User's Manual

T-0000-0004-V2.1: Using Mozart II
T-0000-0004-V2.1: Using Mozart II Page: 4 / 24
4.4 AUDIO SECTION
4.4.1 LINE OUT
The module has a Line Out stereo connection. The lines are DC coupled with a 1.35V offset and a
0.7Vpp modulation range. Depending on the software configuration, the modulation level can be fixed
or may follow user volume settings.
4.4.2 FM OUT
The analog outputs of the FM tuner are available to provide flexibility for out-of-module analog paths.
The normal way to use them is to link to Line_In pins; if an external multiplexer has to be used, then
the SELECT signal can be used to distinguish between FM and external source.
4.4.3 LINE IN
The module has a Line In stereo connection. The line
s are DC coupled and will accept a 0.7Vpp
modulation range. Depending on the software configuration, the input level can be fixed or may follow
user settings. Input impedance is 47kOhms.
4.4.4 HP OUT
The module has a Headphones amplified stereo connection. The lines are DC coupled with a 1.35V
offset and will drive 16 Ohm headphones at up to 30 mW and 32 Ohm headphones at up to 15 mW.
4.5 VOLUME CONTROL STRATEGIES
The module features two audio outputs; one is a line-level output and one is a headphones output.
Both can be controlled by software independently, however the way to use them depends on the
global design of the target product and the envisioned use cases.
The headphones output is capable of driving standard 32 Ohm headphones at up to 15 mW output
power. It is up to the customer to decide whether this is enough or not; if not external amplification
must be used.
If headphones plug need to be added, there are two solutions:
• Use the module headphones output. In this case, if internal speaker cut-off is required, it must
be implemented in relationship with the amplifier.
• Use the amplifier output to drive the headphones.
When simultaneous speakers and line out is required, in most cases the volume of the line outputs will
not vary. In this case, the only solution is to use the headphones output to feed the internal amplifier
(with jack before or after amplifier), and to connect the line outputs directly to the line out connector.
The module has a STANDBY and a MUTE signal. The MUTE signal will be active as soon as the
module is not producing audio signals. The STANDBY signal needs to control powering of the
amplifier, while the MUTE signal can be used to make sure audio outputs from the module will be
turned down. It is important to note that at initialization time, the audio output of the module can
produce spurious sounds – this is why the external logic must take care of not amplifying them.
In case of required mono internal speaker, the internal amplifier will be monophonic as well and will be
fed with a mix of the left and right signals. In this case, it will not be possible to have a design on which
the heapdhones jack will be connected to the internal amplifier – the only way to have stereo output is
to use the amplified outputs of the module.