LTC3556| Datasheet

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FEATURES
POWER MANAGER n High Efficiency Switching PowerPathTM Controller with Bat-TrackTM Adaptive Output Control n Programmable USB or Wall Current Limit (100mA/500mA/1A) n Full Featured Li-Ion/Polymer Battery Charger n Instant-On Operation with a Discharged Battery n 1.5A Maximum Charge Current n Internal 180m Ideal Diode Plus External Ideal Diode Controller Powers Load in Battery Mode n Low No-Load I when Powered from BAT (<30A) Q DC/DCs n Dual High Efficiency Buck DC/DCs (400mA/400mA I OUT) n High Efficiency Buck-Boost DC/DC (1A I ) OUT n All Regulators Operate at 2.25MHz n Dynamic Voltage Scaling on Two Buck Outputs n I2C Control of Enables, Mode, Two V OUT Settings n ENALL Pin with Power-Up Sequence Control n Low No-Load Quiescent Current: 20A Each

LTC3556 High Efficiency USB Power Manager with Dual Buck and Buck-Boost DC/DCs DESCRIPTION
The LTC 3556 is a highly integrated power management and battery charger IC for Li-Ion/Polymer battery applications. It includes a high efficiency current limited switching PowerPath manager with automatic load prioritization, a battery charger, an ideal diode, and three synchronous switching regulators (two bucks and one buck-boost). Designed specifically for USB applications, the LTC3556's switching power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for adapter-powered applications. The LTC3556's switching input stage transmits nearly all of the 2.5W available from the USB port to the system load with minimal power wasted as heat. This feature allows the LTC3556 to provide more power to the application and eases the constraint of thermal budgeting in small spaces. The two buck regulators can provide up to 400mA each and the buck-boost can deliver 1A. The LTC3556 is available in the low profile 28-pin (4mm 5mm 0.75mm) QFN surface mount packa
ge.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PowerPath and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6522118 and 6404251.

APPLICATIONS
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HDD-Based MP3 Players, PDAs, GPS, PMPs Other USB-Based Handheld Products

TYPICAL APPLICATION
High Efficiency PowerPath Manager, Dual Buck, Buck-Boost and LDO
USB/WALL 4.5V TO 5.5V USB COMPLIANT STEP-DOWN REGULATOR CC/CV BATTERY CHARGER CHARGE T LTC3556 ALWAYS ON LDO ENALL SEQ I2C 3 DUAL HIGH EFFICIENCY BUCKS HIGH EFFICIENCY BUCK-BOOST I2C PORT 1 2 3 3.3V/25mA 0.8V TO 3.6V/400mA 0.8V TO 3.6V/400mA RTC/LOW POWER LOGIC MEMORY CORE P 0V OPTIONAL TO OTHER LOADS 700 600 CHARGE CURRENT (mA) 500 400 300 200 100 0 2.8 3 VBUS = 5V 5X MODE BATTERY CHARGER PROGRAMMED FOR 1A 3.2 3.4 3.6 3.8 BATTERY VOLTAGE (V) 4 4.2

Battery Charge Current vs Battery Voltage
BATTERY CHARGE CURRENT EXTRA CURRENT FOR FASTER CHARGING 500mA USB CURRENT LIMIT

Li-Ion

2.5V to 3.3V/1A PGOODALL

HDD/IO
3556 TA01

3556 TA01b

3556f