Datasheet

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TRADITIONAL CLASS-D MODULATION SCHEME
0 V
−5 V
+5 V
Current
OUTP
Differential Voltage
Across Load
OUTN
TPA2008D2
SLOS413C – JULY 2003 – REVISED MAY 2004
APPLICATION INFORMATION (continued)
The traditional class-D modulation scheme, which is used in the TPA032D0x family, has a differential output
where each output is 180 degrees out of phase and changes from ground to the supply voltage, V
CC
. Therefore,
the differential prefiltered output varies between positive and negative V
CC
, where filtered 50% duty cycle yields 0
V across the load. The traditional class-D modulation scheme with voltage and current waveforms is shown in
Figure 14 . Note that even at an average of 0 V across the load (50% duty cycle), the current to the load is high,
resulting in a high I
2
R loss, thus causing a high supply current.
Figure 14. Traditional Class-D Modulation Scheme's Output Voltage and Current Waveforms Into an
Inductive Load With No Input
12