1 Features

1• Input Voltage Range: up to 20 V

• Voltage Options for Charging 1, 2, 3, or 4 Cells

• Output Current up to 15 mA

• Precision (0.5%) End-of-Charge Control

– LM3420 ±1%

– LM3420A ±0.5%

• Drive Capability for External Power Stage

• Temperature Drift Curvature Correction for

Voltage Stability

• Low Quiescent Current, 85 μA (Typ.)

• Tiny SOT-23-5 package

2 Applications

• Lithium-Ion Battery Charging

• Suitable for Linear and Switching Regulator

Charger Designs

3 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 an 8.4-V version for one

through four cell charger applications.

Included in a very small package is an (internally

compensated) op amp, a bandgap reference, an NPN

output transistor, and voltage setting resistors. The amplifier's inverting input 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. The LM3420 series allows for precision end- of-charge voltage threshold for lithium-ion

rechargeable batteries. The premium grade LM3420A

is available with an initial voltage threshold tolerance

of ±0.5%, while the standard grade LM3420 has an

initial voltage threshold tolerance of ±1%.

The LM3420 is available in a sub-miniature 5-lead

surface mount package thus allowing very compact

designs.