AS3709 datasheet(26/74 Pages) AMSCO

26 / 74 page

AS3709 – 26

ams Datasheet, Confidential: 2013-Aug [1-02]

Det a il e d De sc r i pt ion - S y s t em F u nc t i on s

Reset

XRES is a low active bi-directional pin. An external pull-up to

the periphery supply has to be added. During each reset cycle

the following states are controlled by the AS3709:

• Pin XRES is forced to GND

• Normal startup with programmable power-on sequence

and regulator voltages

• Reset is active until the programmable reset timer (set by

• All registers are set to their default values after power-on,

except the reset control- and status-registers

RESET Reasons

Reset can be activated from 7 different sources:

•VPOR has been reached (VSUP reached POR level)

• ResVoltFall was reached (VSUP drops below ResVoltFall)

• Software forced reset

• Power off mode

• External triggered through the pin XRES

• Over-temperature

•ON-key long press

Voltage Detection

There are two types of voltage dependent resets: VPOR and

VXRES. VPOR monitors the voltage on V2_5 and VXRES monitors

the voltage on VSUP. The linear regulator for V2_5 is always on

and uses the voltage VSUP as its source. The pin XRES is only

released if V2_5 is above VPOR and VSUP is above ResVoltRise.

Power OFF

To put the chip into ultralow power mode, write ‘1’ into

power_off.

The chip stays in power off mode until

• The external pin ON is pulled high

•The VPOR level is touched to start a complete reset cycle

The bit power_off is automatically cleared by this reset cycle.

During power_off state all circuits are shut-off except the Low

Power LDO (V2_5). Thus the current consumption of AS3709 is

reduced to less than 7μA. The digital part is supplied by V2_5,

all other circuits are turned off in this mode, including

references and oscillator. Except the reset control registers, all

other registers are set to their default value after power-on.

AS3709 Datasheet(PDF) 26 Page - ams AG