7
FN6435.3
September 21, 2011
The ISL9301 accepts an input voltage up to 28V but will be
disabled when the input voltage exceeds the OVP threshold,
minimum 10V, to protect against unqualified or faulty AC
adapters.
PPR Indication
The PPR pin is an open-drain output to indicate the
presence of the AC adapter. Whenever the input voltage is
higher than the POR threshold, the PPR
pin turns on the
internal open-drain MOSFET to indicate a logic LOW signal.
When the internal open-drain FET is turned off, the PPR
pin
should leak less than 1µA current. When turned on, the PPR
pin should be able to sink at least 10mA current under all
operating conditions.
The PPR
pin can be used to drive an LED (see “Typical
Application Circuit” on page 6) or to interface with a
microprocessor.
Power-Good Range
The power-good range is defined by the following three
conditions:
1. V
IN
> V
POR
2. V
IN
- V
OUT
> V
OS
3. V
IN
< V
OVP
where VOS is the offset voltage for the input and output
voltage comparator and the VOVP is the overvoltage
protection threshold given in the "Electrical Specifications"
beginning on page 2. All V
POR
, V
OS
, and V
OVP
have
hysteresis. The IC will not deliver any output if the input
voltage is not in the power-good range.
CHG Indication
The CHG is an open-drain output. The open drain FET turns
on when the charger starts to charge and turns off when the
EOC condition is qualified. Once the EOC condition is
qualified, the CHG
signal is latched in off state. The EOC
condition is qualified when both of the following conditions
are satisfied:
1. V
BAT
> V
RECHG
2. I
CHG
< I
MIN
The CHG indication will not be turned on again until a
recharge condition is qualified. A recharge condition is
reached under one of the three conditions:
1. Input power being re-cycled
2. A recharge cycle starts when the battery voltage drops
below the recharge threshold
The CHG
signal can be interfaced either with a
microprocessor GPIO or a LED for indication. A de-glitch
delay of 1ms for both edges is required to prevent nuisance
triggering due to some transient conditions.
Charge Termination, Recharge and Timeout
When an EOC condition is reached, the CHG pin changes to
logic HI to indicate the end-of-charge. However the charger
continues to deliver current to the battery until the timeout
interval has elapsed, then the charging will be terminated.
The setting of the timeout interval is described in “Intelligent
Timer” on page 8. When a recharge condition is met after a
timeout event, the timer will be reset to zero and the
charging re-starts.
In the event when the timeout interval has elapsed before
the EOC condition is reached, a timeout fault condition is
triggered. The timeout fault condition is indicated by the
CHG
pin being toggled between HI and LO every 3s
(R
TIME
=1MΩ). The timeout fault condition can be cleared
by removing and reapplying the input power to the IC.
Under the EOC, timeout and timeout fault conditions, the
power delivery to V
OUT
is not impacted. The battery
continues to supply current to VOUT if needed, as described
in “Dynamic Power Path Management” on page 8.
Battery Disconnection
The BATON pin provides an option for disconnection of the
battery from the system if battery power is not needed and
no power source is applied at VIN. The disconnection will
prevent the IC leakage current from draining the battery for
an extended period of time. To reconnect the battery, pull the
BATON pin to logic HI for 2s. Once the system is powered
on, the host micro process will send a logic signal to keep
BATON at logic HI level. The BATON pin has a 1MΩ internal
pull-down resistor thus, when left floating, the input is
equivalent to a logic LOW state. The logic threshold levels
are given in the "Electrical Specifications" table starting on
page 2.
BATON Interlock
When a valid voltage source is applied at V
IN
, the BATON
function is disabled. This prevents the battery from being
connected to a 4.5V regulated voltage source and
generating a large circulating current. If the V
IN
supply is
removed, the BATON function will resume immediately to
allow the battery to supply the system.
IREF Pin Function
The IREF pin has the two functions as described in “Pin
Descriptions” on page 4. When setting the fast charge
current, the charge current is trimmed to have 10% accuracy
at 145mA, excluding the programming resistor error. The
percent error decreases as the set charge current is higher
but increases as the set charge current is lower than 145mA.
The trickle charge current is 16% of the programmed fast
charge current.
When monitoring the charge current, the accuracy of the
IREF pin voltage vs the actual charge current has the same
accuracy as the gain from the IREF pin current to the actual
charge current. The IREF pin voltage vs the charge current
ISL9301
