Linear Technology introduces the LTC4097 standalone dual-input linear battery charger. This device charges single-cell Li-Ion/Polymer batteries from wall adapter or USB power sources. The LTC4097 uses a constant-current/ constant-voltage algorithm for charging, with programmable charge current up to 1.2A 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% and is equipped with a patented thermal regulation scheme that maximizes the charging rate without the risk of overheating. The device is extremely 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 microcontroller 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% or 100% 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 2mm x 3mm DFN package. The total solution footprint is very compact since no external MOSFET, sense resistor or blocking diode is required. To extend battery run time, the LTC4097 draws <50uA in standby and <20uA in shutdown mode. The LTC4097 is rated for operation from -40°C to 85°C. 1,000-piece pricing begins at $1.56 each.