ACT81460
Rev 1.0, 18-Dec-2018
source capability. This is ideal for weak, or current lim-
ited input sources.
ACTIVE PATH LINEAR CHARGER
(APLC)
The ActivePath architecture operates in two separate
modes, dynamic charge current control (DCCC) and dy-
namic voltage charge current control (DVCCC).
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 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.
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:
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.
1) JEITA temp threshold crossed
2) Battery voltage low
3) Battery removed/inserted
4) Charge source plugged/unplugged
This maximum input current is programmable to 0.5A,
1A, 1.5A, or 2A via I2C register bits IN_ILIM[1:0]
5) Charge condition / state change – Precondition, fast
charge, top off and end of charge reached.
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.
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.
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.
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
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
Innovative PowerTM
ActiveSwitcherTM is a trademark of Active-Semi
www.active-semi.com
Copyright © 2018 Active-Semi, Inc.
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ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
