ACT8933
Rev 3, 15-Nov-12
include pin-programmable fast-charge current and
one current-limited nSTAT output that can directly
drive LED indicator or provide a logic-level status
a logic-high, or 100mA, if CHGLEV is driven to a
logic-low.
The ACT8933's charge current settings are
summarized in Table 10.
signal to the host microprocessor.
Dynamic Charge Current Control (DCCC)
Note that the actual charge current may be limited
to a current lower than the programmed fast charge
current due to the ACT8933’s internal thermal
regulation loop. See the Thermal Regulation section
for more information.
The ACT8933's ActivePath charger features
dynamic charge current control (DCCC) circuitry,
which acts to ensure that the system remains
powered while operating within the maximum output
capability of the power adapter. The DCCC circuitry
continuously monitors VVSYS, and if the voltage at
VSYS drops by more than 200mV, the DCCC
circuitry automatically reduces charge current in
order to prevent VVSYS from continuing to drop.
Charger Input Interrupts
In order to ease input supply detection and
eliminate the size and cost of external detection
circuitry, the charger has the ability to generate
interrupts based upon the status of the input supply.
This function is capable of generating an interrupt
when the input is connected, disconnected, or both.
An interrupt is generated any time the input supply
is connected when INSTAT[ ] bit is set to 1 and the
INCON[-] bit is set to 1, and an interrupt is
generated any time the input supply is disconnected
when INSTAT[ ] bit is set to 1 and the INDIS[ ] bit is
set to 1.
Charge Current Programming
The ACT8933's ActivePath charger features a
flexible charge current-programming scheme that
combines the convenience of internal charge
current programming with the flexibility of resistor
based charge current programming. Current limits
and charge current programming are managed as a
function of the ACIN and CHGLEV pins, in
combination with RISET, the resistance connected to
the ISET pin.
INDAT[-] indicates the status of the CHGIN input
supply. A value of 1 indicates that a valid CHGIN
input (CHGIN UVLO Threshold<VCHGIN<CHGIN
OVP Threshold) is present, a value of 0 indicates a
valid input is not present.
ACIN is a logic input that configures the current-limit
of ActivePath's linear regulator as well as that of the
battery charger. ACIN features a precise 1.2V logic
threshold, so that the input voltage detection
threshold may be adjusted with a simple resistive
voltage divider. This input also allows a simple, low-
cost dual-input charger switch to be implemented
with just a few, low-cost components.
When an interrupt is generated by the input supply,
reading the INSTAT[ ] returns a value of 1.
INSTAT [ ] is automatically cleared to 0 upon
reading. When no interrupt is generated by the
input supply, reading the INSTAT[ ] returns a value
of 0.
When the voltage at ACIN is above the 1.2V
threshold, the charger operates in “AC-Mode” with a
charge current programmed by RISET, and the RISET
is given by:
When responding to an Input Status Interrupt, it is
often useful to know the state of the ACIN input. For
example, in
a
dual-input charger application
knowing the state of the ACIN input can identify
which type of input supply has been connected. The
state of the ACIN input can be read at any time by
reading the ACINSTAT[-] bit, where a value of 1
indicates that the voltage at ACIN is above the 1.2V
threshold (indicating that a wall-cube has been
attached), and a value of 0 indicates that the
voltage is below this threshold (indicating that ACIN
input is not valid and USB supply input is selected).
R
ISET (kꢀ) = 2336 × (1V/ICHG (mA)) - 0.205
With a given RISET then charge current will reduce 5
times when CHGLEV is driven low.
When ACIN is below the 1.2V threshold, the
charger operates in “USB-Mode”, with a maximum
CHGIN input current and charge current defined by
the CHGLEV input; 450mA, if CHGLEV is driven to
Table 10:
ACIN and CHGLEV Inputs
CHARGE CURRENT
PRECONDITION CHARGE CURRENT
(mA)
ACIN
CHGLEV
(mA)
0
0
1
1
0
1
0
1
90
45
450
45
I
CHG/5
ICHG
10% × ICHG
10% × ICHG
Innovative PowerTM
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