Texas Instruments TPA3200D1 - Manual (Page 17)

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CLASS-D OPERATION
Traditional Class-D Modulation Scheme
0 V
−12 V
+12 V
Current
OUTP
Differential Voltage
Across Load
OUTN
TPA3200D1
SLOS442A – MAY 2005 – REVISED JULY 2005
This section focuses on the class-D operation of the TPA3200D1.
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, VCC. Therefore,
the differential pre-filtered 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 31. Note that even at an average of 0 V across the load (50% duty cycle), the current to the load is high,
causing high loss, thus causing a high supply current.
Figure 21. Traditional Class-D Modulation Scheme’s Output Voltage and Current Waveforms Into an
Inductive Load With No Input
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