PAM8945
4.0W CLASS-G AUDIO AMPLIFIER WITH INTEGRATED
BOOST CONVERTER AND BATTERY TRACKING AGC
Description
The PAM8945 is a high-efficiency Class-G audio power
amplifier with an integrated boost converter. It drives up to
4.0W (10% THD+N) into a 4Ω speaker. With 85% typical
efficiency, the PAM8945 helps extend battery life when
playing audio.
The built-in boost converter generates the voltage rail for the
output stage. This provides a louder audio output than a
stand-alone amplifier connected directly to the battery. It also
maintains a consistent loudness, regardless of battery
voltage.
The PAM8945 features battery tracking AGC function which
adjusts the amplifier gain to limit battery current at lower
battery voltage.
The PAM8945 features DC input protection and all outputs
are fully protected against output-to-output shorts. The
PAM8945 is available in tiny W-QFN2030-12 package.
Pin Assignments
(Top View)
BGND
12
PVDD
1
SW
11
10
VBAT
PROVISIONAL PRODUCT
OUT+
2
9
AGC
OUT-
3
8
EN
PGND
4
7
IN+
5
5
5
6
6
5
AGND
IN-
W-QFN2030-12
Features
Applications
Cell Phones
PDA
GPS
Portable Electronics
Speakers
Built-in Battery Tracking Automatic Gain Control (AGC)
High-Efficiency Integrated Boost Converter Over 85%
4.0W into a 4Ω Load at 10% THD
3.2W into a 4Ω Load at 1% THD
Operates from 2.8V to 5.2V
Efficient Class-G Prolongs Battery Life
Minimized ON/OFF Pop Noise
Superior Low Noise
High PSRR
DC Input Protection
Auto-Recovery Short-Circuit Protection
Thermal Shutdown
Available in 2.0mm x 3.0mm 12L W-QFN Package
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and
Antimony-free, "Green" and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total
Br + Cl) and <1000ppm antimony compounds.
PAM8945
Document number: DS38267 Rev. 2 - 2
1 of 9
www.diodes.com
June 2016
© Diodes Incorporated
PAM8945
Typical Applications Circuit
2.2μH
2.8V to 5.2V
100μF
+ 10μF
VBAT
ON
OFF
EN
OUT+
IN+
Audio Input
IN-
AGC AGND
OUT-
BGND
1μF
SW PVDD
PGND
10μF
PROVISIONAL PRODUCT
AGC
Pin Descriptions
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
Pin Name
PVDD
OUT+
OUT-
PGND
AGND
IN-
IN+
EN
AGC
VBAT
SW
BGND
Description
Boost Converter Output and Amplifier Power Supply
Amplifier Positive Audio Output
Amplifier Negative Audio Output
Power Ground
Analog Ground
Negative Audio Input
Positive Audio Input
Shutdown Terminal for the Chip
AGC Setting Gain
Supply Voltage
Boost Convertor Switching
Power Ground
PAM8945
Document number: DS38267 Rev. 2 - 2
2 of 9
www.diodes.com
June 2016
© Diodes Incorporated
PAM8945
Functional Block Diagram
V
BAT
SW
EN
Bias
Boos t Conv ertor
PVDD
PROVISIONAL PRODUCT
IN+
+
AGC
-
PWM
Modulator
Gate
Driv e
Gate
Driv e
OUT+
OUT-
IN-
UVLO
AGC
VREF
OSC
SCP
OTP
DCP
Startup
Protec tion
AGND
BGND
PGND
Absolute Maximum Ratings
(@T
A
= +25°C, unless otherwise specified.)
Symbol
V
BAT
V
I
T
A
T
J
T
STG
Supply Voltage
Input Voltage, EN, IN+, IN-, AGC
Operating Free-air Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
Parameter
Value
-0.3 to 6.0
-0.3 to V
BAT
+ 0.3
-40 to +85
-40 to +150
-65 to +150
Unit
V
V
°C
°C
°C
Recommended Operating Conditions
(@T
A
= +25°C, unless otherwise specified.)
Symbol
V
BAT
V
IH
V
IL
T
A
Supply Voltage
High-Level Input Voltage
Low-Level Input Voltage
Operating Free-Air Temperature
EN
EN
Parameter
Min
2.8
1.3
GND
-40
Max
5.2
V
BAT
0.6
+85
Unit
V
V
V
°C
Thermal Information
Symbol
θ
JA
θ
Jc
Parameter
Thermal Resistance (Junction to Ambient)
Thermal Resistance (Junction to Case)
Package
W-QFN2030-12
W-QFN2030-12
Max
62
11
Unit
°C/W
PAM8945
Document number: DS38267 Rev. 2 - 2
3 of 9
www.diodes.com
June 2016
© Diodes Incorporated
PAM8945
Electrical Characteristics
Symbol
V
BAT
P
O
Parameter
Supply Voltage
Output Power
Total Harmonic
Distortion Plus
Noise
Power Supply Ripple
Rejection
Signal-To-Noise Ratio
Peak Output Voltage
Boost Convertor Auto-Pass
Through Threshold
Output Noise
Efficiency
Quiescent Current
Shutdown Current
Static Drain-to-Source On-
State Resistor
—
THD+N=10%, f=1kHz
THD+N=1%, f=1kHz
P
O
=1.0W, R
L
=8Ω
P
O
=2W, R
L
=4Ω
V
BAT
=3.6V, Input AC -
ground with C=1μF
A-weighting
V
BAT
=3.6V
—
Input AC-ground
R
L
=8Ω, P
O
=1W
V
BAT
=3.6V
V
BAT
=2.8V to 5.2V
High Side PMOS,
I=500mA
Low Side NMOS,
I=500mA
V
BAT
=2.8V to 5.2V
Class D
G
V
R
IN
V
OS
I
PEAK
t
ON
V
IH
Closed-Loop Gain
Input Impedance
Output Offset Voltage
Convertor SW Peak Current
Start-Up Time From EN
En Input High Voltage
—
A
v
=20dB
Input AC-ground
V
BAT
=3.6V
—
V
BAT
=5V
V
BAT
=5V
—
—
—
—
—
—
—
V
BAT
=3.6V
f=1kHz
f=217Hz
PSRR
SNR
V
OP
V
O_TH
V
N
η
I
Q
I
SD
f=1kHz
f=10kHz
THD+N=1%
f=1kHz
—
No A-weighting
A-weighting
f=1kHz
No Load
EN=0V
V
BAT
=5V
V
BAT
=5V
Boost
f
SW
Switching Frequency
(@VBAT=3.6V, AGC=GND, T
A
= +25°C, R
L
=4Ω+33µH, unless otherwise specified.)
Test Conditions
Min
2.8
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
1.3
—
Typ
—
4.0
3.2
0.07
0.15
70
70
67
95
5.75
2
100
60
86
4
—
260
160
1,200
300
20
24
—
4
6
—
—
Max
5.2
—
—
—
—
—
—
—
—
—
—
—
—
—
—
1
—
—
—
kHz
—
—
—
20
—
—
—
dB
KΩ
mV
A
ms
V
dB
V
V(PEAK)
μV
%
mA
μA
mΩ
mΩ
dB
Unit
V
W
W
%
PROVISIONAL PRODUCT
THD+N
R
DS(ON)
V
IL
En Input Low Voltage
0.6
PAM8945
Document number: DS38267 Rev. 2 - 2
4 of 9
www.diodes.com
June 2016
© Diodes Incorporated
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