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Features
Automatic end-of-charge control
Preset or user adjustable charge current regulation
LED drivers for charging status and fault indication
Battery self-discharge refresh (maintenance)
Overvoltage/overcurrent fault detection and protection
Defective battery pack detection
Charge current boost control for cellular phone applications
Charge interruption control input
Description The LM3621 is a full function constant voltage, constant current (CVCC) lithium-ion (Li+) battery charger controller. It
provides 1% regulation accuracy over the specified temperature range without requiring the use of external precision resistors.
The IC controls five charge modes: conditioning, fast, top-off, monitor and maintenance. In addition, the LM3621 detects
and flags defective batteries as well as over current and over voltage fault events. The architecture of the IC is based
on high gain constant voltage and constant current control loops.
The LM3621 is designed to control a switching charger, a linear charger or an off-line ac adapter charger.
The LM3621 consists of a logic controller, precision bandgap reference, wide bandwidth transconductance error amplifiers,
comparators, and an output buffer. The LM3621 is available in a 16-pin SOIC package and is specified over the range of 0°C
to 70°C.
Key Specification
Tight output voltage accuracy (±0.5% at TA = 25°C)
Two selectable output voltages (4.2V or 4.1V)
Less than 1 µA current drain from fully charged battery
Preconditioning severely discharged cells (0V to 2.55V)
Applications
Complete, full function, protected battery charger for coke or graphite anode, single cell Lithium-Ion battery packs
Linear voltage regulator controlled chargers
High efficiency switching regulator controlled chargers
Cost effective wall adapter chargers
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