TDA8954 NXP Semiconductors, TDA8954 Datasheet - Page 26

• Manufacturer Part Number: TDA8954
• Description: The TDA8954 is a stereo or mono high–efficiency Class D audio power amplifier in asingle IC featuring low power dissipation
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8954_1
Product data sheet
14.6 Pumping effects
14.7 Application schematic
The derating curves for power dissipation (for several R
Figure
maximum allowable power dissipation for a given heatsink size can be derived, or the
required heatsink size can be determined, at a required power dissipation level; see
Figure
In a typical stereo single-ended configuration, the TDA8954 is supplied by a symmetrical
supply voltage (e.g. V
configuration, a ‘pumping effect’ can occur. During one switching interval, energy is taken
from one supply (e.g. V
(e.g. V
across the output capacitors of that voltage supply source increases and the supply
voltage is pumped to higher levels. The voltage increase caused by the pumping effect
depends on:
Pumping effects should be minimized to prevent the malfunctioning of the audio amplifier
and/or the voltage supply source. Amplifier malfunction due to the pumping effect can
trigger UVP, OVP or UBP.
The most effective way to avoid pumping effects is to connect the TDA8954 in a mono
full-bridge configuration. In the case of stereo single-ended applications, it is advised to
connect the inputs in anti-phase (see
be adapted; for example, by increasing the values of the supply line decoupling
capacitors.
Notes on the application schematic:
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•
•
•
•
•
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R
th(h-a)
Speaker impedance
Supply voltage
Audio signal frequency
Value of supply line decoupling capacitors
Source and sink currents of other channels
Connect a solid ground plane around the switching amplifier to avoid emissions
Place 100 nF capacitors as close as possible to the TDA8954 power supply pins
Connect the heatsink to the ground plane or to VSSPn using a 100 nF capacitor
Use a thermally conductive, electrically non-conductive, Sil-Pad between the
TDA8954 heat spreader and the external heatsink
The heat spreader of the TDA8954 is internally connected to VSSA
Use differential inputs for the most effective system level audio performance with
unbalanced signal sources. In case of hum due to floating inputs, connect the
shielding or source ground to the amplifier ground.
SS
12. A maximum junction temperature T
12.
) and vice versa. When the voltage supply source cannot sink energy, the voltage
(thermal resistance from heatsink to ambient) = 10.3 − (0.9 + 1) = 8.4 K/W
Rev. 01 — 24 December 2009
DD
DD
= +41 V and V
), while a part of that energy is returned to the other supply line
Section 8.5 on page
SS
= −41 V). When the amplifier is used in an SE
j
= 150 °C is taken into account. The
2 × 210 W class-D power amplifier
th(j-a)
14). The power supply can also
values) are illustrated in
TDA8954
© NXP B.V. 2009. All rights reserved.
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