AN10436 PHILIPS [NXP Semiconductors], AN10436 Datasheet - Page 41

• Manufacturer Part Number: AN10436
• Description: TDA8932B/33(B) Class-D audio amplifier
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
4. Power supply
AN10436_1
Application note
4.1.1 Lifetime electrolytic capacitor
4.1 Supply filtering
4.2 Supply GND connection
A CLC phi filter (C1, L1 and C2) is used to keep the High Frequency (HF) currents locally
around the amplifier (see
electrolytic buffer capacitor (C1) should be placed close to the amplifier to minimize the
area of the HF current loops to avoid emission. The ferrite bead (L1) will avoid the flow of
HF currents in (mostly) large supply voltage loops. The analog voltage (V
TDA8932B/33(B) requires an RC filter of 10 Ω (R1) and 100 nF (C3) to avoid the HF noise
entering the analog controller part of the device.
The ambient temperature and the ripple current have the greatest effect on the lifetime of
the aluminium electrolytic capacitors. The output power of an amplifier is assumed often to
be ¼ of the total rated output power. At a power rating of 2 × 3.75 W (¼ × 15 W) the
lifetime is not an issue when general-purpose electrolytic capacitors (with a value of at
least 220 μF) are used.
The best practice to avoid any common ground path with the power supply is to leave the
supply floating. The power supply should be attached to GND at the amplifier side. The
differential input should be grounded at the sound processor and not at the amplifier side.
Fig 38. Supply filtering
POWER
SUPPLY
Rev. 01 — 12 December 2007
C2
R1
10 ohm
FERRITE
Figure
BEAD
L1
C3
38). Two 100 nF SMD capacitors (C8 and C25) and an
C1
V
DDA
pin 8
C25
C8
TDA8932B/33(B) Class-D audio amplifier
29
26
23
20
TDA8932B/33(B)
HF
CURRENTS
27
22
OUT 1
OUT 2
LP
FILTER
LP
FILTER
AN10436
© NXP B.V. 2007. All rights reserved.
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