®
ACT5830
Rev 2, 20-Jan-11
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
FUNCTIONAL DESCRIPTIONS
CC/CV regulation loop, which regulates either
current or voltage as necessary to ensure fast and
safe charging of the battery.
General Description
The ACT5830's internal battery charger is an
intelligent, stand-alone CC/CV (constant-
current/constant-voltage), linear-mode single-cell
charger for Lithium-based cell-chemistries. This
device incorporates current and voltage sense
circuitry, an internal power MOSFET, thermal-
regulation circuitry, a complete state-machine to
implement charge safety features, and circuitry that
eliminates the reverse-blocking diode required by
conventional charger designs. The ACT5830
battery charger operates independently of the
regulators, and is automatically enabled whenever
a valid input supply is available.
In a normal charge cycle, this loop regulates the
current to the value set in the CHGR/ISET register.
Charging continues at this current until the battery
cell voltage reaches the programmed termination
voltage, as defined in the CHGR/VSET register. At
this point the CV loop takes over, and charge
current is allowed to decrease as necessary to
maintain charging at the termination voltage.
Programming the Charge Current (ISET[_])
In order to accommodate both USB and AC-
powered inputs with a minimum of external
The ACT5830's battery charger features software-
programmable fast-charge current, charge
termination voltage, charge safety timeout period.
components, the ACT5830 features
a
I2C-
programmable fast-charge current that requires no
external current-setting components. The
CHGR/ISET register sets ISET to any value greater
than [0000] to program the maximum charge
current to values in the 300mA to 1A via software.
See for a detailed list of programmable charge
currents.
The ACT5830's battery charger can accept input
supplies in the 4.3V to 6V range, making it
compatible with lower-voltage inputs such as 5-6V
wall-cubes and USB ports. The battery charger,
along with LDO1, LDO2, and LDO3, is enabled and
initiates a charging cycle whenever an input supply
is present.
Note that the actual charging current may be lower
than the programmed fast-charge current, due to
the ACT5830's thermal regulation loop. See the
Thermal Regulation section for more information.
Enabling/Disabling the Charger
The ACT5830 is enabled when the voltage applied
to CHG_IN is greater than the voltage at BAT and is
greater than 4.0V, and nENCHG is asserted low.
The charger is disabled whenever nENCHG is high,
independent of the voltages at battery and CHG_IN.
The charger may also be disabled via the I2C
interface.
Measuring the Charge Current
In order to ease monitoring of the charge current,
the ACT5830 generates a voltage at VICHG that is
proportional to the charge current. The gain is
typically 2.47mV/mA, and this voltage can be easily
read by a system ADC. VICHG is high-impedance
in shutdown.
For more information about enabling and disabling
the charger, see the System Startup & Shutdown
section.
Thermal Regulation
The ACT5830 features an internal thermal feedback
loop that reduces the charging current as necessary
to ensure that the die temperature does not rise
beyond the thermal regulation threshold of 115°C.
This feature protects the ACT5830 against
accessing JUNCTION temperature, and allows the
ACT5830 to be used in aggressive thermal designs
without risk of damage. Note that attention to good
thermal design is still required to achieve the fastest
possible charge time.
Operation Without a battery
The ACT5830's charger is designed to operate with
or without a battery connected. When a battery is
connected, a normal charging cycle is performed as
described below. If no battery is present, however,
the charger will regulate the voltage at BAT to the
voltage programmed by CHGR/VSET[_] to power
the system.
CC/CV Regulation Loop
At the core of the ACT5830's battery charger is a
Innovative PowerTM
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