TPA3003D2

SLOS406A − FEBRUARY 2003 − REVISED MARCH 2003

15

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APPLICATION INFORMATION

class-D operation

This section focuses on the class-D operation of the TPA3003D2.

traditional class-D modulation scheme

The traditional class-D modulation scheme, which is used in the TPA032D0x family, has a differential output

0 V across the load. The traditional class-D modulation scheme with voltage and current waveforms is shown

in Figure 22. 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.

0 V

−12 V

+12 V

Current

OUTP

Differential Voltage

Across Load

OUTN

Figure 22. Traditional Class-D Modulation Scheme’s Output Voltage and

Current Waveforms Into an Inductive Load With No Input

TPA3003D2 modulation scheme

The TPA3003D2 uses a modulation scheme that still has each output switching from 0 to the supply voltage.

However, OUTP and OUTN are now in phase with each other with no input. The duty cycle of OUTP is greater

than 50% and OUTN is less than 50% for positive output voltages. The duty cycle of OUTP is less than 50%

and OUTN is greater than 50% for negative output voltages. The voltage across the load sits at 0 V throughout