POWER LOSS (W) LT3690 36V, 4A, 1.5MHz Synchronous Step-Down Switching Regulator with 70A Quiescent Current FEATURES DESCRIPTION n Wide Input Range: The LT 3690 is an adjustable frequency monolithic buck n Operation from 3.9V to 36V switching regulator that accepts input voltages up to 36V. n Overvoltage Lockout Protects Circuits A high efficiency 90m switch is included on the device Through 60V Transients along with the boost diode and the necessary oscillator, n 4A Maximum Output Current control, and logic circuitry. The internal synchronous n Integrated 30m N-Channel Synchronous Switch power switch of 30m increases efficiency and eliminates n Low Ripple (<15mV ) Burst Mode Operation: the need for an external Schottky catch diode. Current P-P I = 70A at 12V to 3.3V mode topology is used for fast transient response and Q IN OUT n Programmable Input Undervoltage Lockout good loop stability. Shutdown reduces input supply cur- n 0.8V Feedback Reference Voltage rent to less than 1A. The low ripple Burst Mode main- n Output Voltage: 0.8V to 20V tains high efficiency at low output currents while keeping n Programmable and Synchronizable Oscillator output ripple below 15mV in typical applications. (170kHz to 1.5MHz) The LT3690 features robust operation and is easily config- n Soft-Startup and Output Voltage Tracking urable. Using a resistor divider on the UVLO pin provides n Short-Circuit Robust a programmable undervoltage lockout. A power good n Power Good Flag flag signals when V reaches 90% of the programmed OUT n Small Thermally Enhanced 4mm 6mm QFN Package output voltage. Protection circuitry senses the current in the power switches to protect the LT3690 against APPLICATIONS short-circuit conditions. Frequency foldback and thermal n Automotive Systems shutdown provide additional protection. The LT3690 is n Industrial Supplies available in a 4mm 6mm QFN package with exposed n Distributed Supply Regulation pads for low thermal resistance. All registered trademarks and trademarks are the property of their respective owners. TYPICAL APPLICATION 3.3V Step-Down Converter Efficiency and Power Loss V IN 100 2.5 0.68F 4.5V TO 36V V = 5V OUT V 10F EN BST IN 90 2.0 3.3H 3.3V V = 3.3V OUT UVLO SW 4A LT3690 80 1.5 SS BIAS V = 5V OUT V PG C 70 1.0 316k V = 3.3V OUT V FB 22k CCINT 0.47F 60 0.5 SYNC RT V = 12V IN 100F GND L = 4.7H 680pF 32.4k 102k = 600kHz 50 0 = 600kHz 0 0.5 1 1.5 2 2.5 3 3.5 4 3690 TA01a LOAD CURRENT (A) 3690 TA01b Rev. C 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LT3690 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) EN, UVLO, V Voltage (Note 2) ................................60V TOP VIEW IN BST Voltage .............................................................55V SW 1 26 SW BST Voltage Above SW Voltage ...............................30V SW 2 25 SW BIAS, PG Voltage ...................................................30V 27 SW SW SW 3 24 FB, RT, SS, SYNC, V , V Voltage ......................6V C CCINT SW 4 23 SW Operating Junction Temperature Range (Notes 3 and 4) SYNC 5 22 BST LT3690E ........................................... 40C to 125C GND GND 6 21 LT3690I ............................................ 40C to 125C RT 7 20 V CCINT LT3690H ........................................... 40C to 150C 28 V 8 GND 19 BIAS C LT3690MP ........................................ 55C to 150C FB PG 9 18 Storage Temperature Range ................. 65C to 150C GND 10 17 EN UFE PACKAGE 26-LEAD (4mm 6mm) PLASTIC QFN = 40C/W, = 2.7C/W JA JC EXPOSED PAD (PIN 27) IS SW, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 28) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3690EUFE PBF LT3690EUFE TRPBF 3690 26-Lead (4mm 6mm) Plastic QFN 40C to 125C LT3690IUFE PBF LT3690IUFE TRPBF 3690 26-Lead (4mm 6mm) Plastic QFN 40C to 125C LT3690HUFE PBF LT3690HUFE TRPBF 3690 26-Lead (4mm 6mm) Plastic QFN 40C to 150C LT3690MPUFE PBF LT3690MPUFE TRPBF 3690 26-Lead (4mm 6mm) Plastic QFN 55C to 150C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with TRMPBF suffix. Rev. C 2 For more information www.analog.com SS 11 UVLO 12 V 13 IN V 14 IN V 15 IN GND 16