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Standalone battery charger draws power from wall adapter, USB

Posted: 26 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:battery charger? wall adapter? USB? Linear Tech? xx?

Linear Technology Corp. has introduced the LTC4097 standalone dual-input linear battery charger. This device charges single-cell Li-ion/polymer batteries from wall adapter or USB power sources. It uses a constant-current/constant-voltage algorithm for charging, with programmable charge current up to 0.2A from a wall adapter supply or up to 1A from a USB supply, while automatically detecting the presence of voltage at each input. USB current limiting is also provided. Applications include PDAs, MP3 players, digital cameras, lightweight portable medical and test equipment and large color display cell phones.

The LTC4097 features a final float voltage accuracy of 0.6 percent and is equipped with a patented thermal regulation scheme that maximizes the charging rate without the risk of overheating. The device is flexible with the following features programmable via a single resistor: wall adapter supply charge current, USB supply charge current and charge termination current. As a standalone charger, it does not require an external MCU to terminate charge, simplifying design. Key features include automatic input source selection, a combined input Power Present Output and NTC bias (VNTC) pin with 120mA drive capability, an NTC Thermistor Input (NTC) pin for temperature-qualified charging, and a USB charge current level select (HPWR) pin for obtaining 20 percent or 100 percent of the current programmed via the IUSB pin. Other features include trickle charge for battery pre-conditioning, undervoltage lockout, automatic recharge and charge status indication.

The LTC4097 is offered in a low-profile (0.75mm) 12-lead 2-by-3mm DFN package. The total solution footprint is compact since no external MOSFET, sense resistor or blocking diode is required. To extend battery run time, the LTC4097 draws <50?A in standby and < 20?A in shutdown mode.

The LTC4097 is rated for operation from -40C to 85C. Pricing for 1,000 pieces begins at $1.56 each.

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Related Datasheets
Part Number Description Category
? LTC4097 USB/Wall Adapter Standalone Li-Ion/Polymer Battery Charger ICs, Interface



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