tda8933t-n1 NXP Semiconductors, tda8933t-n1 Datasheet - Page 29

• Manufacturer Part Number: tda8933t-n1
• Description: Tda8933 Class-d Audio Amplifier
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8933_1
Preliminary data sheet
14.7 Thermal behavior (printed-circuit board considerations)
14.8 Pumping effects
R
The heat sink in an application with a TDA8933 is made using the copper on the
printed-circuit board. The TDA8933 uses the four corner leads (pins 1, 16, 17 and 32) for
heat transfer from the die to the PCB. The thermal foldback will limit the maximum junction
temperature to 140 C.
Equation 10
the thermal resistance from junction to ambient.
Where:
The power dissipation is shown in
The thermal resistance, R
copper, FR4 base material in free air with natural convection, is 44 K/W (typ.).
When the amplifier is used in an SE configuration, a so-called ‘pumping effect’ can occur.
During one switching interval, energy is taken from one supply (e.g. V
that energy is delivered back to the other supply line (e.g. V
the power supply cannot sink energy, the voltage across the output capacitors of that
power supply will increase.
The voltage increase caused by the pumping effect depends on:
The pumping effect should not cause a malfunction of either the audio amplifier or the
power supply. For instance, this malfunction can be caused by triggering of the
undervoltage or overvoltage protection of the amplifier.
Pumping effects in an SE configuration can be minimized by connecting audio inputs in
anti-phase and changing the polarity of one speaker, as shown in
th j a
•
•
•
•
•
R
T
T
P = power dissipation (W), which is determined by the efficiency of the TDA8933
j(max)
amb
th(j-a)
Speaker impedance
Supply voltage
Audio signal frequency
Value of decoupling capacitors on supply lines
Source and sink currents of other channels
–
= ambient temperature ( C)
=
= thermal resistance from junction to ambient (K/W)
= maximum junction temperature ( C)
T
----------------------------------- -
shows the relation between the maximum allowable power dissipation P and
j max
P
–
T
amb
Rev. 01 — 15 May 2007
th(j-a)
, of a 2 layer application board (55 mm
Figure 21
(SE) and
Figure 33
SSP1
), and vice versa. When
Class-D audio amplifier
(BTL).
Figure
DDP1
TDA8933
© NXP B.V. 2007. All rights reserved.
45 mm), 35 m
11.
), while a part of
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