The LTC3557/LTC3557-1 is a highly integrated power management and battery charger IC for single cell Li-Ion/ Polymer battery applications. It includes a PowerPathTM manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3557/LTC3557-1 power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for wall adapter powered applications. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit. The LTC3557/LTC3557-1 also includes three adjustable synchronous step-down switching regulators and a high voltage buck regulator output controller with Bat-Track that allows efficient charging from supplies as high as 38V. The LTC3557/LTC3557-1 is available in a low profile 4mm × 4mm × 0.75mm 28-pin QFN package.
The LTC3557/LTC3557-1 combines a PowerPath™ manager, a Li‑ion/Polymer battery charger, an ideal diode, and three adjustable synchronous step‑down switching regulators in a low‑profile 4 mm × 4 mm QFN package. It provides seamless transition between USB, wall‑adapter, and high‑voltage buck sources, with built‑in over‑temperature and over‑current protection.
Typical applications include USB‑powered handheld devices, MP3 players, GPS units, and other portable electronics that require efficient power conversion and battery management. The device supports input voltages up to 38 V and offers programmable charge currents up to 1.5 A.
| Input Supply Voltage | 4.35 V – 5.5 V (typ) |
|---|---|
| Maximum Input Current (1× mode) | 100 mA |
| Regulated Output Voltage (LTC3557) | 4.179 V – 4.221 V (typ) |
| Maximum Charge Current | 1.5 A |
| Package | 28‑Lead Plastic QFN (4 mm × 4 mm) |
| Efficiency (3.3 V output, 400 mA) | ≈90 % |
The device operates with an input supply voltage from 4.35 V to 5.5 V (typical).
It can deliver up to 1.5 A of charge current with thermal limiting.
The IC includes three adjustable synchronous step‑down switching regulators.
It is offered in a 28‑lead plastic QFN package measuring 4 mm × 4 mm.