ADP5350ACBZ-1-R7 datasheet(23/63 Pages) AD

23 / 63 page

Data Sheet

ADP5350

Rev. B | Page 23 of 63

Table 11. Input Current Compatibility with Standard USB Limits

Mode

Standard USB Limit

ADP5350 Function

USB 2.0

100 mA limit for standard USB host or hub

100 mA input current limit or I2C programmed value

500 mA limit for standard USB host or hub

500 mA input current limit or I2C programmed value

USB 3.0

150 mA limit for super speed USB 3.0 host or hub

150 mA input current limit or I2C programmed value

900 mA limit for super speed, high speed USB host or hub

charger

900 mA input current limit or I2C programmed value

Dedicated Charger

1500 mA limit for dedicated charger or low/full speed USB

host or hub charger

1500 mA input current limit or I2C programmed value

Watchdog Timer

The ADP5350 charger features a programmable watchdog timer

function to ensure charging is under the control of the processor.

The watchdog timer starts running when the ADP5350 charger

determines that the processor is operational, that is, when the

processor sets the RESET_WD bit for the first time or when the

battery voltage is greater than the weak battery threshold,

VWEAK. When the watchdog timer triggers, it must be reset

regularly within the watchdog timer period, tWD.

If the watchdog timer expires without being reset while in

charger mode, the ADP5350 charger assumes there is a software

problem and triggers the safety timer, tSAFE. For more infor-

mation, see the Safety Timer section. Meanwhile, the ILIM

current limit resets to the default value.

Safety Timer

If the watchdog timer (see the Watchdog Timer section for

more information) expires while in charger mode, the ADP5350

charger initiates the safety timer, tSAFE. Charging continues for a

period of tSAFE, and then stops. The battery isolation FET remains

on while the dc-to-dc regulator shuts down. The CHARGER_

STATUS[3:0] bits are then set. Resetting the charger requires

VBUSx to be powered down and powered up.

Charge Complete

The ADP5350 charger monitors the charging current while in

CV fast charge mode. If the current falls below IEND and remains

below IEND for tEND, the charger is stopped by turning the battery

isolation FET off, but the system voltage is maintained at VISOS_TRK

by the dc-to-dc regulator and the CHDONE flag is set. If the

charging current falls below IEND for less than tEND and then rises

above IEND again, the tEND timer resets.

Recharge

After the detection of a complete charge, and the isolated FET

turns off, the ADP5350 charger continues to monitor the BSNS

pin. If the BSNS pin voltage falls below VTRM − VRCH, the charger

reactivates charging. Under most circumstances, triggering the

recharge threshold results in the charger entering fast charge

constant current mode.

Battery Charging Enable/Disable

The ADP5350 charging function can be disabled by setting the

I2C EN_CHG bit to low. If the I2C EN_CHG bit is low, the

dc-to-dc regulator is still on and regulates the ISOS voltage to

VISOS_TRK, the battery isolation FET turns off, and the dc-to-dc

regulator provides the power for the system.

BATTERY ISOLATION FET

The ADP5350 charger features an integrated battery isolation

FET for power path control. The battery isolation FET isolates a

deeply discharged Li-Ion cell from the system power supply in

trickle charge mode and when charging is complete, thereby

allowing the system to be powered from the VBUSx node.

When the VVBUSx voltage is below VVBUSOK_FALL, the battery

isolation FET is in full conduction mode.

The battery isolation FET is off during trickle charge mode.

When the battery voltage exceeds VTRK_DEAD, the battery

isolation FET switches to the system voltage regulation mode

and the battery isolation FET maintains the VISOS_FC voltage on

the ISOS pin. When the battery voltage exceeds VISOS_FC, the

battery isolation FET is in full conduction mode.

The battery isolation FET supplements the battery to support

high current functions on the system power supply.

When the voltage on ISOS drops below ISOB, the battery

isolation FET enters full conduction mode.

When the voltage on ISOS rises above ISOB, the isolation FET

enters regulating mode or full conduction mode, depending on the

Li-Ion cell voltage and the dc-to-dc charger mode.

BATTERY DETECTION

Battery Level Detection

The ADP5350 charger features a battery detection mechanism to

detect an absent battery. The charger actively sinks and sources

current into the ISOB/BSNS node when the enable charger and

VVBUSx have reached the VVBUSOK_RISE level, and voltage vs. time is

detected. The sink phase is used to detect a charged battery,

whereas the source phase is used to detect a discharged battery.

The sink phase (see Figure 41) sinks ISINK current from the ISOB

and BSNS pin for a time, tBATOK. If the BSNS pin is below VBATL

when the tBATOK timer expires, the charger assumes no battery is

present or battery is shorted, and starts the source phase. If the

BSNS exceeds the VBATL voltage when the tBATOK timer expires,

the charger assumes the battery is present and begins a new

charge cycle.

The source phase sources ISOURCE current to ISOB or the BSNS

pin for a time, tBATOK. If the BSNS pin exceeds VBATH before the

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