TFA9812HN PHILIPS [NXP Semiconductors], TFA9812HN Datasheet - Page 21

• Manufacturer Part Number: TFA9812HN
• Description: BTL stereo Class-D audio amplifier with I2S input
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
TFA9812_2
Preliminary data sheet
8.5.3 Soft mute and mute
8.5.4 Output signal and word-select polarity control
8.5.5 Gain boost and clip level control
Table 16.
Section 9
In Legacy mode the pin AVOL (32) can be used to control the volume.
Voltage levels of 0.8 V to 2.8 V correspond linearly to control values of 00h (0 dB) to F9h
(mute). See
An external pull-up resistor connected to the V
volume of 0 dB. Pin AVOL has no function in I
Soft mute is available in I
in I
In I
channels to mute level over a duration of 128/f
implemented as a raised cosine function. Soft demute results in a similar gain increase.
This implementation avoids audible plops.
A different soft mute and soft demute function is implemented in Legacy mode. This works
via the analog gain control under the control of pin AVOL. The analog volume control input
signal is first-order low-pass filtered with a time constant of 10 ms in the digital domain.
Suddenly switching on or switching off volume by setting the control voltage to
> 2.8 V or < 0.8 V respectively will result in a fading which lasts approximately 15 ms
(switching between 0 V and 3.3 V at AVOL).
In Legacy mode the soft demute function that is part of the automatic power-up sequence
is similar to the I
soft and hard mute functions can be found In
In I
effect is a 180 degree phase shift of both output signals.
The TFA9812 also has the option of switching the polarity of the WS signal. Without
polarity inversion the left audio signal is connected to channel 1 and the right audio signal
is connected to channel 2.
The I
An additional gain boost of +24 dB can be selected in the TFA9812. In Legacy mode this
feature can be selected with the GAIN pin, see
[7:0] control value (hexadecimal)
00
01
...
F7
F8
F9
2
2
2
C control mode.
C control mode the soft mute function smoothly reduces the gain setting for both
C control mode the TFA9812 can switch the polarity of the stereo output signal. The
2
C control for the polarity switch can be found in
shows the I
Volume control channel suppression table
Table
2
C mode soft demute function described above. The I
16.
2
Rev. 02 — 22 January 2009
C address locations for the digital gain control for both channels.
2
C and in Legacy control modes: hard mute can be enabled only
BTL stereo Class-D audio amplifier with I
Gain (dB)
0
steps of 0.5 dB
mute
Section
2
DDD(3V3)
0.5
123.5
124
s
C mode.
Table
seconds. The smooth shape is
17.
9.
Section
can be applied to provide a default
9.5.1.
2
C control for the
© NXP B.V. 2009. All rights reserved.
TFA9812
2
S input
21 of 66