Datasheet

0V
-12V
+12V
Current
OUTP
OUTN
Differential
Voltage
Across
Load
0V
-12V
+12V
Current
OUTP
OUTN
Differential
Voltage
Across
Load
Output=0V
Output>0V
TPA3111D1
SLOS618E –AUGUST 2009–REVISED AUGUST 2012 www.ti.com
CLASS-D OPERATION
This section focuses on the class-D operation of the TPA3111D1.
TPA3111D1 Modulation Scheme
The TPA3111D1 uses a modulation scheme that allows operation without the classic LC reconstruction filter
when the amp is driving an inductive load. Each output is switching from 0 volts to the supply voltage. The OUTP
and OUTN are in phase with each other with no input so that there is little or no current in the speaker. 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 most of the switching period, greatly reducing the switching current, which reduces any I
2
R
losses in the load.
Figure 18. The TPA3111D1 Output Voltage and Current Waveforms Into an Inductive Load
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