Switch mode USB power manager with integrated 1A buck-boost and I2C interface maximizes battery run time & minimizes heat
(Product News, 03 Jul 2008 )
Linear Technology Corporation has announced the LTC3567, the latest in a family of compact next-generation, multi-function power management solutions for Li-Ion/Polymer battery applications. The LTC3567 integrates a switching PowerPath manager, a stand-alone battery charger, a 1A high efficiency synchronous buck-boost regulator, an ideal diode and controller, I2C control, plus an always-on LDO, all in a compact, low-profile 4mm x 4mm QFN package. The LTC3567's PowerPath control feature seamlessly manages power flow between multiple input sources such as a wall adapter or USB port and the Lithium battery while preferentially providing power to the system load. In addition, its "instant-ON" operation ensures power to the system load even with a depleted battery. For fast charging, the LTC3567's switching input stage converts nearly 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 180milliohm ideal diode plus optional external ideal diode controller provide a low loss power path from the battery to the system load, further minimizing heat generation and maximizing efficiency.
The LTC3567's onboard synchronous buck-boost regulator can deliver up to 1A continuously and is ideal for efficiently regulating a 3.3V output voltage over the full Lithium battery voltage range, down to 2.75V input. The regulator's internal low RDS(ON) switches enable efficiency as high as 94%, maximizing battery run time. In addition, Burst Modeｮ operation optimizes efficiency at light loads with a quiescent current of only 20uA (<1uA in shutdown). The high 2.25MHz switching frequency allows the use of tiny low cost capacitors and inductors less than 1mm in height. Furthermore, the regulators are stable with ceramic output capacitors, achieving very low output voltage ripple.
The LTC3567 features USB-compatible programmable current limiting to 100mA/500mA/1A, while its Bat-Track adaptive output control enables high efficiency battery charging and reduces power dissipation. Stand-alone autonomous operation simplifies design, eliminating the need for an external microprocessor for battery charge termination. To preserve battery energy, the LTC3567 draws only 38uA in suspend mode. The charger is compatible with inputs up to 5.5V (7V absolute maximum transient for added robustness).
