Switching power IC allows faster charge time

Linear Technology Corp. has released the LTC3555, the first in a family of next generation multi-function power management solutions for Li-ion/polymer battery applications.

LTC3555 integrates a switching PowerPath manager, a standalone battery charger, an ideal diode, I?C control, three high efficiency synchronous buck regulators plus an always-on LDO, all in a compact, low-profile 4-by-5mm QFN package.

The PowerPath control feature of the device seamlessly manages power flow between an AC wall adapter or USB port, Li-ion battery and system load while its "instant-ON" operation ensures system load power even with a dead or missing battery. For fast charging, LTC3555's switching input stage converts almost all of the 2.5W available from the USB port to charging current, enabling up to 700mA from a 500mA limited USB supply and up to 1.5A when wall powered. An internal 180mΩ ideal diode plus optional external ideal diode controller provide a low loss power path, further minimizing heat generation and maximizing efficiency.

The chip's three integrated synchronous buck regulators feature 100 percent duty cycle operation and are capable of delivering output currents of 1A/400mA/400mA, respectively, with adjustable output voltages down to 0.8V. The internal low R_ds(on) switches enable efficiency of up to 94 percent, maximizing battery runtime. Moreover, Burst Mode operation optimizes efficiency at light loads with a quiescent current of only 35?A per regulator (LTC3555 features USB-compatible programmable current limiting to 100mA/500mA/1A, while its Bat-Track adaptive output control enables high efficiency charging and reduces power dissipation.

Standalone autonomous operation simplifies design, eliminating the need for an external MCU for charge termination. To preserve battery energy, the LTC3555 draws The device is available from stock in a compact, low-profile (0.75mm) 4-by-5mm QFN-28 package. Pricing starts at $4.65 each for 1,000-piece quantities.