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Li+ battery fuel gauges work without current sensing

Posted: 16 Jul 2010 ?? ?Print Version ?Bookmark and Share

Keywords:fuel gauge? IC?

Maxim has introduced the MAX17040/MAX17041 and MAX17043/MAX17044 1- and 2-cell fuel-gauge ICs.

Using the company's ModelGauge algorithm, these fuel gauges accurately estimate the state of charge (SOC) of a Li+ battery without requiring current sensing. ModelGauge ICs eliminate the current-sense resistor and require very few external components, saving both space and cost. The MAX17040/MAX17041 and MAX17043/MAX17044 also eliminate several other discrete components and the coulomb counter, which results in an overall cost savings of 30% to 50% compared to traditional approaches, according to Maxim.

The chips are well-suited for handheld 1- and 2-cell Li+ battery applications like wireless handsets, smart phones, e-books, portable game players, digital cameras, handheld computers and financial terminals, portable navigation equipment, and portable medical equipment.

According to Maxim, these MAX17040/MAX17041 and MAX17043/MAX17044 fuel gauges use the lowest supply current in the industry (50microamps, typ), which helps maximize the runtime. The 1-cell MAX17040/MAX17043 and 2-cell MAX17041/MAX17044 require only two or three resistors and two capacitors.

The MAX17040/MAX17043's measurement and power-supply inputs connect directly to the battery pack, alleviating the need for a separate regulator. The MAX17041/MAX17044's measurement inputs connect directly to the battery pack and can be powered by 3.3V system power. Additionally, the MAX17043/MAX17044 have a programmable low-battery alert to warn the system microcontroller to take appropriate power-management actions when the battery is nearly empty. This feature further extends the battery life, as the system microcontroller remains in sleep mode longer without having to poll the fuel-gauge IC.

ModelGauge ICs are packaged in a lead-free 8-pin, 2mm x 3mm TDFN. They communicate with the system microprocessor over an industry-standard 2-wire interface.

Prices start at $0.89 (MAX17040), $0.95 (MAX17041), $0.99 (MAX17043), and $1.01 (MAX17044) for orders of at least 10,000 units, FOB United States.

- Ismini Scouras
EE Times

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