LM3620

Lithium-Ion Battery Charger Controller

General Description

The LM3620 series of controllers are monolithic integrated

circuits designed to control the charging and end-of-charge

control for lithium-ion rechargeable batteries. The LM3620 is

available in two versions for one or two cell charger applica-

tions. Each version provides the option of selecting the ap-

propriate termination voltage for either coke or graphite an-

ode lithium cells.

The LM3620 can operate from a wide range of DC input

sources (4V to 30V). With no charger supply connected, the

controller draws a quiescent current of only 10nA to minimize

discharging of a connected battery pack.

The LM3620 consists of an operational transconductance

amplifier, a bandgap voltage reference, a NPN driver transis-

tor and precision voltage setting resistors. The output of the

amplifier is made available to drive an external power tran-

sistor if higher drive currents are required.

curacy, the LM3620 provides a simple, precise solution for

end-of-charge control of lithium-ion rechargeable cells.

The LM3620 is packaged in a miniature 5-lead SOT-23 sur-

face mount package for very compact designs.

Features

n Voltage options for charging 1 or 2 cell stacks

n Adjustable output voltage for coke or graphite anodes

n Precision end-of-charge voltage control

n Wide input voltage range (4V to 30V)

n Drive provided for external power stage

n Tiny SOT-23 package

Typical Application

DS100841-10

June 1999

© 1999 National Semiconductor Corporation

DS100841

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