max9779etit Maxim Integrated Products, Inc., max9779etit Datasheet - Page 12

• Manufacturer Part Number: max9779etit
• Description: Max9779 2.6w Stereo Audio Power Amplifier And Directdrive Headphone Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

The headphone sense input (HPS) monitors the head-
phone jack and automatically configures the device
based upon the voltage applied at HPS. A voltage of
less than 0.8V sets the device to speaker mode. A volt-
age of greater than 2V disables the bridge amplifiers
and enables the headphone amplifiers.
For automatic headphone detection, connect HPS to the
control pin of a 3-wire headphone jack as shown in
Figure 5. With no headphone present, the output imped-
ance of the headphone amplifier pulls HPS low. When a
headphone plug is inserted into the jack, the control pin
is disconnected from the tip contact and HPS is pulled
to V
The MAX9779 features an internally generated, power-
supply independent, common-mode bias voltage of
1.8V referenced to GND. BIAS provides both click-and-
pop suppression and sets the DC bias level for the
amplifiers. Choose the value of the bypass capacitor as
described in the BIAS Capacitor section. No external load
should be applied to BIAS. Any load lowers the BIAS volt-
age, affecting the overall performance of the device.
2.6W Stereo Audio Power Amplifier and
DirectDrive Headphone Amplifier
Figure 4. Distortion Contributed by DC-Blocking Capacitors
12
DD
______________________________________________________________________________________
through a 10µA current source.
0.0001
0.001
0.01
0.1
10
1
10
Headphone Sense Input (HPS)
TO DC-BLOCKING CAPACITORS
ALUM/ELEC
ADDITIONAL THD+N DUE
100
FREQUENCY (Hz)
TANTALUM
1k
10k
100k
BIAS
The MAX9779 features an internally set, selectable gain.
The GAIN1 and GAIN2 inputs set the maximum gain
of the MAX9779 speaker and headphone amplifiers
(Table 1).
The MAX9779 features a 0.2µA, low-power shutdown
mode that reduces quiescent current consumption and
extends battery life. Driving SHDN low disables the
drive amplifiers, bias circuitry, and charge pump, and
drives BIAS and all outputs to GND. Connect SHDN to
V
The MAX9779 speaker amplifiers feature Maxim’s com-
prehensive, industry-leading click-and-pop suppres-
sion. During startup, the click-pop suppression circuitry
eliminates any audible transient sources internal to the
device. When entering shutdown, both amplifier out-
puts ramp to GND quickly and simultaneously.
Figure 5. HPS Configuration
DD
for normal operation.
SHUTDOWN
CONTROL
HPOUTL
HPOUTR
MAX9779
HPS
Click-and-Pop Suppression
1kΩ
10µA
1kΩ
V
DD
Speaker Amplifier
Gain Selection
20
14
13
Shutdown