9

FN9252.1

May 16, 2007

Functional Block Diagram

Theory of Operation

The ISL9205 is an integrated charger for single-cell Li-ion or

Li-polymer batteries. The ISL9205 is capable of operating in

two operation modes, linear charge mode and pulse charge

mode. The ISL9205 functions as a traditional linear charger

when powered with a voltage source adapter. When

powered with a current-limited adapter, the charger functions

as a pulse charger by fully turning on the pass element and

the power dissipation is hence drastically reduced.

Constant Current Phase

The ISL9205 starts the charge at a constant current (CC)

phase. The charge current is regulated to fast charge the

battery before the final voltage has been reached. The

charge current is programmable with the IREF pin and has

two operation modes: trickle mode and constant current

mode, depending on the battery voltage. When the battery

voltage is lower than 2.8V, the charger operates in trickle

mode where the charge current is set at 10% of the constant

current mode current. The trickle mode is for preconditioning

a deeply discharged battery. Once the battery voltage is

above the typical 2.8V threshold, the constant current (CC)

mode starts. The constant current is programmable between

50mA to 1A.

Constant Voltage Phase

When the battery reaches the final voltage, the ISL9205

switches the operation to a constant voltage (CV) phase.

The output voltage is regulated at the final voltage value.

LOGIC

STATUS

ISEN

VIN

VBAT

100000:1

CURRENT

MIRROR

COUNTER

+

-

+

-

VMIN

+

-

+

-

V CH

IREF

+

-

FAULT

RECHARGE

MINBAT

VRECHRG

CA

VA

MIN_I

IR

ISEN

IMIN= IR/10

CHRG

STATUS

FAULT

+

-

+

-

INPUT_OK

V POR

TRICKLE/FAST

REFERENCES

V2P8

TEMPERATURE

MONITORING

CURRENT

REFERENCES

IT

TIME

OSC

GND

VIN

Q MAIN

QSEN

R IREF

C1

VSEN

+

80mV

EN

INPUT_OK

ESD DIODE

TEMP

MONITOR

TEMP

ISL9205