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USB Power Manager with Integrated
1A Buck-Boost Circuit

The LTC3567's onboard synchronous buck-boost regulator can deliver up to 1A continuously

Linear Technology Corporation Press Release - 6/25/2008

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LTC 3567 Switching Regulator Efficiency

LTC 3567 Switching Regulator Efficiency

MILPITAS, Ca. - Linear Technology Corporation announces 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® operation optimizes efficiency at light loads with a quiescent current of only 20uA (<1µA 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).

The LTC3567 is available from stock in a compact, low-profile (0.75mm) 4mm x 4mm QFN-24 package. Pricing starts at $3.85 each for 1,000-piece quantities.

Summary of Features: LT C3567

• Complete Multi-Function PMIC: Switching Power Manager, Li-Ion/Polymer Battery
• Charger, 1A Buck-Boost Regulator & LDO
• I2C Control
• Thermally Enhanced, Low Profile (0.75mm) 24-Lead 4mm x 4mm QFN Package
• Power Manager & Battery Charger
• High Efficiency Switching PowerPath Controller with Bat-Track Adaptive Output Control
• Maximum Charge Current Programmable up to 1.5A from Wall Adapter
• Up to 700mA Charge Current from USB Port
• DC/DC Converters
• High Efficiency Buck-Boost Regulator: 1A IOUT
• Buck-Boost Regulator Adjustable Output Voltage Range: 2.75V to 5.5V
• Burst Mode Operation for Low IQ: 20µA for Buck-Boost Regulator
• Always-On 3.3V/25mA LDO

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