AS3435 datasheet(27/102 Pages) AMSCO

27 / 102 page

ams Datasheet, Confidential: 2014-Jun-13 [v1-30]

AS3415/AS3435 – 27

Detaile d Desc rip t ion

Microphone Supply

The AS3415/35 features an integrated microphone supply

charge pump. This charge pump provides the proper

microphone supply voltage for a single cell battery supply

(1.5V). Since AAA batteries can operate down to 1.0V, the direct

battery voltage cannot be used for microphone supply. This

would reduce the sensitivity of the microphone dramatically.

Figure 27:

Microphone Supply

Microphone Supply: This block diagram shows how the integrated microphone supply works including all

options for configuration like off mode and bypass mode.

Therefore the integrated charge pump generates a microphone

supply voltage which is typically 2.7V. In case the ANC chipset

is supplied with a fixed voltage e.g. 1.8V the integrated charge

pump supports a mode which allows the designer to directly

connect the microphone supply pin to the chip supply voltage.

This can help to reduce total power consumption of the system.

A third mode is available to switch off the microphone supply.

This use case can occur if the headset is operated without ANC

function. Please mind that you must not switch off the

microphone supply at all if the integrated music bypass

function is in use. The microphone supply voltage is also used

to switch off the integrated music bypass switch if the

AS3415/35 is in active mode.

Bypass Switch Operation:

When using the integrated music bypass

switch you must not switch off the

microphone supply!

AS3435 Datasheet(PDF) 27 Page - ams AG