2004 May 05 12
Philips Semiconductors Preliminary specification
Power stage 2 x 10 or 1 x 20 W class-D
audio amplifier TDA8928J
15.1 SE application
For a SE application the application diagram as shown in Fig.5 can be used.
15.2 Package ground connection
The heatsink of the TDA8928J is connected internally to VSS.
15.3 Output power
The output power in SE self oscillating class-D applications can be estimated using the formula
The maximum current should not exceed 2 A.
Where:
RL= load impedance
Rs= series resistance of filter coil
Po(1%) = output power just at clipping.
The output power at THD = 10 %: Po(10%) = 1.25 ×Po(1%).
15.4 Reference design
Thereference design for a self oscillating class-D system for the TDA8928J is shown in Fig.5. The Printed-Circuit Board
(PCB) layout is shown in Figs 6, 7 and 8. The bill of materials is given in Section 15.4.2.
Po(1%)
RL
RLRds(on) Rs
++()
------------------------------------------------ VP
×2
2R
L
×
----------------------------------------------------------------------
=
IO(max)
VP
[]
RLRds(on) Rs
++
-------------------------------------------
=