Linear USB Battery Charger with Dual Buck Regulators

The LTC3559/LTC3559-1 are USB battery chargers with dual high efficiency buck regulators. The parts are ideally suited to power single-cell Li-Ion/Polymer based handheld applications needing multiple supply rails.

Battery charge current is programmed via the PROG pin and the HPWR pin, with capability up to 950mA at the BAT pin. The battery charger has an NTC input for temperature qualified charging. The CHRG pin allows battery status to be monitored continuously during the charging process. An internal timer controls charger termination.

Each monolithic synchronous buck regulator provides up to 400mA of output current while operating at efficiencies greater than 90% over the entire Li-Ion/Polymer range. A MODE pin provides the flexibility to place both buck regulators in a power saving Burst Mode operation or a low noise pulse skip mode.

The LTC3559/LTC3559-1 are offered in a low profile thermally enhanced 16-lead (3mm × 3mm) QFN package.

Applications

* SD/Flash-Based MP3 Players

* Low Power Handheld Applications

* Standalone USB Charger

* Up to 950mA Charge Current Programmable via Single Resistor

* HPWR Input Selects 20% or 100% of Programmed Charge Current

* NTC Input for Temperature Qualified Charging

* Internal Timer Termination

* Bad Battery Detection

* CHRG indicates C/10 or Timeout