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Linear Technology has launched the LTC3577, LTC3577-1, LTC3577-3 and LTC3577-4, highly integrated multi-function power management integrated circuits for portable Li-ion/polymer battery applications.

The LTC3577/-X integrates a USB-compatible linear Powerpath manager, a standalone battery charger, over-voltage protection, 10-LED driver, pushbutton on/off control, three high-efficiency synchronous buck regulators and two LDOs in a low-profile 4 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 said to be suitable for portable device applications including personal navigation devices, digital media/video broadcasting, digital/satellite radio, media players, universal remotes, photo viewers and portable medical and industrial devices.

The LTC3577/-X’s Powerpath manager with automatic load prioritisation 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 over-voltage protection 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

The LTC3577/-1 can control an external high-voltage buck regulator to achieve high-efficiency Bat-Track 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 per cent 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 per cent, further maximising battery run time.

In addition, I2C-controlled Burst Mode operation optimises efficiency at light loads with a quiescent current of only 20uA per regulator (

Furthermore, the regulators are stable with ceramic output capacitors, achieving 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) 4 x 7mm QFN-44 package.

Linear Technology now part of Analog Devices

Analog Devices (NASDAQ: ADI) is the leading global high-performance analog technology company dedicated to solving the toughest engineering challenges.

About Analog Devices
Analog Devices (NASDAQ: ADI) is the leading global high-performance analog technology company dedicated to solving the toughest engineering challenges. We enable our customers to interpret the world around us by intelligently bridging the physical and digital with unmatched technologies that sense, measure, power, connect and interpret. Visit http://www.analog.com

 

 

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