TDA8922B
Philips Semiconductors
2 × 50 W class-D power amplifier
Maximum current (internally limited to 5 A):
V × (1 – t
× f
)
osc
P
min
I
=
(2)
-----------------------------------------------------
o(peak)
R + 0.6
L
BTL:
2
R
L
× 2V × (1 – t
× f
)
osc
-------------------
P
min
R + 1.2
L
P
=
(3)
(4)
--------------------------------------------------------------------------------------------
2 × R
o(1%)
L
Maximum current (internally limited to 5 A):
2V × (1 – t
× f
)
osc
P
min
I
=
---------------------------------------------------------
R + 1.2
o(peak)
L
Variables:
RL = load impedance
fosc = oscillator frequency
tmin = minimum pulse width (typical 150 ns).
VP = single-sided supply voltage (so, if supply is ±30 V symmetrical, then VP = 30 V)
Po(1%) = output power just at clipping
Po(10%) = output power at THD = 10 %
Po(10%) = 1.24 × Po(1%)
.
13.4 External clock
When using an external clock the following accuracy of the duty cycle of the external clock
has to be taken into account: 47.5 % < δ < 52.5 %.
If two or more class-D amplifiers are used in the same audio application, it is strongly
recommended that all devices run at the same switching frequency.This can be realized
by connecting all OSC pins together and feed them from an external central oscillator.
Using an external oscillator it is necessary to force pin OSC to a DC-level above SGND for
switching from the internal to an external oscillator. In this case the internal oscillator is
disabled and the PWM will be switched on the external frequency. The frequency range of
the external oscillator must be in the range as specified in the switching characteristics;
see Section 12.1.
In an application circuit:
• Internal oscillator: ROSC connected between pin OSC and VSSA
• External oscillator: connect the oscillator signal between pins OSC and SGND; delete
ROSC and COSC
.
9397 750 13357
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Preliminary data sheet
Rev. 01 — 1 October 2004
16 of 32
NXP [ NXP ]
