Datasheet

V
(rms)
+
V
O(PP)
2 2
Ǹ
Power +
V
(rms)
2
R
L
(4)
f
c
+
1
2pR
L
C
C
(5)
R
L
2x V
O(PP)
V
O(PP)
–V
O(PP)
V
DD
V
DD
R
L
C
C
V
O(PP)
V
O(PP)
V
DD
–3 dB
f
c
TPA6203A1
SLOS364F – MARCH 2002 – REVISED JUNE 2008 .......................................................................................................................................................... www.ti.com
low-frequency performance of the system. This
frequency-limiting effect is due to the high pass filter
network created with the speaker impedance and the
coupling capacitance and is calculated with
Equation 5 .
For example, a 68- µ F capacitor with an 8- Ω speaker
would attenuate low frequencies below 293 Hz. The
BTL configuration cancels the dc offsets, which
eliminates the need for the blocking capacitors.
Low-frequency performance is then limited only by
the input network and speaker response. Cost and
PCB space are also minimized by eliminating the
bulky coupling capacitor.
Figure 31. Differential Output Configuration
In a typical wireless handset operating at 3.6 V,
bridging raises the power into an 8- Ω speaker from a
singled-ended (SE, ground reference) limit of 200
mW to 800 mW. In sound power that is a 6-dB
improvement — which is loudness that can be heard.
In addition to increased power there are frequency
response concerns. Consider the single-supply SE
configuration shown in Figure 32 . A coupling
capacitor is required to block the dc offset voltage
Figure 32. Single-Ended Output and Frequency
from reaching the load. This capacitor can be quite
Response
large (approximately 33 µ F to 1000 µ F) so it tends to
be expensive, heavy, occupy valuable PCB area, and
Increasing power to the load does carry a penalty of
have the additional drawback of limiting
increased internal power dissipation. The increased
dissipation is understandable considering that the
BTL configuration produces 4 × the output power of
the SE configuration.
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