LM3620 Lithium-Ion Battery Charger Controller
June 1999
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.
With a trimmed output voltage regulation of
±
1.2% initial ac-
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
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Voltage options for charging 1 or 2 cell stacks
Adjustable output voltage for coke or graphite anodes
Precision end-of-charge voltage control
Wide input voltage range (4V to 30V)
Low off state current (
<
10nA)
Drive provided for external power stage
Tiny SOT-23 package
Typical Application
DS100841-10
© 1999 National Semiconductor Corporation
DS100841
www.national.com
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