STW5098 datasheet(25/86 Pages) STMICROELECTRONICS

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Functional description

STw5098

24/85

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Loudspeaker driver (one entity only): it is a monophonic differential output. It can

drive 8

Ω resistive load and deliver up to 500 mW to the load. The output gain is

regulated with LSG bits in CR7, in the range -24 to +6 dB. The input signal of the

loudspeaker driver comes from the analog mixers: bits LSSEL in CR29 select left

channel, right channel, (L+R)/2 (mono) or mute. The output common mode voltage is

obtained with an internal voltage divider from VCCLS and it is connected to CAPLS pin.

The supply voltage of the loudspeaker driver is VCCLS.

The loudspeaker driver is powered up with bit ENLS in CR2.The output pin is in high

impedance state when the loudspeaker driver is powered down.

Note:

Together with the LS driver, only a second power output is allowed among:

Ear (1EARP - 1EARN)

Headphones 1 (1HPL and 1HPR)

Headphones 2 (2HPL and 2HPR)

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Earphone driver (one entity only): it is a monophonic differential output. It can drive

Ω resistive load and deliver up to 125 mW to the load. The output gain is regulated

with EARG bits in CR7, in the range -24 to +6 dB. The input signal of the loudspeaker

driver comes from the analog mixers: bits EARSEL in CR29 select left channel, right

channel, (L+R)/2 (mono) or mute. The output Common Mode Voltage is obtained with

an internal voltage divider from VCCLS and it is connected to CAPEAR pin. The supply

voltage of the loudspeaker driver is VCCLS.

The loudspeaker driver is powered up with bit ENEAR in CR2.The output pin is in high

impedance state when the loudspeaker driver is powered down.

Note:

Note on direct connection of VCCLS to the battery:

The voltage of batteries of handheld devices during charging is usually below 5.5 V, making

VCCLS supply pin suitable for a direct connection to the battery. In this case if STw5098 is

delivering the maximum power to the load and the ambient temperature is above 70 °C then

the simultaneous charging of the battery can overheat the device. A basic protection

scheme is implemented in STw5098 (activated with bit LSLIM in CR19): it limits the

maximum gain of the loudspeaker to -6 dB when VCCLS is above 4.2 V, and it removes the

limit for VCCLS below 4.0 V. The loudspeaker gain is left unchanged if it is set below -6 dB

with bits LSG. This event (VCCLS > 4.2 V) can generate, if enabled (bit VLSMSK in CR31),

an IRQ signal.

4.11

Analog mixers

STw5098 can send to the output drivers the sum of stereo audio signals from 3 different

sources of each entity: DA path (bit MIXDAC in CR17), Microphone Preamplifiers (bit

MIXMIC in CR17) and Line In Amplifiers (bit MIXLIN in CR17). The analog mixers do not

have a gain control on the inputs, therefore the user should reduce the levels of the input

signals within the analog signal range.

The stereo analog mixers are powered up with bits ENMIXL and ENMIXR in CR2.

4.12

AD paths

In each entity the AD path converts audio signals from Microphone Preamplifiers (selected

with bit ADMIC in CR17) and Line In Amplifiers (bit ADLIN in CR17) inputs to digital domain.

If both inputs are selected then the sum of the two is converted. After AD conversion the

audio data is resampled with a sample rate converter and then processed with the internal

DSP. Two different filters are selectable in the DSP (bit ADVOICE in CR29): stereo Audio

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