7

FN9184.0

March 17, 2005

Trickle Charge Current

When the battery voltage is below the minimum battery

operates in a trickle/preconditioning mode, where the charge

current is typically 14% of the programmed charge current

for the cradle input. If power comes from the USB input, the

trickle mode current is approximately 53mA.

End-of-Charge Indication

The CHG pin internal open-drain MOSFET turns off when

programmable for the cradle input and fixed for the USB

input. Once the end-of charge-current is reached, the CHG

status will be latched. The latch can be reset at one of the

following conditions:

1. The part is disabled and re-enabled

2. The selected input source has been removed and re-

applied

3. The USBON turns LOW and turns back to HIGH for the

USB input

4. The BAT pin voltage falls below the CV mode threshold

Regardless of the CHG pin status, however, the charger

does not turn off as long as an input power source is

attached.

Power Presence Indication

When either the USB or the cradle input voltage is above the

POR threshold, the PPR pin internal open-drain MOSFET

turns on indicating the presence of input power.

Power-Good Range

Even if there is a power present, the charger will not deliver

any current to the output if the power-good conditions are

not met. The following two conditions together define the

power-good voltage range:

1. VCDRL or VUSB > VPOR

2. VCDRL or VUSB - VBAT > VOS

where the VOS is the offset voltage for the input and output

voltage comparator, discussed shortly. Both VPOR, VOS

have hysteresis, as given in the Electrical Specification table.

The charger will not charge the battery if the input voltage

does not meet the power-good conditions.

Thermal Foldback (Thermaguard™)

The thermal foldback function reduces the charge current

when the internal temperature reaches the thermal foldback

threshold, which is typically 100°C. This protects the charger

from excessive thermal stress at high input voltages.

ISL6299