STW5095T datasheet(16/69 Pages) STMICROELECTRONICS

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3 Functional Description

STw5095

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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.

3.9

Analog output drivers

STw5095 provides 3 different analog signal outputs and 1 common mode reference output:

●

Line Out Drivers: it is a stereo differential output, it can be used as single-ended output

just by using the positive or negative pin. It can drive 1 k

Ω resistive load. The load can be

connected between the positive and negative pins or between one pin and ground through

a decoupling capacitor. The output gain is regulated with LOG bits in CR7, in the range 0

to -18 dB, simultaneously for left and right channels. When used as a single ended output

the effective gain is 6 dB lower. It is muted with bit MUTELO in CR19. The input signal of

this stereo output can come from the analog mixer or directly from MIC preamplifiers. The

output Common Mode Voltage level is controlled with bits VCML in CR19. The supply

voltage of line out drivers is VCCP.

The Line Out Drivers are powered up with bits ENLOL and ENLOR in CR1. The output

pins are in high impedance state with a 180k

Ω pull-down resistor when the Line Out

Drivers are powered down.

●

Headphones Drivers: it is a stereo single ended output. It can drive 16 Ohm resistive load

and deliver up to 40 mW. The output gain is regulated with HPLG and HPRG bits in CR8

and CR9 respectively, with a range of -40 to 6 dB. It is muted with bit MUTEHP in CR19.

The input signal of this stereo output comes from the analog mixer.The output Common

Mode Voltage is controlled with bits VCML in CR19. The supply voltage of headphones

drivers is VCCP.

The Headphones Drivers are powered up with bits ENHPL and ENHPR in CR2.The output

pins are in high impedance state when the Headphones Drivers are powered down.

●

Common Mode Voltage Driver: it is a single ended output with output voltage value

selectable with bits VCML in CR19, from 1.2 V to 1.65 V in steps of 150 mV. The output

voltage should be set to the value closest to VCCP/2 to optimize output drivers

performance. The Common Mode Voltage Driver is designed to be connected to the

common pin of stereo headphones, so that decoupling capacitors are not needed at HPL

and HPR outputs. The supply voltage of the common mode voltage driver is VCCP.

The Common Mode Voltage Driver is powered up with bit ENHPVCM in CR2.The output

pin is in high impedance state when the Common Mode Voltage Driver is powered down.

●

Loudspeaker Driver: 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:

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 STw5095 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 STw5095 (activated with bit LSLIM in CR19): it limits the maximum gain of the

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