General Description

The FS3871 Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) linear charge-management ICs are designed for cost sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery conditioning, temperature monitoring, charge termination, charge-status indication, and Automatic charge-rate compensation in a single 8-pin IC. TSSOP package is offered to fit a wide range of end applications.

The FS3871 continuously measures battery temperature using an external thermistor. For safety, the FS3871 inhibits charge until the battery temperature is within user-defined thresholds. The FS3871 then charges the battery in three phases: conditioning, constant current and constant voltage. If the battery voltage is below the low-voltage threshold, V(min), the FS3871 pre-charges using a low current to condition the battery. The conditioning charge rate is approximately 10% of the regulation current. The conditioning current also minimizes heat dissipation in the external pass element during the initial stage of the charge. After conditioning, the FS3871 applies a constant current to the battery. An external sense-resistor sets the current. The sense-resistor can be on either the high or low side of the battery without additional components. The constant-current phase continues until the battery reaches the charge-regulation voltage.

The available 8-pin TSSOP-8/MSOP-8 package is offered for balanced area and cost effective requirements for size-sensitive applications.

The FS3871 is suitable for the control of charge sequences of a variety of portable battery-powered applications, such as cellular phone’s travel and base charger devices, digital camera, digital-video camcorder (DV), MP3 player ,etc.



Ideal for Single (4.1 V or 4.2 V) and Dual-Cell (8.2 V or 8.4 V) Li-Ion or Li-Poly Packs (Dual-Cell is not available now)
0.3 V dropout voltage for minimizing heat dissipation
Better than ±1% voltage regulation accuracy with preset voltages
Automatic Dynamic Compensation of battery packs internal impedance to reduce charge time
Optional cell-temperature monitoring before and during charge
Integrated voltage and current regulation with programmable charge-current and high or low-side current sensing
Integrated cell conditioning for reviving deeply discharged cells and minimizing heat dissipation during initial stage of charge
Charge status output for single or dual LED or host processor interface
Automatic battery-recharge feature
Charge termination by minimum current
Automatic low-power sleep mode when VCC is removed
Low-cost peripheral components of capacitor and resistor combinations for minimum BOM cost in manufacturing considerations
Evaluation (EV) board is available for quick evaluation
TSSOP-8/MSOP-8 Pb-free Package.



Cellular phone external base or built-in charger
MP3/MP4 player
External charger through USB
Digital still camera (DSC)
Digital video camcorder (DV)
Portable electronic device charger, etc.



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