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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 V
SS
.
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:
R
L
= load impedance
R
s
= series resistance of filter coil
P
o(1%)
= output power just at clipping.
The output power at THD = 10 %: P
o(10%)
= 1.25 × P
o(1%)
.
15.4 Reference design
The reference 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.
P
o(1%)
R
L
R
L
R
ds(on)
R
s
++()
------------------------------------------------
V
P
×
2
2R
L
×
----------------------------------------------------------------------
=
I
O(max)
V
P
[]
R
L
R
ds(on)
R
s
++
-------------------------------------------
=