LT3507 Triple Monolithic Step-Down Regulator with LDO Features Description n Wide Input Range: 4V to 36V The LT 3507 is a triple, current mode, DC/DC converter n One 2.4A and Two 1.5A Output Switching with internal power switches and a low dropout regulator. Regulators with Internal Power Switches The switching converters are step-down converters capable n Low Dropout Linear Regulator with External of generating one 2.4A output and two 1.5A outputs. All Transistor three converters are synchronized to a single oscillator. n Antiphase Switching Reduces Ripple The 2.4A output runs with opposite phase to the other two n Independent Run, Tracking/Soft-Start, and Power converters, reducing input ripple current. Each regulator Good Indicators Ease Supply Sequencing has independent shutdown and soft-start circuits, and n Uses Small Inductors and Ceramic Capacitors generates a power good signal when its output is in regu- n Adjustable, 250kHz to 2.5MHz Switching Frequency, lation, easing power supply sequencing and interfacing Synchronizable Over the Full Range with microcontrollers and DSPs. n User Programmable Overvoltage and Undervoltage The switching frequency is set with a single resistor yielding Lockouts a range of 250kHz to 2.5MHz. The high switching frequency n Thermally Enhanced, 38-Lead 5mm 7mm QFN allows the use of small inductors and capacitors resulting Package in a very small triple output supply. The constant switching frequency, combined with low impedance ceramic capaci- a tors, results in low, predictable output ripple. With its wide n DSL and Cable Modems input voltage range of 4V to 36V, the LT3507 regulates n Distributed Power Regulation a broad array of power sources including 5V logic rails, n DSP Power unregulated wall transformers, lead acid batteries and n Automotive distributed power supplies. L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. t ypical a 5V, 3.3V, 2.5V and 1.8V Step-Down Regulator Start-Up WaveformsCoincident Tracking V IN 6V TO 36V 22F V V V IN1 IN2 IN3 BOOST1 BOOST2 V OUT3 0.22F V 4.7H OUT1 1.8V SW1 0.22F 2.4A V OUT2 1V/DIV 18.7k V OUT4 10H V OUT2 100F V SW2 FB1 3.3V OUT1 1.3A 680pF 15k 18.7k V C1 35.7k 22F LT3507 V OUT2 FB2 BOOST3 0.22F 3507 TA01b V 15H OUT3 1ms/DIV 11.5k 5V 1000pF SW3 16.2k 1.5A V C2 53.6k 22F FB3 BIAS 680pF 10.2k 24.3k DRIVE V C3 V 24.3k OUT4 2.5V FB4 R /SYNC T 0.2A 107k 11.5k 2.2F GND f = 450kHz SW 3507 TA01a 3507fb For more information www.linear.com/LT3507 1 pplication pplicationsLT3507 a bsolute Maxi Mu M r Gs p Fi G (Note 1) V Pins ...................................................... 0.3V to 36V TOP VIEW IN BOOST Pins ..............................................................55V BOOST Above SW .....................................................25V 38 37 36 35 34 33 32 PGOOD Pins ..............................................................36V BOOST1 1 31 V IN2 BIAS Pin ....................................................................16V V 2 30 V IN1 IN2 TRK/SS, V , FB, R /SYNC Pins ...................................6V C T V 3 29 SW2 IN1 RUN, OVLO, UVLO Pins ........................................... V V 4 28 SW2 IN1 INSW OVLO 5 27 BOOST2 DRIVE Pin ...................................................................5V UVLO TRK/SS4 6 26 Operating Junction Temperature Range (Notes 2, 5) 39 V 7 25 FB4 C1 LT3507E, LT3507I .............................. 40C to 125C TRK/SS1 8 24 DRIVE LT3507H ............................................ 40C to 150C FB1 9 23 V C2 Storage Temperature Range .................. 65C to 150C PGOOD1 10 22 FB2 PGOOD2 11 21 TRK/SS2 20 PGOOD3 12 FB3 13 14 15 16 17 18 19 UHF PACKAGE 38-LEAD (5mm 7mm) PLASTIC QFN = 34C/W JA EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB Der in F M LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3507EUHF PBF LT3507EUHF TRPBF 3507 38-Lead (5mm 7mm) Plastic QFN 40C to 125C LT3507IUHF PBF LT3507IUHF TRPBF 3507 38-Lead (5mm 7mm) Plastic QFN 40C to 125C LT3507HUHF PBF LT3507HUHF TRPBF 3507 38-Lead (5mm 7mm) Plastic QFN 40C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: