APA2606 Datasheet, PDF (20/27 Pages) Anpec Electronics Coropration – 2.8W Stereo Class-D Audio Power Amplifier and Class AB Headphone Driver

APA2606
Application Information (Cont.)
Ferrite Bead Selection
If the traces form APA2606 to speaker are short, the ferrite
bead filters can reduce the high frequency radiated to
meet the FCC & CE required.
A ferrite that has very low impedance at low frequencies
and high impedance at high frequencies (above 1 MHz)
is recommended.
Output Low-Pass Filter
If the traces form APA2606 to speaker are short, it doesn’t
require output filter for FCC & CE standard.
A ferrite bead may be needed if it’s failing the test for FCC
or CE tested without the LC filter. The figure 3 is the sample
for added ferrite bead; the ferrite shows choosing high
impedance in high frequency.
OUTP ^36µH
1µF
OUTN ^36µH
8Ω
1µF
Figure 4. LC output filter for 8Ω speaker
Ferrite
V_ON Bead
1nF
Ferrite
Bead
4Ω
V_OP
1nF
OUTP ^18µH
2.2µF
OUTN ^18µH
4Ω
2.2µF
Figure 5. LC output filter for 4Ω speaker
Figure 3. Ferrite bead output filter
Figure 4 and 5’s low pass filter cut-off frequency are 25kHz
(F_C).
f_C(lowpass) =
1
(5)
2π LC
Figure 4 and 5 are examples for added the LC filter
(Butterworth), it’s recommended for the situation that the
trace form amplifier to speaker is too long and needs to
eliminate the radiated emission or EMI.
Power-Supply Decoupling Capacitor, C_S
The APA2606 is a high-performance CMOS audio ampli-
fier that requires adequate power supply decoupling to
ensure the output total harmonic distortion (THD) is as
low as possible. Power supply decoupling also prevents
the oscillations being caused by long lead length be-
tween the amplifier and the speaker.
Copyright © ANPEC Electronics Corp.
20
Rev. A.6 - MAr., 2013
www.anpec.com.tw