Low-Profile PMIC integrates linear power manager, charger.
August 6, 2009 -
Supplied in 4 x 7 x 0.75 mm QFN package, LTC3577/-1/-3/-4 multifunction power management integrated circuits (PMICs) are suited for portable Li-Ion/Polymer battery applications. They integrate USB-compatible linear PowerPath(TM) manager, standalone battery charger, overvoltage protection, 10-LED driver, pushbutton on/off control, 3 synchronous buck regulators, and two 150 mA LDOs. Battery float voltage ratings help improve battery cycle life and run time.
LTC3577-1: 4mm x 7mm PMIC Integrates Linear Power Manager & Charger, Three Buck Regulators, LED Driver, OVP & Pushbutton Control
MILPITAS, CA - July 29, 2009 - Linear Technology Corporation announces the LTC3577, LTC3577-1, LTC3577-3 and LTC3577-4, highly integrated multi-function power management integrated circuit (PMIC) solutions for portable Li-Ion/Polymer battery applications. The LTC3577/-X integrates a USB-compatible linear PowerPath(TM) manager, a standalone battery charger, overvoltage protection, 10-LED driver, pushbutton on/off control, three high efficiency synchronous buck regulators and two LDOs in a low-profile 4mm x 7mm QFN package. The LTC3577-1 and LTC3577-4 feature a 4.1V battery float voltage for improved battery cycle life and additional high temperature safety margin, while the LTC3577 and LTC3577-3 include a standard 4.2V battery float voltage for maximum run time. The LTC3577-3 and LTC3577-4 are tailored for SiRF Atlas IV chipsets. These ICs are highly suited for portable device applications including personal navigation devices (PNDs), digital media/video broadcasting (DMB/DVBs), digital/satellite radio, media players, universal remotes, photo viewers and portable medical and industrial devices.
The LTC3577/-X's PowerPath manager with automatic load prioritization seamlessly manages the transition between multiple input sources to power the load, while delivering up to 1.5A battery charge current from a wall adapter supply or up to 500mA charge current from a USB port. The charger is compatible with inputs up to 5.5V (7V absolute maximum transient for added robustness). The ICs "instant-on" operation ensures system load power even with a fully discharged battery. Autonomous operation simplifies design, eliminating the need for an external microprocessor for charge termination. An overvoltage protection (OVP) controller enables up to 30V protection for the Wall/USB input, while a high temperature battery voltage reduction circuit improves battery safety and reliability. To preserve battery energy during long periods of inactivity or to reset the product in the event of a software lockup, the LTC3577/-1 contains a hard reset function enabled via pushbutton control, placing the IC into an ultra-low quiescent current state that draws <10uA and disables all power supplies and power paths.
The LTC3577/-1 can control an external high-voltage buck regulator to achieve high efficiency Bat-Track(TM) charging and power path control from a high voltage source, reducing power dissipation. The internal 200mOhm ideal diode, plus an optional external ideal diode controller provide a low loss power path to the load when input current is limited or unavailable.
The LTC3577/-X's three integrated synchronous buck regulators feature 100% duty cycle operation and are capable of delivering output currents of 800/500/500mA respectively, with adjustable output voltages down to 0.8V. A high 2.25MHz switching frequency allows the use of tiny low cost capacitors and inductors less than 1mm in height. Internal low RDS(ON) switches enable efficiencies as high as 95%, further maximizing battery run time. In addition, I2C-controlled Burst Mode® operation optimizes efficiency at light loads with a quiescent current of only 20uA per regulator (<1uA in shutdown). Furthermore, the regulators are stable with ceramic output capacitors, achieving very low output voltage ripple.
Additional features of the LTC3577/-X include a 40V series backlight 10-LED driver with I2C controlled 60dB brightness (1000:1 dimming range) and gradation control, pushbutton on/off control with system reset, and dual 150mA current limited LDOs.
The LTC3577/-X is available from stock in a compact, low-profile (0.75mm) 4mm x 7mm QFN-44 package. Pricing starts at $4.95 each for 1,000-piece quantities. For more information, visit www.linear.com.
SUMMARY OF FEATURES: L TC3577, LTC3577-1, LTC3577-3 & LTC3577-4
Complete Multi-Function PMIC: Linear Power Manager, Li-Ion/Polymer Battery Charger, Three Synchronous Buck Regulators, 10-LED Driver, Dual 150mA LDOs, Pushbutton On/Off Control
Charge Current Programmable up to 1.5A from Wall Adapter Input
Seamless Transition Between Input Power Sources: Li-Ion/Polymer Battery, USB, 5V Wall Adapter or High Voltage Buck Regulator with Bat-Track Adaptive Output Control
200mOhm Internal Ideal Diode Plus Optional External Ideal Diode Controller Provides Low Loss Power Path from Battery to Load
Standalone Autonomous Operation
High Temperature Battery Voltage Reduction Circuit for Improved Battery Safety & Reliability
Instant-On Operation with Discharged Battery
DC/DCs
Three High Efficiency Synchronous Buck Regulators with Burst Mode Operation
Buck Regulator Adjustable Output Voltage Range: 0.8V to VBAT
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