STW5095_07 Datasheet, PDF (18/73 Pages) STMicroelectronics – Low-power asynchronous stereo audio Codec with integrated power amplifiers

STw5095
Functional description
18 bit to 32 bit data word.
The SPI interface can be configured as a single-channel (mono) interface with bit SPIM
(ADSPIM and DASPIM). The mono interface always exchanges the left channel
sample.
SPI-Format can only be Slave: if Master Mode is selected the CK and SYNC pins are
set to 0. Bit CKP (ADCKP and DACKP) affects the interface format inverting the polarity
of CK pin.
● PCM-Format (DAFORM or ADFORM =111): this format is monophonic, as it can only
receive (DA) and transmit (AD) single channel data (Figure 10 on page 48). It is mainly
used when voice filters are selected. If audio filters are used then the same sample is
sent from DA-PCM interface to both channel of DA path, and the left channel sample
from AD path is sent to AD-PCM interface. If in the AD path the right channel has to be
sent to the PCM interface then the following must be set: ADRTOL=1 (CR27) and
ENADCL=0 (CR1). In Master Mode the number of CK periods per SYNC period is
between 16 and 512 (see DAPCMF in CR22 and ADPCMF in CR25, Section 5.6 on
page 34 for details). Bit CKP (ADCKP and DACKP) affects the interface format
inverting the polarity of CK pin. Bit SYNCP (ADSYNCP and DASYNCP) switches
between delayed (SYNCP=0) and non delayed (SYNCP=1) formats.
4.8
Analog inputs
STw5095 has a stereo Microphone preamplifier and a stereo Line In amplifier, with inputs
selectable among 5: MIC (for Microphone preamplifier only), LINEIN (for Line In amplifier
only) and 3 different AUX inputs (for Microphone and Line In amplifiers). The AUX inputs can
be used simultaneously for Line In amplifiers and Microphone preamplifiers.
● Microphone preamplifier: it has a very low noise input, specifically designed for low
amplitude signals. For this reason it has a high input gain (up to 39 dB) keeping a
constant 50 kΩ input impedance for the whole gain range. However it can also be used
as a line in preamplifier because it can accept a high dynamic input signal (up to 4 V_pp).
There are two separate gain and attenuation stages in order to improve the S/N ratio
when the preamplifier output range is below full scale (volume control).The gain and
attenuation controls are separate for left and right channel (CR3 and CR4 respectively).
The Preamplifier input is selected with bits MICSEL in CR18, and it is disconnected
when MICMUTE=1. If a single ended input is selected then the preamplifier uses the
selected pin as the positive input and connects the negative input (for both left and right
channels) to CAPMIC pin, which has to be connected through a capacitor to a low
noise ground (typically the same reference ground of the input).
The stereo Microphone preamplifier is powered up with bits ENMICL and ENMICR in
CR1.
● Line In amplifier: it is designed for high level input signal. The input gain is in the range
-20 dB up to 18 dB. The Line In amplifier input is selected with bits LINSEL in CR18,
and it is disconnected when LINMUTE=1. If a single ended input is selected then the
amplifier uses the selected pin as the positive input and connects the negative input (for
both left and right channels) to CAPLINEIN pin, which has to be connected through a
capacitor to a low noise ground (typically the same reference ground of the input).
The stereo Line In amplifier is powered up with bits ENLINL and ENLINR in CR1.
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