ACT2861 datasheet(35/97 Pages) QORVO

35 / 97 page

Data Sheet Rev. F, April 2022 | Subject to change without notice

35 of 97

www.qorvo.com

ACT2861

30V Buck-Boost Charger with Integrated MOSFETs and OTG

Battery Charging Profile

The IC follows the standard Li-Ion battery charge profile

with four charging phases: dead battery, precondition-

ing, constant current, and constant voltage. The battery

charge current is a function the battery voltage and the

IC’s hardware and register settings. Table 3 shows

these settings.

Table 3: Charging Current Setting

VBAT

Charging

Current

Current set by

< VBATDEAD

IDBATTERY

Fixed at 10mA

VBATDEAD ~

VBATSHORT

ISHRT

I2C Configurable: 1%, 2%,

4%, 8% of IOLIM current

VBATSHORT ~

VBAT_LOW

IPRECHG

I2C Configurable: 5% to

20% of IOLIM current

> VBAT_LOW

ICHG

I2C and Hardware

Configurable

> VTERM

None

Voltage

VBAT_LOW

Battery Voltage

Charge Current

Trickle

Charge

Pre-

Charge

Fast Charge and Voltage Regulation

IPRECHARGE

ITERM

ISHRT

Dead

Battery

VBATDEAD

VTERM

IDBATTERY

IFASTCHARGE

Regulate VTERM after

charge complete

Current

VBATSHORT

Figure 10: Battery Charging Profile

Setting Charge Current

The battery charging current, ICHG, is set by a combina-

tion of a current sense resistor, an OLIM resistor, and a

scaling factor defined by I2C bits IFCHG[6:0] in register

0x18h. The maximum allowable charge current is 5A.

Figure 11 shows the hardware circuitry that sets IOLIM.

IOLIM is the maximum charge current set by hardware.

The actual battery charge current, ICHG, can be scaled

from 1% to 100% of IOLIM in 1% steps. The following

equation defines the final charge current.

ICHG=IOLIM∗IFCHG[6:0]

Where IOLIM is the hardware programmed charging cur-

rent and IFCHG[6:0] is the scaling factor. IFCHG[6:0] is

the decimal equivalent value in this register. For exam-

ple, if IOLIM, is programmed to 4A and IFCHG[6:0] =

1001011b (75% decimal), the final charge current = 4A

* 0.75 = 3A.

Note that IFCHG[6:0] is a 7 bit register and can be pro-

grammed between 0x00h and 0x7Fh (0% and 127%). If

a value of 0x00h is written to the register, the register

retains 0x00h, but the IC sets the charge current to 1%.

If a value above 0x64h (100%) is written to the register,

the IC retains the written value, but sets the charge cur-

rent to 100%.

To Battery

RCS_OUT

ROLIM

ROSRN

ROSRP

COSR

OSRN

OSRP

VBAT

OLIM

RCS_COMP

CCS_COMP

Figure 11: Charge Current Circuitry

The current sense resistor and OLIM resistor set the

IOLIM current.

��= 1000��2��

��∗��_��

Where ROLIM is the resistor from the OLIM pin to AGND

in ohms and RCS_OUT is the current sense resistor value

in ohms. The term 1000V^2/A is a constant with the

units volts^2/Ampere.

The current sense resistor, RCS_OUT, value should be

chosen to give a maximum current sense voltage be-

tween 20mV and 50mV. 50mV is the absolute maximum

allowable voltage. Using lower voltages reduces the re-

sistor’s power dissipation, but decreases accuracy. At

lower charging currents, additional RC compensation

must be placed in parallel with ROLIM. Table 4 gives rec-

ommended resistor values for different values of IOLIM

current. Contact Qorvo for compensation information if

other configurations are required.

ACT2861 Datasheet(PDF) 35 Page - Qorvo, Inc

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