TDA8954 NXP Semiconductors, TDA8954 Datasheet - Page 24

• 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
14.3.2 Bridge-Tied Load (BTL)
14.4 External clock
14.5 Heatsink requirements
Maximum output power:
Maximum output current internally limited to 12 A:
Where:
Remark: Note that I
of the current through the load and the ripple current. The value of the ripple current is
dependent on the coil inductance and the voltage drop across the coil.
To ensure duty cycle-independent operation, the external clock frequency is divided by
two internally. The external clock frequency is therefore twice the internal clock frequency
(typically 2 × 335 kHz = 670 kHz).
If several Class D amplifiers are used in a single application, it is recommended that all
the devices run at the same switching frequency. This can be achieved by connecting the
OSC pins together and feeding them from an external oscillator. When using an external
oscillator, it is necessary to force pin OSC to a DC level above SGND. This disables the
internal oscillator and causes the PWM to switch at half the external clock frequency.
The internal oscillator requires an external resistor R
and pin OSCREF. R
The noise generated by the internal oscillator is supply voltage dependent. An external
low-noise oscillator is recommended for low-noise applications running at high supply
voltages.
An external heatsink must be connected to the TDA8954.
Equation 5
of TFB and total thermal resistance from junction to ambient.
P
I
o peak
•
•
•
•
•
•
•
o 0.5%
(
(
P
R
R
R
R
t
f
w(min)
osc
o(0.5 %)
L
DSon(hs)
DSon(ls)
s(L)
: load impedance
)
: oscillator frequency
)
=
: series impedance of the filter coil
=
: minimum pulse width (typical 150 ns, temperature dependent)
--------------------------------------------------------------------------------------------- -
R
defines the relationship between maximum power dissipation before activation
(
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
: output power at the onset of clipping
: low-side R
V
L
------------------------------------------------------------------ -
R
: high-side R
DD
+
L
+
(
R
–
R
DSon hs
V
DSon hs
o(peak)
OSC
SS
Rev. 01 — 24 December 2009
)
(
(
×
DSon
R
must be removed when using an external oscillator.
)
(
DSon
L
)
1 t
should be less than 12 A; see
+
+
–
R
of power stage output DMOS (temperature dependent)
R
DSon ls
of power stage output DMOS (temperature dependent)
w min
DSon ls
(
( )
( )
)
×
)
×
+
0.5f
(
2R
V
2R
osc
DD
s L ( )
L
)
–
V
SS
)
OSC
×
2 × 210 W class-D power amplifier
(
1 t
, connected between pin OSC
Section
–
w min
(
)
8.4.2. I
×
0.5f
TDA8954
© NXP B.V. 2009. All rights reserved.
osc
o(peak)
)
2
is the sum
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(3)
(4)