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.
The LTC3559/LTC3559-1 are USB battery chargers that incorporate two high‑efficiency synchronous buck regulators. They support programmable charge currents up to 950 mA and provide up to 400 mA output per regulator, with options for burst‑mode or pulse‑skip operation to balance noise and efficiency.
The device operates from a 3.5 V to 5.5 V input range, works over –40 °C to 85 °C, and is offered in a 16‑lead 3 mm × 3 mm QFN package. Detailed electrical characteristics, typical performance curves, and package drawings are included for designers.
| Maximum charge current | 950 mA |
|---|---|
| Buck regulator output current | 400 mA per regulator |
| Switching frequency | 2.25 MHz |
| Quiescent current (no‑load) | 355 µA |
| Package | 16‑Lead 3 mm × 3 mm Plastic QFN |
The LTC3559 can be programmed for a charge current up to 950 mA using a single resistor.
It contains two synchronous buck regulators, each capable of delivering up to 400 mA of output current.
In standby (charge terminated) mode the quiescent current is specified as 200 pA to 400 pA.