AS3561
Class-H Stereo Headphone Amplifier
General Description
The AS3561 is a Class-H stereo headphone amplifier optimized
for usage within portable devices. The Class-H supply rail
adaptation is implemented by an integrated DCDC buck
converter that takes its input directly from the battery. The
continuous adoption of supply rails is done according to the
input signal swing and load conditions. This architecture
implements significant power savings compared to traditional
Class-AB amplifiers.
An I²C control interface is implemented for a 32-step volume
control including a mute function for each channel separately.
The integrated charge pump generates a symmetric negative
supply for true ground output signal levels without the need of
output coupling capacitors. In addition it helps to lower the
overall pop noise of the amplifier.
A supervisory circuit is included for overtemperature and
short-circuit protection.
Differential inputs together with output ground sensing
guarantees very low noise sensitivity.
Ordering Information
and
Content Guide
appear at end of
datasheet.
Key Benefits & Features
The benefits and features of the AS3561 Class-H stereo
headphone amplifier, are listed below:
Figure 1:
Added value of using AS3561
Benefits
Highly optimized system power
consumption
Popless startup and mute/unmute
Full digital system control
Direct Li-Ion battery operation
No DC blocking capacitors
Highest Noise Immunity
PCB area optimized
Features
H-Class amplifier with integrated DCDC buck converter
• 2x30mW, 0.02% THD @ 16Ω
• 100dB SNR @ 0.9Vrms
• 1mA quiescent with both channels enabled
Ultra low DC offset
I²C control interface
Wide supply range 2.3V to 5.5V
Charge pump for true ground headphone operation
Two fully differential stereo inputs with ground sensing input
Package: 0.4mm Pitch WL-CSP (1.615 x 1.615mm)
ams Datasheet
[v1-07] 2014-Sep-26
Page 1
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AS3561 −
General Description
Applications
The AS3561 applications include:
• Mobile Phones
• Portable Navigation Devices
• Media Devices
Block Diagram
The functional blocks of this device for reference are
shown below:
Figure 2:
AS3561 Block Diagram
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[v1-07] 2014-Sep-26
AS3561 −
Pin Assignments
Pin Assignments
Figure 3:
Pin Assignments (Top View)
The AS3561 pin assignments are described below:
Pin Descriptions
Figure 4:
Pin Descriptions
Pin Name
SW
AVDD
HPL
INLN
Pin Number
A1
A2
A3
A4
Description
Buck converter switching node
Primary power supply for device
Left channel headphone amplifier output
Inverting left input for differential signals;
Connect to left input signal through 2.2μF capacitor for single-ended
input applications
Main Ground for headphone amplifiers, DC/DC converter, and charge
pump
Charge pump positive flying cap; connect to 2.2μF flying capacitor
Power supply for headphone amplifier (DC/DC output node)
Non-inverting left input for differential signals;
Connect to ground through 2.2μF capacitor for single-ended input
applications
AGND
CPP
HPVDD
INLP
B1
B2
B3
B4
ams Datasheet
[v1-07] 2014-Sep-26
Page 3
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AS3561 −
Pin Assignments
Pin Name
CPN
HPVSS
SGND
INRP
SDA
SCL
HPR
INRN
Pin Number
C1
C2
C3
C4
D1
D2
D3
D4
Description
Charge pump negative flying cap; connect to 2.2μF flying capacitor
Charge pump output; connect 2.2μF capacitor to GND
Ground sense; connect to headphone jack ground
Non-Inverting right input for differential signals;
Connect to right input signal through 2.2μF capacitor for single-ended
input applications
I²C Data; 1.8V logic compliant
I²C Clock; 1.8V logic compliant
Right channel headphone amplifier output
Inverting right input for differential signals;
Connect to ground through 2.2μF capacitor for single-ended input
applications
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[v1-07] 2014-Sep-26
AS3561 −
Absolute Maximum Ratings
Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device. These are
stress ratings only. Functional operation of the device at these
or any other conditions beyond those indicated under
Operating Conditions
is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Figure 5:
Absolute Maximum Ratings
Symbol
AVDD
HPVDD
SGND
Parameter
Supply voltage
Amplifier supply voltage
Min
-0.3
-0.3
-0.3
Max
7
2.0
0.3
HPVDD + 0.3V
7.0
HPVDD + 0.5
±200
Unit
V
V
V
V
V
V
mA
Comments
for 1ms peaks
Differential Input voltage
Input voltage at SCL, SDA
Breakdown voltage at
amplifier outputs
Input current (latchup
immunity)
HPVSS - 0.3V
-0.3
-0.5
Norm: JEDEC 78
Continuous Power Dissipation
Continuous power
dissipation
Continuous power
dissipation derating factor
TBD
TBD
Electrostatic Discharge
ESD HBM
ESD MM
ESD CDM
±2
±100
±500
kV
V
V
Norm: MIL 883 E
Method 3015
Norm: JEDEC JESD
22-A115-A level A
Norm: JEDEC JESD
22-C101C
mW
mW/°C
P
T
(1)
P
DERATE
(2)
ams Datasheet
[v1-07] 2014-Sep-26
Page 5
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