ADP5360ACBZ-2-R7 datasheet(20/60 Pages) AD

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ADP5360

Data Sheet

Rev. 0 | Page 20 of 60

THEORY OF OPERATION

BATTERY CHARGER

Charger Introduction

The ADP5360 integrates a fully I2C-programmable charger for

single-cell Li-Ion/Li-Poly batteries suitable for a wide range of

portable applications.

The linear charger architecture enables up to 500 mA of output

current on the system power supply and up to 320 mA of charge

current into the battery from a dedicated charger.

The charger of the ADP5360 operates from an input voltage of

up to 6.8 V but is tolerant of voltages up to 20 V to alleviate the

concern of USB bus spiking during disconnection or connection

scenarios.

The ADP5360 features an internal FET between the linear

charger output and the battery node to permit battery isolation

and system power in a dead battery or no battery scenario,

allowing instanteneous system function when connected to a

USB power supply.

The charger of theADP5360 enables charging via the mini

VBUS pin (F6 pin) from a wall charger, car charger, or USB host

port. Based on the type of USB source, which is detected by an

external USB detection device, theADP5360 can apply the proper

current limit for optimal charging and USB compliance. The USB

charger permits correct operation under all USB compliant

sources including wall chargers, host chargers, hub chargers, and

standard hosts and hubs.

A processor controls the USB charger using the I2C to program

the charging current and numerous other parameters, including

the following:

•

Trickle charge current level and voltage threshold

•

Fast charge (constant current) current level

•

Fast charge (constant voltage) termination voltage level

•

Fast charge safety timer period

•

Weak battery threshold detection

•

End of charge current level for charge completion

•

Recharge voltage threshold

•

VBUS input current limit

Input Current Limit and USB Compatibility

The VBUS input current limit is programmed via an internal

I2C ILIM register (RILIM) from 50 mA to 500 mA, ensuring

compatibility with different requirements. An external resistor

from the ILIM pin to ground can also set the input current limit

as the default. Floating the ILIM pin activates the register

default value when powering up.

Table 10. VBUS Input Current-Limit Default Set with ILIM Pin

RILIM Value (kΩ)

ILIM Value (mA)

100

150

200

250

300

400

500

The current-limit defaults to 100 mA to allow compatibility

with a USB host or hub that is not configured. This input

current limit resets to a default value of 100 mA during every

VBUS power-on cycle, thereby protecting the USB port.

When the input current-limit feature is used, it is possible for

the available input current to be too low for the charger to meet

the programmed charging current (ICHG), and the rate of charge

reduces. In this case, the VBUS_ILIM bit flag sets.

When VVBUS is between 3.9 V and 6.8 V, the VBUSOK bit is set.

Trickle Charge Mode

A deeply discharged Li-Ion cell can exhibit a low cell voltage,

making it unsafe to charge the cell at high current rates. The

ADP5360 charger uses its trickle charge mode to raise the cell

voltage to a safe level for fast charging.A cell with a voltage lower

than VTRK_DEAD charges with ITRK_DEAD. During trickle charge mode,

the CHARGER_STATUS[2:0] bits of the CHARGER_STATUS1

During trickle charging, the VSYS node is regulated to VSYS_REG

by the linear regulator. The battery isolation FET is off, therefore

the battery is isolated from the system power supply. Refer to

Table 11 for the VSYS_REG output voltages.

Table 11. VSYS_REG Output Voltages

VTRM Setting

VSYS_REG (V)

VSYSTEM =VTRM + 200 mV

VSYSTEM = 5 V

VTRM ≤ 4.26 V

4.4

4.26 V < VTRM ≤ 4.36 V

4.5

4.36 V < VTRM ≤ 4.46 V

4.6

4.46 V < VTRM ≤ 4.56 V

4.7

4.56 V < VTRM ≤ 4.66 V

4.8

When VVBUS is lower than the set value of VSYS_REG, VVSYS cannot

be regulated, which impacts the charged current (see Figure 9).

ADP5360ACBZ-2-R7 Datasheet(PDF) 20 Page - Analog Devices

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