ETC PAM8406

PAM8406
Alternative 5W Stereo Audio Amplifier
Key Features
General Description
Alternative Output: Class-D or Class-AB
5W Output at 10% THD with a 2 Load and
5V Power Supply at Class D mode
3W Output at 10% THD with a 4 Load and
5V Power Supply
Filterless, Low Quiescent Current and No
EMI
Low THD+N at Fully Output Range
Superior Low Noise
Efficiency up to 90% with Class D Mode
No Pop At Turn-on/off
Fully Short Circuit Protection With Auto
Recovery
Thermal Shutdown
Few External Components to Save the
Space and Cost
SOP-16L/SOP-16(EP) Package
The PAM8406 is a 5W audio amplifier with an
alternative option between Class-D and Class-AB
output which makes PAM8406 very ideally for the
applications efficiency-EMI compatible.
PAM8406 offers low THD+N, high SNR allowing it
to achieve high-quality sound reproduction. The
f u ll y d i ff e r e n ti a l o u t p u t w it h n e w f i lt e r le s s
architecture(Class D mode) allows the device to
drive the speaker directly , requiring no low-pass
output filters and DC blocking capacitors, thus to
save the system cost and PCB area.
The efficiency of the PAM8406 is up to 90%. It can
e xte nd th e ba tter y life , id ea lly for p or table
applications. The PAM8406 is fully protected
against faults with short circuit protection and
thermal protection.
Applications
The PAM8406 is available in SOP-16L/ SOP16(EP) package.
LCD TVs
Mutimedia Speakers
AM/FM System
DABs
Typical Application
VCC
1 uF
VDD
Cin
Rin
INL
INL
INR
INR
1uF
PVDDL
1uF
PVDDR
+OUT_L
PGNDL
Cin
Rin
MO DE
H: Class D(default)
L: Class AB
-OUT_L
SHDN
-OUT_R
MUTE
PGNDR
MODE
VREF
GND
+OUT_R
1uF
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PAM8406
Alternative 5W Stereo Audio Amplifier
Block Diagram
+
+
-
-
CURRENT
PROTECTION
-
-
+
+
PV DD L
Pin Configuration & Marking Information
Top View
SOP-16/SOP-16(EP)
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
X: Internal Code
A: Assembly Code
T: Testing Code
Y: Year
WW: Week
LL: Internal Code
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PAM8406
Alternative 5W Stereo Audio Amplifier
Pin Descriptions
Pin Number
Pin Name
Description
1
+OUT_L
Left Channel Positive Output
2
PGNDL
Power GND
3
-OUT_L
Left Channel N egative Output
4
PVDDL
Power VDD
5
MUTE
Mute Control Input
6
VDD
Analog VDD
7
INL
Left Channel Input
8
VREF
Internal analog reference, connect a bypass capacitor from VREF to GND
9
MODE
High: Class-D ; Low: Class-AB
10
INR
Right Channel Input
11
GND
Analog GND
12
SH DN
Shutdown Control Input (active low)
13
PVDDR
Power VDD
14
-OUT_R
Right Channel Negative Output
15
PGNDR
Power GND
16
+OUT_R
Right Channel Positive Output
active low
Absolute Maximum Ratings
These are stress ratings only and functional operation is not implied Exposure to absolute
maximum ratings for prolonged time periods may affect device reliability All voltages are with
respect to ground
Supply Voltage ...........................................6.0V
Input Voltage.............................-0.3V to V D D+0.3V
Operation Temperature Range.........-40¡C to 85 ¡C
Maximum Junction Temperature..................150¡C
Operation Junction Temperature.....-40 ¡C to 125¡C
Storage Temperature.....................-65 ¡C to 150¡C
Soldering Temperature....................... 300¡C, 5sec
Recommended Operating Conditions
Supply voltage Range........................ 2.5V to 5.5V
Operation Temperature Range.........-40 ¡C to 85 ¡C
Junction Temperature Range.........-40 ¡C to 125¡C
Thermal Information
Par ameter
Sym bol
Package
Maximum
Unit
Thermal Resistance (Junction to Ambient)
JA
SOP-16
110
¡ C/W
Thermal Resis tance (Junction to Case)
JC
SOP-16
23
¡ C/W
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PAM8406
Alternative 5W Stereo Audio Amplifier
Electrical Characteristic
V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted.
Symbol
Parameter
VIN
Supply Po wer
Te st Condit ions
(Class D)
THD+N=1 %,f=1kHz, RL =2
(Class D)
THD+N=10%,f=1kHz, R L=4
Output Power
THD+N=1 %,f=1kHz, RL =4
THD+N=10%,f=1kHz, R L=8
THD+N=1 %,f=1kHz, RL =8
VDD=5.0V,Po=0.1W ~1 W,R L=8
5 .0
VDD=3.6V
2 .6
VDD=2.5V
1 .3
VDD=5.0V
4 .0
VDD=3.6V
2 .0
VDD=2.5V
1 .0
VDD=5.0V
3.14
VDD=3.6V
1 .5
VDD=2.5V
0.76
VDD=5.0V
2.55
VDD=3.6V
1.45
VDD=2.5V
0.63
VDD=5.0V
1 .8
VDD=3.6V
0.92
VDD=2.5V
0.44
VDD=5.0V
1 .6
VDD=3.6V
0.76
VDD=2.5V
0.36
f=1kHz
VDD=5.0V,Po=0.1W ~2 W,R L=4
Total Harmonic Distortion Plus
V DD=3.6V,Po=0.05W~1W,RL =4
No ise
VDD=5.0V,Po=0.1W ~2 W,R L=2
(Class D)
PSRR
Power Sup ply R ip ple Rejection
0.11
W
W
W
W
W
%
%
0.15
f=1kHz
%
0.11
24
V DD=5 .0V, Inpu ts ac- grounded with
W
0.15
f=1kHz
(Class D)
Gain
0.15
V
0.11
V DD=3.6V,Po=0.05W~1W,RL =2
Gv
MAX UNIT
5.5
VDD=5.0V
VDD=3.6 V,Po=0.05W~0.5W ,RL=8
THD+N
TYP
2.5
THD+N=10%,f=1kHz, R L=2
Po
MIN
f=10 0Hz
-7 0
f=1kHz
-6 5
dB
dB
Cs
Crosstalk
VDD=5V,Po=0.5W,R L=8 ,Gv=24d B
f=1kHz
-9 5
dB
SNR
Sig nal- to-noise ratio
VD D =5V, THD=1%,Gv=24dB
f=1kHz
90
dB
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PAM8406
Alternative 5W Stereo Audio Amplifier
Electrical Characteristic
V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted.
Symbol
Para meter
Vn
Outpu t Noise
Test Conditions
VDD=5V, Inputs ac-g rounded
RL =8 , THD=1 0%
Efficiency
RL =4 , THD=1 0%
RL =2 , THD=1 0%
Quiescent Cu rrent
( Cla ss D)
IQ
Quiescent Cu rrent
(Class AB)
MIN
A-weig hting
100
No A-we ighting
150
UNIT
uV
85
F=1kHz
%
80
10
No L oad
8
VD D=2.5V
6
VD D=5.0V
25
VD D=3.6V
MAX
90
Class D Mode
VD D=5.0V
VD D=3.6V
TYP
No L oad
mA
15
VD D=2.5V
mA
10
IMUTE
Muting Current
VD D=5.0V
VMUT E=0.3V
2.4
mA
ISD
Shu tdown Curr ent
VDD=2.5V to 5.5V
Vsd=0.3V
<1
µA
PMOS
180
NMOS
140
Class D
250
kHz
10
mV
Rdson
Static Drain-to-source On-state
Resistor
I DS=500mA,Vgs=5V
fsw
Switching Frequency
VDD=2.5V to 5.5V
Vos
Output Offset Volta ge
Inp ut AC-GND, V DD=5 V
VI H
En abl e Input High Voltage
VD D=5.0V
VIL
Enable
VD D=5.0V
Input Low Vol tage
VI H
MUTE Inpu t High Voltage
VD D=5.0V
VIL
MUTE Input Low Voltage
VD D=5.0V
VI H
MODE Input High Voltage
VD D=5.0V
VIL
MODE Input Lo w Voltage
VD D=5.0V
OTP
Ove rTemp eratu re Protection
OTH
Over Temp erature Hysterisis
m
1.4
0.4
1.4
0.4
V
V
1.4
0.4
V
150
No Load, Jun ction Temperature
VD D=5V
30
¡C
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PAM8406
Alternative 5W Stereo Audio Amplifier
Typical Operating Characteristics
(TA =25¡C)
V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted.
1. THD+N vs Output Power
2. THD+N vs Output Power
60
60
20
20
V DD=3.6V
%
V DD=3.6V
10
10
5
5
2
%
V DD=2.5V
1
2
V DD=2.5V
1
V DD=5V
0.5
VDD =5V
0.5
0.2
0.2
0.1
0.06
1m
2m
5m
10m
20m
50m
100m
200m
500m
1
0.08
1m
2
2m
5m
10m
20m
50m
W
100m 200m
Class D, R L=8 , f=1kHz
1
2
5
Class D, R L =4 , f=1kHz
3. THD+N vs Output Power
4. THD+N vs Output Power
60
60
20
V DD=3.6V
20
%
500m
W
VDD =5V
10
10
5
5
2
%
2
1
VDD =2.5V
0.5
VDD =2.5V
1
V DD=3.6V
0.2
0.5
VDD =5V
0.1
0.05
0.2
0.02
0.08
1m
2m
5m
10m
20m
50m 100m 200m
500m
1
2
0.01
1m
56
2m
5m
10m
20m
50m
Class D, R L=2 , f=1kHz
5. THD+N vs Output Power
2
10k
20k
+22. 5
+20
d
B
g
2
V DD=2.5V
+17. 5
C IN =0.47uF
+15
+12. 5
VDD =3.6V
0.5
A
0.2
+10
C IN =0.1uF
+7. 5
0.1
+5
0.05
0.02
1m
1
C IN =1uF
+25
V DD=5V
5
1
500m
6. Frequency Response
+27. 5
10
%
200m
Class AB, RL =8 , f=1kHz
60
20
100m
W
W
+2. 5
2m
5m
10m
20m
50m
100m 200m
500m
1
2
+0
20
5
W
50
100
200
500
1k
2k
5k
Hz
Class AB, R L=4 , f=1kHz
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PAM8406
Alternative 5W Stereo Audio Amplifier
Typical Operating Characteristics
(continued)
V DD =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted.
8. THD+N vs Output Power (Class AB)
7. THD+N vs Frequency (Class D)
10
10
5
5
2
2
1
0.5
1
Po=0.5W
0.5
%
0.2
Po=0.3W
0.2
Po=0.5W
0.1
%
Po=0.3W
0.05
0.1
0.02
Po=1W
0.05
0.01
Po=1W
0. 005
0.02
0. 002
0.01
20
50
100
200
500
1k
2k
5k
10k
0. 001
20
20k
50
100
200
Hz
1k
2k
5k
10k
20k
2k
5k
10k
20k
Hz
9.Noise Floor (Class D)
10. Noise Floor (Class AB)
-50
-50
-60
-60
-70
d
B
r
500
-70
d
B
r
-80
-80
-90
-90
A
A
-100
-100
-110
-110
-120
20
50
100
200
500
1k
2k
5k
10k
-120
20
20k
50
100
200
500
1k
H
R L=4 ,Vin=2.5V/3.3V/3.6V/4.2/5V/5.5V
R L=4 ,Vin=2.5V/3.3V/3.6V/4.2/5V/5.5V
11. PSRR (Class D)
+0
T
12. PSRR (Class AB)
+0
TT TT
TTT
T
-10
-10
-20
-20
-30
-30
-40
d
B
T
-40
d
B
-50
-50
-60
-60
-70
-70
-80
-80
-90
-90
-100
20
TT
50
100
200
500
1k
2k
5k
10k
-100
20
20k
Hz
50
100
200
500
1k
2k
5k
10k
20k
Hz
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PAM8406
Alternative 5W Stereo Audio Amplifier
Typical Operating Characteristics
(continued)
V DD =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted.
14. Frequency vs Supply Voltage
13. Quiescent Current vs Supply Voltage
29. 0
270. 0
Clas s D
Clas s A B
265. 0
24. 0
260. 0
19. 0
255. 0
14. 0
250. 0
9. 0
245. 0
240. 0
4. 0
2.0
3.0
4 .0
5.0
2. 0
6.0
3.0
Sup ply Volt age(V )
15.Rds(on) vs Iload
4.0
Supply Volt age(V)
5.0
6. 0
16. Efficiency vs Output Power(Class D)
100
2 70 .0
2 50 .0
P MOS
90
NMOS
80
70
2 30 .0
60
50
2 10 .0
40
1 90 .0
30
20
1 70 .0
2ohm
4ohm
8ohm
10
1 50 .0
0
0
500
1000
1 50 0
2000
0
1000
200 0
3 000
4000
5 000
Ila od(mA )
Po(mW )
17. Output Power vs Power Supply
7000
8ohm
4ohm
2ohm
6000
5000
4000
3000
2000
1000
0
2
3
4
Supply Voltage(V)
5
6
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PAM8406
Alternative 5W Stereo Audio Amplifier
Application Notes
higher than its operation voltage, which will
probably damage the device. Therefore, it's
recommended to use either 4 Ni-MH (Nickel
Metal Hydride) rechargeable batteries or 3 dry or
alkaline batteries.
1. When the PAM8406 works in class D mode
with LC filters, it should be connected with the
speaker before it's powered on, otherwise it will
be damaged easily.
4. One should not make the input signal too
large. Large signal can cause the clipping of
output signal when increasing the volume. This
will damage the device b ecause of big gain of the
PAM8406 .
2. When the PAM8406 works without LC filters,
it's better to add a ferrite chip bead at the
outgoing line of speaker for suppressing the
possible electromagnetic interference.
3. The re co mmend ed o pera tin g voltage is
5.5V. When the PAM8406 is powered with 4
battery cells, it should be noted that the voltage
of 4 new dry or alkaline batteries is over 6.0V,
Test Setup for Performance Testing
Notes
1. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement with AP analyzer .
2. Two 22µH inductors are used in series with load resistor to emulate the small speaker for effic iency
measurement.
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PAM8406
Alternative 5W Stereo Audio Amplifier
Application Information
Maximum Gain
capacitors of different types targeting to different
types of noise on the power supply leads. For
higher frequency transients, spikes, or digital
hash on the line, a good low equivalent-seriesresistance (ESR) ceramic capacitor, typically
1.0µF, works best, placing it as close as possible
to the device VD D terminal. For filtering lowerfrequency noise signa ls, a large capacitor of
20µF (ceramic) or greater is recommended,
placing it near the audio power amplifier.
As sh own in b lock dia gram (pag e 2), the
PAM8406 has two internal amplifier stages. The
first stage's gain is externally con figurable, while
the second stage's is internally fixed. The
closed-loop gain of the first stage is set by
selecting the ratio of Rf to R i while the second
stage's gain is fixed at 2x.The output of amplifier
1 serves as the input to amplifier 2, thus the two
amplifiers produce signals identical in
magnitude, but different in phase by 180¡.
Consequently, the differential gain for the IC is
Input Capacitor (Ci )
Large input capacitors are both expensive and
space hungry for portable designs. Clearly, a
certain sized capacitor is needed to couple in low
frequencies without severe attenu ation. But in
many cases the speakers used in portable
systems, whether internal or external, have little
ability to reproduce signals below 100Hz to
150Hz. Thus, using a large input capacitor may
not increase actual system perfor mance. In this
case, input capacitor (C i ) and input resistance
(R i) of the amplifier form a high-pass filter with
the corner frequency determined by equation
below,
1
f C=
2 Ri Ci
A VD =20*log [2*(R f /R i )]
T h e PA M 8 4 0 6 s e t s m a x i m u m R f = 1 4 2 k ,
minimum Ri =18k , so the maximum closed-gain
is 24dB.
Mode Selection
When mode pin high,it features classD; mode pin
low, it¡s class AB. Mode pin can¡t be floating.
Mute Operation
The MUTE pin is an input for controlling the
output state of the PAM8406. A logic low on this
pin disables the outputs, and a logic high on this
pin enables the outputs. This pin may be used as
a quick disable or enable of the outputs without a
volume fade. Quiescent current is listed in the
electrical characteristic table. The MUTE pin can
be left floating due to the internal pull-up.
In addition to system cost and size, click and pop
perfor mance is affected by the size of the input
coupling capacitor, C i. A larger input coupling
capacitor requires more charge to reach its
quiescent DC voltage (nominally 1/2 V DD ). This
charge comes from the internal circuit via the
feedback and is apt to create pops upo n device
enable. Thus, by minimizing the capacitor size
based on necessary low frequency response,
turn-on pops can be minimized.
Shutdown operation
In order to reduce power consumption while not
in use, the PAM8406 contains shutdown circuitry
to turn off the amplifier's bias circuitry. This
shutdown feature turns the amplifier off when
logic low is applied to the SHDN pin. By switching
the SHDN pin connected to GND, the PAM8406
supply current draw will be minimized in idle
mode. The SHDN pin can be left floating due to
the internal pull-up.
Analog Reference Bypass Capacitor (C BYP )
The Analog Reference Bypass Capacitor (C BYP) is
the most critical capacitor and serves several
important functions. During start-up or recovery
from shutdown mode, C BYP determines the rate at
which the amplifie r sta rts up. Th e se cond
function is to reduce noise caused by the power
supply coupling into the output drive signal. This
noise is from the internal analog reference to the
amplifier, which appears as degraded PSRR and
THD+N.
Power supply decoupling
The PAM8406 is a high performance CMOS
audio amplifier that requires adequate power
supply decoupling to ensure the output THD and
P S R R a s l o w a s p o s s ib le . P o w e r s u p p l y
decoupling affects low frequ ency response.
Optimum decoupling is achieved by using two
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PAM8406
Alternative 5W Stereo Audio Amplifier
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