AN10436 PHILIPS [NXP Semiconductors], AN10436 Datasheet - Page 33

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

NXP Semiconductors
AN10436_1
Application note
3.9.1 EMC considerations
3.8 Output RC snubber network
3.9 Layout recommendations
The voltage across the bootstrap capacitor is equal to V
internal diode). Therefore a voltage rating of 16 V is sufficient for the two bootstrap
capacitors.
Remark: Only the TDA8933T device requires a 1 MΩ across both bootstrap capacitors
for discharging when the power stage becomes floating.
An RC snubber network (see schematic
power stage output (pin 22 and pin 27) after a voltage transition. A proper implementation
of this RC snubber will improve the EMC performance (see
The worst case power dissipation in the snubber resistor R5 (R12) is equal to:
Where:
Example:
Substituting C9 = 470 pF, V
dissipation of 73 mW, requiring an 0805 SMD.
The voltage rating of the snubber capacitors (C9 and C26) should be 25 % higher than the
maximum supply voltage in the application.
The PCB design of an SMA is probably the most difficult part of the design, because it
might affect the audio performance, the EMC performance, the thermal performance, or
even the functionality of the TDA8932B/33(B).
A double-sided PCB with plated through holes and 35 μm copper is recommended, but a
single layer is feasible as well.
Figure 29
audio and EMC performance. The top side of this reference board is used to place the
leaded components and the copper plane for thermal reasons. For more information on
thermal considerations refer to
The bottom side of the double-layer PCB is used to place the SMD components, including
the TDA8932B/33(B) and the majority of the signal tracks (see
P
C9 (C29) = snubber capacitor (F)
V
f
osc
=
P
1 2 ⁄ C9
= supply voltage (V) (V
= oscillator frequency (Hz)
⋅
shows a proposed floor plan of the critical components that contribute to a good
⋅
(
V
P
)
2
⋅ ⋅
Rev. 01 — 12 December 2007
2 f
osc
P
DDP
= 22 V and f
Section
− V
SSP
)
3.9.2.
Section
osc
= 320 kHz in
TDA8932B/33(B) Class-D audio amplifier
3.10) reduces the voltage ringing at the
STAB1
Equation
Figure
− V
Figure 30
F
(forward voltage drop
33).
21, results in a power
AN10436
© NXP B.V. 2007. All rights reserved.
to
Figure
33).
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