AS3658 datasheet(120/158 Pages) AMSCO

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AS3658

Data Sheet Confidential - Deta il ed Descri ption - System Functi ons

Voltage detection:

There are two types of voltage dependent resets: VPOR and VXRESET. VPOR monitors the voltage on V2_5 and

VXRESET monitors the voltage on VSUPPLY. The linear regulator for V2_5 is always on and uses the voltage

VCHARGER, VBAT or V_USB as its source.

The pin RESET is only released if V2_5 is above VPOR and VSUPPLY is above VXRESETRISE.

Table 124. Reset Levels

Symbol

Parameter

Min

Typ

Max

Unit

Note

VRESETFALLING is only accepted if the reset condition is longer than VRESETMASK. This guard time is used to avoid a

complete reset of the system in case of short drops of VBAT.

Power off:

To put the chip into ultra low power mode, write ‘1’ into xon_enable and ‘1’ into power_off. The chip stays in power off

mode until the external pin XON is pulled low, the charger is inserted or the level VPOR 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 AS3658 is reduced to less than 15 µA. 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.

Software forced reset

Writing ‘1’ into the register bit force_reset immediately starts a reset cycle. The bit force_reset is automatically cleared

by this reset.

External triggered reset:

If the pin XRESET is pulled from high to low by an external source (e.g. microprocessor or button) a reset cycle is

started as well.

Overtemperature reset:

The reset cycle can be started by overtemperature conditions. (see Protection Functions on page 134)

Watchdog reset:

If the watchdog is armed (register bit wtdg_on = 1 and wtdg_res_on = 1) and the timer expires it causes a reset. (see

Watchdog on page 135).

VPOR

Overall power on reset

1.5

2.0

2.3

Monitor voltage on V2_5; power on

reset for all internal functions

VXRESETRISE

Reset level for Vsupply

rising

ResVol

trise

Monitor voltage on Vsupply; rising

level

VXRESETFALLING

Reset level for Vsupply

falling

2.7

Monitor voltage on VSupply; falling

level

ResVol

tfall

if SupResEn=1 only

VRESETMASK

Mask time for

VXRESETFALLING

2.0

2.5

3.0

Duration for VBAT<VXRESETFALLING

until a reset cycle is started

1. VRESET signal is debounced with the specified mask time for rising- and falling slope of VBAT.

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