LT3508 Dual Monolithic 1.4A Step-Down Switching Regulator FEATURESDESCRIPTION n Wide Input Voltage Range: 3.7V to 36V The LT®3508 is a dual current mode PWM step-down n Two 1.4A Output Switching Regulators with Internal DC/DC converter with internal power switches capable Power Switches of generating two 1.4A outputs. The wide input voltage n Adjustable 250kHz to 2.5MHz Switching Frequency range of 3.7V to 36V makes the LT3508 suitable for reg- n Synchronizable over the Full Frequency Range ulating power from a wide variety of sources, including n Anti-Phase Switching Reduces Ripple automotive batteries, 24V industrial supplies and unreg- n Uses Small Inductors and Ceramic Capacitors ulated wall adapters. Both converters are synchronized n Accurate Programmable Undervoltage Lockout to a single oscillator programmable up to 2.5MHz and n Independent Tracking, Soft-Start and Power Good run with opposite phases, reducing input ripple current. Circuits Ease Supply Sequencing Its high operating frequency allows the use of small, low n Output Adjustable Down to 800mV cost inductors and ceramic capacitors, resulting in low, n Small 4mm × 4mm 24-Pin QFN or 16-Pin Thermally predictable output ripple. Each regulator has independent Enhanced TSSOP Surface Mount Packages tracking and soft-start circuits and generates a power n AEC-Q100 Qualified for Automotive Applications good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers APPLICATIONS and DSPs. n Cycle-by-cycle current limit, frequency foldback and ther- Automotive n mal shutdown provide protection against shorted out- DSP Power Supplies n puts, and soft-start eliminates input current surge during Wall Transformer Regulation n start-up. The low current (<2μA) shutdown mode enables DSL and Cable Modems n easy power management in battery-powered systems. PCI Express All registered trademarks and trademarks are the property of their respective owners. TYPICAL APPLICATION3.3V and 5V Dual Output Step-Down Converter with Output Sequencing V Efficiency IN 5.6V TO 36V ON OFF 95 4.7µF VIN = 12V VIN1 VIN2 SHDN OUT2 BOOST1 5V 90 VOUT2 = 5V BOOST2 1.4A 6.8µH 0.22µF 0.22µF OUT1 10µH V 85 OUT1 = 3.3V 3.3V SW1 SW2 1.4A LT3508 80 35.7k 56.2k FB1 FB2 EFFICIENCY (%) 75 VC1 VC2 11.5k 51k TRACK/SS1 PG1 43k 10.7k 10µF 70 TRACK/SS2 PG2 22µF 150pF GND RT/SYNC 100k 65 0 0.5 1 1.5 1nF 52.3k 100pF LOAD CURRENT (A) 3508 TA01b POWER fSW = 700kHz 3508 TA01a GOOD Rev. E Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Related Parts
