Industry's first lithium ion battery charge controller

Designed for charge and end-of-charge control of rechargeable Lithium-ion (Li-ion) batteries, the new LM3420 controller is now being introduced by National Semiconductor Corporation. This product, an example of National's innovative technologies for shaping information, can be used in a variety of battery charging approaches including, linear charging, switching charging, or isolated high efficiency switching charging.

Internal circuitry includes a precision bandgap reference, an internally compensated op amp, voltage setting resistors and an NPN output driver for feedback control. The LM3420 is offered in two tolerance grades, A (+/-0.5%) and Standard (+/-1%), to meet the precision charging requirements of Li-ion batteries. The LM3420's NPN output transistor is capable of driving up to 15mA of output current into external circuitry and simplifies feedback control circuitry. The trimmed precision bandgap reference uses temperature drift curvature correction to provide excellent voltage stability over the operating temperature range of -40ºC to +85ºC ambient.

Available in the 5-pin, SOT-23 package (20 % the footprint and 50 % the profile of an 8-pin SOIC), the TinyPak(tm) LM3420 is available in 4.2, 8.4 and 12.6V versions for one, two and three cell charger applications. With the use of an external resistor, the LM3420 is also compatible with 4.1, 8.2, and 12.3V Li-ion series cells. Moreover, LM3420's TinyPak(tm) Sot-23 package is ideally suited for including charge control circuitry inside the battery pack.

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Sandra Ade is a successful author and regular contributor to http://www.1st-in-batteries.com. A great resource for all kinds of batteries to be used for camcorders, laptops, cell phones and more.

	Battery Charging
Industry's first lithium ion battery charge controller