AS3421 datasheet(18/61 Pages) AMSCO

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AS3421 AS3422

Datasheet - D e t a i l e d D e s c r i p t i o n

9.5 SYSTEM

The system block handles the power up and power down sequencing, as well as, the mode switching.

9.5.1

Power Up/Down Conditions

The chip powers up when one of the following conditions is true:

The chip automatically shuts off if one of the following conditions arises:

9.5.2

Start-up Sequence

The start-up sequence depends on the used mode.

In stand-alone mode the sequence runs automatically, in I2C mode(I2C MODE bit has to be pre-trimmed) the sequence runs till a defined state

and waits then for an I2C command. Either the automatic sequence is started by setting the CONT_PWRUP bit in addition to the PWR_HOLD

bit. If only the PWR_HOLD is set all enable bits for headphone, microphone, etc have to be set manually.

Figure 22. Stand-Alone Mode Start-Up Sequence

Table 8. Power UP Conditions

Source

Description

MODE_CSCL pin

In stand-alone mode, MODE pin has to be driven high to turn on the device

I2C start

In I2C mode, a I2C start condition turns on the device

Table 9. Power DOWN Conditions

Source

Description

MODE pin

Power down by driving MODE_CSCL pin to low

SERIF

Power down by SERIF writing 0h to register 20h bit <0>

Low Battery

Power down if VBAT is lower than the supervisor off-threshold

VNEG CP OVC

Power down if VNEG is higher than the VNEG off-threshold

AS3421 Datasheet(PDF) 18 Page - ams AG