page 23

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

Specifications of MAX9791AETI+T

• 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

The MAX9791/MAX9792 feature a common-mode bias
voltage of 0V. A 0V BIAS allows the MAX9791/MAX9792
to quickly turn on/off with no resulting clicks and pops.
With the HDA CODEC outputs biased and the
MAX9791/MAX9792 inputs sitting as 0V in shutdown
and normal operation, the R
eliminated.
The MAX9791/MAX9792 speaker amplifiers feature
Maxim’s comprehensive, industry leading click-and-
pop suppression. During startup and shutdown, the
click-and-pop suppression circuitry eliminates any
audible transient sources internal to the device.
In conventional single-supply headphone amplifiers,
the output-coupling capacitor is a major contributor of
audible clicks and pops. Upon startup, the amplifier
charges the coupling capacitor to its bias voltage, typi-
cally V
charged to GND; a DC shift across the capacitor
results, which in turn appears as an audible transient at
the speaker. Because the MAX9791/MAX9792 do not
require output-coupling capacitors, no audible transient
occurs.
The MAX9791/MAX9792 headphone amplifiers feature
extensive click-and-pop suppression that eliminates
any audible transient sources internal to the device.
Figure 8. Enabling Either the Speaker or Headphone Amplifier
with a Single Control Pin
Amplifiers with DirectDrive Headphone Amplifiers
DD
CONTROL
SINGLE
/2. During shutdown, the capacitor is dis-
Windows Vista-Compliant Class D Speaker
______________________________________________________________________________________
Click-and-Pop Suppression
SPKR_EN
HP_EN
IN
x C
MAX9791
MAX9792
Headphone Amplifier
IN
Speaker Amplifier
time constant is
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s output. The
filters add cost and size and can decrease efficiency
and THD+N performance. The traditional PWM scheme
uses large differential output swings (2 x PVDD peak-
to-peak) causing large ripple currents. Any parasitic
resistance in the filter components results in a loss of
power, lowering the efficiency.
The MAX9791/MAX9792 do not require an output filter.
The devices rely on the inherent inductance of the speak-
er coil and the natural filtering of both the speaker and
the human ear to recover the audio component of the
square-wave output. Eliminating the output filter results in
a smaller, less costly, and more efficient solution.
Because the frequency of the MAX9791/MAX9792 out-
put is well beyond the bandwidth of most speakers,
voice coil movement due to the square-wave frequency
is very small. For optimum results, use a speaker with a
series inductance > 10µH. Typical 8Ω speakers exhibit
series inductances in the 20µH to 100µH range.
Figure 9. Setting Speaker Amplifier Gain
C
IN1
R
IN1
SPKR_IN_
Applications Information
Filterless Class D Operation
20kΩ
R
FB
MAX9791
AMPLIFIER
CLASS D
MONO
OUT_+
OUT_-
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