ACT81460 datasheet(48/60 Pages) ACTIVE-SEMI

48 / 60 page

ACT81460

Rev 1.0, 18-Dec-2018

Innovative PowerTM

www.active-semi.com

ActiveSwitcherTM is a trademark of Active-Semi

ACTIVE PATH LINEAR CHARGER

(APLC)

General Description

The ACT81460 low power PMIC incorporates Active-

Semi’s proprietary ActivePath linear battery charging

architecture. It is a full featured charger that performs a

variety of advanced battery management functions, in-

cluding fault protection and management, thermal reg-

ulation, and temperature monitoring. It includes an

800mA, linear, single cell Li-Ion battery charger and a

Smart Switch. It interfaces to the host microprocessor

via I2C to provide very flexible functionality with its built

in programmability.

The charger is capable of status and fault monitoring

and is designed to work with many different host pro-

cessors via interrupt generation and status and fault re-

porting. Host processor interrupts are generated for any

change in battery charging state:

1) JEITA temp threshold crossed

2) Battery voltage low

3) Battery removed/inserted

4) Charge source plugged/unplugged

5) Charge condition / state change – Precondition, fast

charge, top off and end of charge reached.

ActivePath Architecture

The ActivePath architecture provides a system level

charging architecture that dynamically optimizes battery

charging while ensuring that power delivery to the sys-

tem is not interrupted.

At the input of the ActivePath charger is a high voltage

LDO that can withstand input voltages as high as 20V.

There are variety of protection features such as input

over voltage (OV), input under voltage (UV), input cur-

rent limit. The ActivePath circuity provides a very simple

means of implementing a solution that maximizes avail-

able power from the input source without overloading

the source. An example would be a 0.5A current limited

USB input source. The ActivePath circuit ensures that

the full 0.5A current is used.

ActivePath circuitry automatically detects the state of

the input supply, the battery and the system and then

reconfigures itself to optimize the system power. A

higher priority is always given to system power to en-

sure uninterrupted power to the system. It does this by

independently managing the input current and the

charge current. This allows the battery to charge as

quickly as possible while ensuring that the total

ACT81460 input current does not exceed the input

source capability. This is ideal for weak, or current lim-

ited input sources.

The ActivePath architecture operates in two separate

modes, dynamic charge current control (DCCC) and dy-

namic voltage charge current control (DVCCC).

The DCCC mode can be used for a “weak” input source

when the maximum available current is known. In

DCCC mode, the ACT81460 regulates the total input

current into VIN. This allows the user to set the total in-

put current below the power source’s maximum current

rating. This ensures that the input power source’s cur-

rent rating is not exceeded and that its voltage does not

collapse.

The DCCC loop regulates the input current to the pro-

grammed current limit setting. The system consumes its

required current, and the remaining current is used to

charge the battery. The charging current is dynamically

adjusted as the system current changes.

If the system current exceeds the maximum pro-

grammed input current due to current spikes, the

charger stops charging and goes into supplement mode.

In supplement mode, the battery supplies current to the

system. This maintains the maximum allowable input

current while still allowing the system to run properly.

This maximum input current is programmable to 0.5A,

1A, 1.5A, or 2A via I2C register bits IN_ILIM[1:0]

DVCCC mode can be used to maximize the total avail-

able power from the input source, even when the cur-

rent capability is not known. It also prevents “weak” in-

put sources from collapsing.

The DVCCC loop regulates the input voltage on VIN. If

the system current plus charging current is greater than

the input source’s current capability, the input voltage

collapses. The DVCCC loop becomes active and limits

the VIN current. It also prioritizes the system current

over the charging current. The DVCCC loop starts limit-

ing the charge current when VIN drops to the pro-

grammed threshold. It linearly decreases the charge

current until VIN drops to 0.7V below the threshold. If

the system current continues to increase, the charger

goes into supplement mode and the battery provides

current to the system.

The VDCCC threshold is programmable to “Disable”,

4.25V, 4.5V, or 4.75V via I2C register bits VDCCC[1:0].

When set to “Disable”, the control loop does not limit the

input voltage drop.

Smart Switch

The Smart Switch serves three functions: VSYS

softstart, VSYS linear regulator, and VIN overvoltage

blocking. VSYS is the system voltage, which is limited

ACT81460 Datasheet(PDF) 48 Page - Active-Semi, Inc

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