AS3701 datasheet(26/110 Pages) AMSOSRAM

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[v1-11] 2016-Dec-14

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AS3701 − Detailed Description – Power Management Functions

Charging Cycle Description

Charge Adapter Detection

The charge controller uses an integrated detection circuit to

determine if an external charge adapter has been applied to

the VUSB pin. If the adapter voltage exceeds the battery voltage

at pin VBAT by VCHDET the ChDet [ChargerStatus2] will be set.

The detection circuit will reset the charge controller (bit ChDet

is cleared) as soon as the voltage at the VUSB pin drops to only

VCHMIN above the battery voltage. In case the AS3701 device is

reset the charge controller will also be reset, even if a charge

adapter is applied to the VUSB pin. The Charger detection can

be disabled by setting the bit chdet_off [ChargerStatus2] to “1”,

which results in a further decrease of internal power

consumption.

Low Current (Trickle) Charging

Trickle charge mode is started when an external charge adapter

has been detected, the bit bat_charging_enable

[ChargerControl] is set and the battery voltage at pin VBAT is

below the VTRICKLE threshold; bits ChDet and Trickle

[ChargerStatus1] will be set. In this mode the charge current will

be limited to TrickleCurrent [ChargerCurrentControl] to prevent

undue stress in case of deeply discharged batteries. Once

VTRICKLE has been exceeded, the charger will change over to

constant current charging (Trickle is cleared).

Constant Current Charging

Constant current charging is initiated when bat_charging_

enable [ChargerControl] and the battery voltage at pin VBAT is

above the VTRICKLE and below VCHOFF. The bit CCM

[ChargerStatus1] is set when the charger has started, and the

charge current will be limited by the battery charge controller.

The current for the Constant Current Charging can be selected

out of the range defined in ConstantCurrent

[ChargerCurrentControl] if the bit cc_range_select

[ChargerControl] is set to “0” or out of the range defined in

TrickleCurrent [ChargerCurrentControl] if the bit cc_range_select

[ChargerControl] is set to “1”. When the battery approaches full

charge, its voltage will reach the charge termination threshold

VCHOFF. VCHOFF depends on the ChVoltEOC

[ChargerVoltageControl] bits settings. Top-OFF charge will be

started and the bit CVM [ChargerStatus1] will be set.

Constant Voltage Charging

Constant voltage charge mode is initiated and the bit CVM

[ChargerStatus1] will be set when the VCHOFF threshold has been

reached. The charge current is monitored during constant

voltage charging. It will be decreasing from its initial value

during constant current charging and eventually drops below

5% or 50% of the Constant Current value (depends on the

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