TDA7491MV View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TDA7491MV' PDF : 28 Pages View PDF
TDA7491MV
Application information
7.5
Filterless modulation
The output modulation scheme of the BTL is called unipolar pulse width modulation (PWM).
The differential output voltages change between 0 V and +VCC and between 0 V and -VCC.
This is in contrast to the traditional bipolar PWM outputs which change between +VCC
and -VCC.
An advantage of this scheme is that it effectively doubles the switching frequency of the
differential output waveform. The OUTP and OUTN are in the same phase when the input is
zero, then the switching current is low and the loss in the load is small. In practice, a short
delay is introduced between these two outputs in order to avoid the BTL output switching at
the same time.
TDA7491MV can be used without a filter before the speaker, because the frequency of the
TDA7491MV output is beyond the audio frequency, the audio signal can be recovered by
the inherent inductance of the speaker and natural filter of the human ear.
Figure 23. Unipolar PWM output
INP
INN
OUTP
OUTN
Differential
OUT
DocID14576 Rev 4
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