PAM8202 Datasheet, PDF (7/8 Pages) List of Unclassifed Manufacturers – Tiny Package 2 Watt Class-D Stereo Audio Amplifier

PAM8202
Tiny Package 2 Watt Class-D Stereo Audio Amplifier
FCL = 1/ [2 X Cin X (Rin + 10k)]
FCL is the lower corner on frequency response curve.
Cin is very important consider to the lower frequency performance. The Cin should not be too large with small
speakers as the load, because such small speakers usually can not response with lower frequency, delivering too
much low frequency energy into a small speaker which usually got resonant frequency (Fs) around 150Hz is
meaningless and dangerous. This will easily over drive the small speakers. The movement of speaker cone will be
too much under such condition and this also creates unnecessary distortion on mid-to high frequency range
because the speaker is now operating in non-linear area. Speakers can only generate heat but not low frequency
sound when it is over driven, the will cause speaker or amplifier failure in some cases.
Cin should have 10% tolerance or less because the tolerance can cause the input impedance mismatch at FCL
and below.
Output filter
The L and C on each output node of PAM8202 form the low-pass-filter (LPF), the higher corner frequency (FCH) is
determine by equation below.
FCH = 1/ [2 X sqr (L X C)]
FCH is the higher corner on frequency response curve.
Important Notice
The L-C filters (-12dB/Oct) gives twice much attenuation and lower impedance (means lower insertion loss)
compare to those R-C filters (-6dB), but remember, the FCH above is also the resonant frequency of this LC
network. The quality factor (Q) of this resonant network can be very high, depended on the Q of L and C. The high
resonant Q which is usually caused by open-load can generate a very high voltage on speaker terminal, and the
impedance of the L-C network can be very low, thus induces large amount of current flows from output stage of
PAM8202. This always causes part failure. So Do Not test open-load on any class D amplifier with output filters.
LC filter calculator with output load impedance and cut-off frequency
1
1
f=
2
LC ^{, XL= 2 fL , XC=} 2 fC
Power Analog Microelectronics, Inc.
CONFIDENTIAL. DO NOT DISTRIBUTE OR REPRODUCE WITHOUT PERMISSION FROM P.A.M.
PRELIMIARY DATASHEET
7
PAM8202 Rev. 1.1