STW5095T datasheet(18/73 Pages) STMICROELECTRONICS

18 / 73 page

STw5095

Functional description

17/72

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.

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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 k

Ω 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 Vpp).

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.

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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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