AS3412 datasheet(37/84 Pages) AMSCO

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ams Datasheet

Page 37

[v1-00] 2016-Apr-06

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AS3412 − Detailed Description

Playback Only Mode

The active noise cancelling feature of the AS3412 can also be

disabled with the ANC/CSDA pin. The ANC/CSDA pin has to be

pulled high to enable the ANC function during startup (ANC

MODE). If the pin is connected to ground, the chip enters

playback only mode (PBO MODE) in which the ANC function is

disabled. The operating mode of the line input mute switch, as

well as the mixer input, can be defined in register PBO_MODE.

The microphone amplifier shuts down automatically, but it is

possible to control the operational amplifiers in this mode

separately. Typically only the line input amplifiers and the

headphone amplifier are enabled in the playback only mode. If

this function is not desired you just need to pull the pin high

through a 22kΩ resistor.

Figure 49:

Playback Only Mode Timing Diagram

Playback Only Mode Timing Diagram: The diagram shows the necessary voltages and timings for different

operation modes in Playback Only Mode.

ANC/CSDA Pin

ANC ON

Playback Only Mode

ANC ON

200-400ms

>65% VBAT

<35% VBAT

Operation Mode

AS3412 Datasheet(PDF) 37 Page - ams AG