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USB Single Cell LiPoly Charger
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Rodrigo Forrequi lubiana@gmail.com hypertext transfer protocol://rusticengineering.wordpress.com March 10, 2010

Rodrigo Forrequi email: lubiana@gmail.com http://rusticengineering.wordpress.com
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USB Single Cell LiPoly Charger
atomic number 3 Polymer Battery stationr
Introduction
Lithium Polymer Batteries be a very common source of power today. umteen electronics gadgets have one inside, and they have some reasonable features. Ive bought great batteries, with different sizes and capacities for my electronics projects. So long Im using this batteries, coming the problem: charge them.

Charger, Version 1
So, we take leave to ?nd the correct circuit for my DIY charger. After some Google look into I found the Maxim MAX1811 IC. Its a single-cell Lithium battery charger that can be powered directly from a USB or from an external supply up to 6.5V. Its use a SO-8 Package, easy to solder and can be sampled at Maxim. Other chip features are: You can engage between 4.1V and 4.2V battery regulation point; You can tell apart between 100mA and 500mA certain drain from USB; Theres a open drain pin (pin_8) for signaling end of charge condition (2.



5V < VBATT < BATT Regulation Voltage); A internal thermal closed circuit limits the MAX1811 die temperature to +135°C by reducing the charging current as necessary. According to datasheet, MAX1811 is speci?cally made for USB devices. The minimum potential difference to a common USB-powered device may be as moo as 4.35V when cable and connector drops are considered. The MAX1811 is optimized for operation at these low input voltage levels. But USB hubs may also provide as much as 5.5V!. At highschool input voltages (5.5V) and low cell voltages (2.7V), the MAX1811s thermal closed circuit may limit the charge current until the cell voltage rises. My design uses 500mA was charging current (pin 2 - SELI - pulled up), but MAX1811 only taken this current if the device is a USB powered source. The other separate are two very common tantalum capacitors and...If you fatality to get a full essay, order it on our website: Orderessay



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