LT3653 1.2A, HV Input Regulator with Output Current Limit for Battery Charger Applications FEATURESDESCRIPTION n Wide Input Range: The LT®3653 is a monolithic current mode PWM step-down – Operation from 7.5V to 30V regulator with programmable output current limit. Typically, – Overvoltage Lockout Protects Circuit Through 60V it is used with battery charger power path controllers to Transients pre-regulate the output and optimize the battery charger n Operates with LTC Bat-Track™ Li-Ion Battery effi ciency. Output current limit provides accurate control Chargers to Maximize Effi ciency over system power dissipation. n No Reverse Discharge Path from VOUT to VIN The wide operating input voltage range of 7.5V to 30V n Programmable Output Current Limit suits the LT3653 to a variety of input sources, including n Integrated BOOST Diode unregulated 12V wall adapters, 24V industrial supplies, n Thermal Protection Firewire and automotive power. Input overvoltage protec- n Small Application Size tion allows the LT3653 to handle 60V input transients. n Thermally Enhanced 2mm × 3mm DFN Package The LT3653 control pin, VC, is available for external battery APPLICATIONS tracking control, Bat-Track. The LT3653 will block output discharge during an open or shorted input. n Battery Powered Equipment n Portable USB Devices – Cameras, MP3 Players, The HVOK pin indicates that the internal bias supplies PDAs are present and no faults have occurred (i.e., overtem- n Automotive Battery Regulation perature and input overvoltage and undervoltage). The n Multiple-Source Battery Chargers LT3653 includes a 1.5MHz frequency oscillator, internal compensation, and an internal boost diode to minimize the , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Bat-Track is a trademark of Linear Technology Corporation. All other trademarks are the number of external components. The LT3653 is available property of their respective owners. in an 8-lead (2mm × 3mm) package with exposed pads for low thermal resistance. TYPICAL APPLICATIONHigh Voltage Single-Cell Battery Charger ApplicationEffi ciency vs Load Current 100 V 0.1μF IN 7.5V TO 30V VIN BOOST TRANSIENT 90 TO 60V 4.7μF SW VIN = 8V 4.7μH 80 V LT3653 IN = 12V I V SENSE 1.2A IN = 24V 70 SYSTEM ILIM VOUT LOAD 27.4k 10μF EFFICIENCY (%) 60 OUT HVOK WALL 50 LTC4098 GND VC VC BAT 40 3653 TA01a + 0.1 0.3 0.5 0.7 0.9 1.1 1.3 SINGLE-CELL Li-Ion OUTPUT CURRENT(A) 3653 TA01a 3653f 1
