AS3415 datasheet(54/102 Pages) AMSCO

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AS3415/AS3435 – 54

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

De tail ed De sc rip t ion

OTP Fuse Storing

Many wireless applications, like Bluetooth single chips support

programmable solutions, as well as ROM versions. As such, it is

necessary for ROM versions to store microphone gain

compensation data and the general ANC configuration inside

the ANC chip. This is necessary because there is no other way

to configure the ANC chip during startup. In order to guarantee

successful trimming of AS3415/35 it is necessary to provide a

decent environment for the trimming process. Figure 69 shows

a principal block diagram for trimming the AS3415/35 properly

in production using the I²C interface. The most important block

is the external power supply. Usually it is possible to trim the

AS3415/35 with a single supply voltage of min. 1.8V in

laboratory environment, but as soon as it comes to mass

production we highly recommend buffering VNEG supply of the

chip. As highlighted in the block diagram, it is mandatory to get

a voltage difference between VPOS and VNEG of 3.4V (minimum)

to guarantee proper trimming of the device, therefore it is

possible to buffer it externally with a negative power supply.

The VNEG voltage applied to VNEG pin must be lower than the

voltage created with the charge pump. This means if the typical

VNEG output voltage is -1.5V you can easily apply externally

-1.7V. The charge pump switches then automatically into skip

mode.

Figure 69:

Production Environment I²C Interface Trimming

I²C Trimming: This block diagram shows a general overview of the production environment when storing the

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