AN10436 PHILIPS [NXP Semiconductors], AN10436 Datasheet - Page 43

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

NXP Semiconductors
AN10436_1
Application note
4.4 Unregulated or weak power supply
With this method, OUT1 and OUT2 are out of phase to minimize the pumping effect. The
inversion of one of the outputs will also halve the peak current drawn from the power
supply at a low audio frequency.
Remark: Do not forget to change the polarity of the speaker connection of channel 2 to
get the original phase of the signal from the speaker.
The voltage ripple of an unregulated power supply can be quite significant, due to:
Therefore, when operating from an asymmetrical supply, this voltage ripple will cause
asymmetrical clipping. This might trigger also the UBP (UnBalance Protection) when the
voltage ripple exceeds either −20 % or +33 % of the nominal supply voltage (see also
Section
an SMPS or a 50 Hz / 60 Hz transformer) might need some attention to minimize the load,
the line and the cross regulation.
The voltage dip during a transient from no load condition to full load condition should be
considered. The average supply current in full load for a stereo amplifier can be estimated
as follows:
Where:
SE: I
BTL: I
Fig 40. Inverting the phase of one output and input (of channel 2)
•
•
•
P
η
po
o
The output impedance (load regulation).
A variation on the AC mains (line regulation).
A cross regulation in a multiple output SMPS.
P(avg)
= RMS output power per channel (W)
= output power efficiency, audio amplifier
P(avg)
2.6.6). Therefore, any unregulated power supply (an auxiliary voltage from either
=
=
-------------------
η
2 P
po
-------------------
η
⋅
⋅
po
V
P
o
⋅
P
o
V
IN1N
IN2N 14
IN1P 2
IN2P
Rev. 01 — 12 December 2007
P
3
15
TDA8932B/33(B)
27
22
OUT1
OUT2
TDA8932B/33(B) Class-D audio amplifier
LP
FILTER
LP
FILTER
C15
C24
AN10436
010aaa064
© NXP B.V. 2007. All rights reserved.
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