May 2, 2005
Li-ion/Li Polymer Linear Battery Charger
The ISL6291 provides a low-cost integrated charger solution
for single-cell Li-ion and Li Polymer rechargeable batteries.
No external pass element, current sensing resistor, or
reverse blocking diode is required with this solution.
The ISL6291 is a constant-current (CC)/constant-voltage
(CV) charger. The constant charge current is programmable
up to 2.0A with an external signal resistor. An internal
trimmed current-sense circuit guarantees 10% accuracy,
with no bulky external current-sense resistor. The constant
voltage is either 4.1V or 4.2V. The charger always
preconditions the battery with 1/10 of the programmed
charge current at the beginning of a charge cycle, until it
verifies that the battery can be fast-charged. A safety timer
prevents over-charging a dead battery. The charging
terminates as the charge current falls below the
programmed minimum current during the CV mode. The
charger automatically re-charges the battery when the
battery voltage drops below a recharge threshold. A simple
interface with an NTC thermistor avoids charging the battery
outside a programmable temperature window. A thermal-
foldback feature of the ISL6291 guarantees safe operation
when the printed circuit board space is limited for thermal
dissipation. The charger reduces the charge current
automatically, as the internal temperature rises above a
preset level, to prevent further temperature rise.
When the wall adapter is not present, the ISL6291 draws
less than 1A current from the battery. Two logic outputs
provide the charging status and fault information, and an
easy interface to system logic. A V2P8 pin outputs a 2.8V
reference voltage that can be used to bias other circuits, or
as an indication for the adapter presence.
The ISL6291 is packed in a thermally enhanced 5x5 QFN
package. See the Technical Brief TB389 given in the Related
Literature for more information related to the package.
• Integrated Linear Pass Element
• Integrated Charge Current Sensor
• No External Reverse Blocking Diode Required
• 1% Voltage Accuracy
• Programmable Current Limit Up to 2.0A
• Programmable End-of-Charge Current
• Trickle Charge an Over Discharged Battery
• Charge Current Thermal Foldback
• Simple Interface for Low-Cost Thermistor
• Accepts USB Bus Power
• Ambient Temperature Range: -20°C to 70°C
• Thermally-Enhanced 5x5 QFN Package (JA = 33°C/W)
• Pb-Free Available (RoHS Compliant)
• Handheld Devices
• Cell Phones
• Stand-Alone Chargers
• USB Bus-Powered Chargers
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices
• Technical Brief TB389 “PCB Land Pattern Design and
Surface Mount Guidelines for QFN Packages”
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright Intersil Americas LLC. 2005. All Rights Reserved
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