LM3420-4.2 Datasheet, PDF (1/17 Pages) National Semiconductor (TI) – Lithium-Ion Battery Charge Controller

July 2000
LM3420-4.2, -8.2, -8.4, -12.6, -16.8
Lithium-Ion Battery Charge Controller
General Description
The LM3420 series of controllers are monolithic integrated
circuits designed for charging and end-of-charge control for
Lithium-Ion rechargeable batteries. The LM3420 is available
in five fixed voltage versions for one through four cell charger
applications (4.2V, 8.2V/8.4V, 12.6V and 16.8V respec-
tively).
Included in a very small package is an (internally compen-
sated) op amp, a bandgap reference, an NPN output transis-
tor, and voltage setting resistors. The amplifier’s inverting in-
put is externally accessible for loop frequency
compensation. The output is an open-emitter NPN transistor
capable of driving up to 15 mA of output current into external
circuitry.
A trimmed precision bandgap reference utilizes temperature
drift curvature correction for excellent voltage stability over
the operating temperature range. Available with an initial tol-
erance of 0.5% for the A grade version, and 1% for the stan-
dard version, the LM3420 allows for precision end-of-charge
control for Lithium-Ion rechargeable batteries.
The LM3420 is available in a sub-miniature 5-lead SOT23-5
surface mount package thus allowing very compact designs.
Features
n Voltage options for charging 1, 2, 3 or 4 cells
n Tiny SOT23-5 package
n Precision (0.5%) end-of-charge control
n Drive capability for external power stage
n Low quiescent current, 85 µA (typ.)
Applications
n Lithium-Ion battery charging
n Suitable for linear and switching regulator charger
designs
Typical Application and Functional Diagram
DS012359-1
Typical Constant Current/Constant Voltage
Li-Ion Battery Charger
DS012359-2
LM3420 Functional Diagram
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© 2000 National Semiconductor Corporation DS012359
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