AS3658F-BCTP datasheet(113/158 Pages) AMSCO

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AS3658

Data Sheet Confidential - Detail ed Descri ption- Audio Functi ons

Left Line Register

Table 117. LINE_OUT_L Register

Addr:84

LINE_OUT_L

These bits control the Line in volume and mode

Bit

Bit Name

Default

Access

Description

9.11

Headphone Output

The headphone output is designed to provide the audio signal with 2x40mW @ 16

Ω or 2x20mW @32Ω, which are

typical values for headphones.

This output stage has an independent gain regulation for left and right channel with 32 steps @ 1.5dB each. The gain

can be set from –40.5dB to +6dB.

9.11.1 Phantom Ground

HP_CM_PWR pin is the buffered HP_CM output. It can be used to drive the common mode level with a load of 2k

Ω.

The phantom ground can be switched off to save power if not needed.

9.11.2 No-Pop Function

To avoiding click and pop noise during power-up and shutdown, the output is automatically set to mute when the output

stage is disabled. Also the volume settings are set to their default values, and can’t be changed, as long the output

stage is not enabled.

HP_CM pin, which needs a 100nF to 1µF capacitor outside, gets charged on power-up with 1µA to AVDD/2. After start-

up the DC level of the following pins are the same: HPR=HPL=HP_CM=HP_CM_PWR=AVDD/2. The Start-up time

before releasing mute is about 150ms. To avoid pop-noise 150ms discharging time of HP_CM after a shutdown, have

to be waited before starting up again.

9.11.3 Over-current Protection

This output stage has an over-current protection, which disables the output for 256ms or 512ms. This value can be set

in the headphone registers. The over-current protection limit of HPR and HPL pin is about 260mA while HP_CM_PWR

pin has a 370mA limit.

4:0

liner_vol

00000b

R/W

volume settings for left Line output, adjustable in 32

steps @ 1.5dB

00000

-40.5 dB gain

00001

-39 dB gain

......

11110

4.5 dB gain

11111

6 dB gain

reserved

line_on

R/W

Line stage not powered

power up Line stage

line_mute

R/W

normal operation

Line output set to mute (mute is on during

power-up)

AS3658F-BCTP Datasheet(PDF) 113 Page - ams AG

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