6
Input
Input
10K
10K
R
L
Vdd
Speaker
Speaker
0.47 F
0.47 F
C1
C2
Cin
Cin
Rin
Rin
0.47 F
C
0.47 F
C
0.47 F
C
0.47 F
C
33 H
L
33 H
L
33 H
L
33 H
L
Setting Amplifier voltage gain
It is very important to know the maximum output level (0dB) of the signal source connected to a power amplifier in
order to prevent hard clipping during operation.
Gain (max) = Vsupply/ Vin (p-p)
Insufficient voltage gain will cause low output level and maybe not enough to drive speaker properly. On the
other hand, the distortion will be very high if the voltage gain is too high in an audio system.
There is a 10k
input resistor integrated in side IN (input) node, and since the integrated feedback resistor is 100k ,
so the maximum voltage gain of PAM8202 is limited at 10V/V (100k/10k, one output). With an external input resistor
(Rin) placed between signal source & input node, the voltage gain will be
Gain = 100k/ (10k + Rin) = Vsupply/ Vin (p-p)
Actual voltage gain is two times of this calculation because of BTL connection.
Decouple capacitor
PAM8202 is a high performance, high speed class D amplifier, and it requires a 1uF, X7R ceramic decouple
capacitor (C1) placed very close between VDD & GND pins to ensure the total harmonic distortion plus noise
(THD+N) performance is as designed. This is also very important for efficiency and lowering noise floor. Another
100 F to 1000 F main decouple capacitor (C2) should be placed close to supply pin for low frequency
Ecoupling.
Input capacitor
Input capacitor (Cin) blocks the DC voltage between signal source & amplifier to ensure the DC balancing will not
be broken between two systems. It also form a high-pass-filter (HPF) with input resistors (Rin + 10k), the lower corner
frequency (FCL) is determine by equation below.
Fig. 1
IN_L
-OUT_L
+OUT_L
+OUT_R
-OUT_R
IN_R
GND
VDD
Power Analog Microelectronics, Inc.
CONFIDENTIAL. DO NOT DISTRIBUTE OR REPRODUCE WITHOUT PERMISSION FROM P.A.M.
PAM8202 Rev. 1.1
PRELIMIARY DATASHEET
PAM8202
Tiny Package 2 Watt Class-D Stereo Audio Amplifier
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