7

FN6435.0

February 25, 2008

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. VIN > VPOR

2. VIN - VOUT > VOS

3. VIN < VOVP

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"

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:

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. Enable signal being toggled

3. A recharge cycle starts when the battery voltage drops

below the recharge threshold

The CHG signal can be interfaced either with a

micro-processor 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

by removing and reapplying the input power to the IC.

Under the EOC, timeout and timeout fault conditions, the

power delivery to VOUT 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 1M

Ω 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 VIN, 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 VIN 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