LTC3375 8-Channel Programmable, Parallelable 1A Buck DC/DCs Fea T Descrip T n 8-Channel Independent Step-Down DC/DCs The LTC 3375 is a digitally programmable high efficiency n Master-Slave Configurable for Up to 4A Per Output multioutput power supply IC. The DC/DCs consist of eight Channel with a Single Inductor synchronous buck converters (I up to 1A each) all OUT n Independent V Supply for Each DC/DC powered from independent 2.25V to 5.5V input supplies. IN (2.25V to 5.5V) DC/DC enables, output voltages, operating modes, and n All DC/DCs Have 0.425V to V Output Voltage Range IN 2 phasing may all be independently programmed over I C n Precision Enable Pin Thresholds for Autonomous or used in standalone mode via simple I/O with power-up 2 Sequencing (or I C Control) defaults. The DC/DCs may be used independently or in n 1MHz to 3MHz Programmable/Synchronizable parallel to achieve higher output currents of up to 4A per Oscillator Frequency (2MHz Default) output with a shared inductor. Alarm levels for high die 2 n I C Selectable Phasing (90 Steps) Per Channel 2 temperature may also be programmed via I C with a mask- n Programmable Power-On Reset/Watch Dog/ able IRQ output for monitoring DC/DC and system faults. Pushbutton Timing n Pushbutton ON/OFF/RESET control, power-on reset, and Die Temperature Monitor Output n a watchdog timer provide flexible and reliable power-up 48-Lead (7mm 7mm) QFN Package sequencing and system monitoring. The LTC3375 is avail- a T able in a low profile 48-lead 7mm 7mm QFN package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear n General Purpose Multichannel Power Supplies Technology Corporation. All other trademarks are the property of their respective owners. n Industrial/Automotive/Communications Typical a T 8-Channel 1A Multioutput Buck Regulator 4V TO 40V 2.2H V IN1 Buck Efficiency vs Load 0.425V TO V IN1 V SW1 SHNT UP TO 1A 10F 100 ALWAYS-ON V CC LDO FB1 90 MASTER LTC3375 1A BUCK FBV 80 CC 2A BUCK ON 70 3A BUCK V 2.2H IN2 SLAVE 0.425V TO V 4A BUCK KILL IN2 SW2 60 UP TO 1A PB 10F 50 PB FB2 40 EN1 30 Burst Mode OPERATION EN2 MASTER V = 3.3V IN 20 EN3 V = 1.8V OUT EN4 f = 2MHz 10 OSC V 2.2H IN7 SLAVE EN5 L = 2.2H 0.425V TO V IN7 SW7 0 EN6 UP TO 1A 1 10 100 1000 EN7 10F LOAD CURRENT (mA) EN8 FB7 3375 TA01b RST MASTER TEMP WDI V 2.2H WD0 IN8 SLAVE 0.425V TO V IN8 SW8 IRQ UP TO 1A 2 2 10F I C SYNC FB8 RT CT 3375 TA01a 3375fd 1 For more information www.linear.com/3375 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3375 Table o F c T Ts Features ..................................................... 1 Applications Information ................................ 26 Applications ................................................ 1 Buck Switching Regulator Output Voltage and Typical Application ........................................ 1 Feedback Network ..................................................26 Description.................................................. 1 Buck Regulators .....................................................26 Absolute Maximum Ratings .............................. 3 Combined Buck Regulators.....................................26 Order Information .......................................... 3 V Shunt Regulator ...............................................28 CC Pin Configuration .......................................... 3 Input and Output Decoupling Capacitor Selection ..29 Electrical Characteristics ................................. 4 Choosing the C Capacitor ......................................29 T Typical Performance Characteristics ................... 7 Programming the Global Register ...........................29 Pin Functions .............................................. 12 Programming the RST and IRQ Mask Registers .....29 Block Diagram ............................................. 15 Status Byte Read Back ...........................................29 Operation................................................... 16 PCB Considerations ................................................31 Buck Switching Regulators ..................................... 16 Typical Applications ...................................... 32 Buck Regulators with Combined Power Stages ...... 16 Package Description ..................................... 35 Pushbutton Interface .............................................. 17 Typical Application ....................................... 36 Power-Up and Power-Down Via Pushbutton ........... 17 Related Parts .............................................. 36 2 Power-Up and Power-Down Via Enable Pin or I C .. 19 2 I C Interface ...........................................................20 2 I C Bus Speed .........................................................20 2 I C Start and Stop Conditions .................................20 2 I C Byte Format ......................................................20 2 I C Acknowledge ....................................................20 2 I C Slave Address ...................................................21 2 I C Sub-Addressed Writing .....................................22 2 I C Bus Write Operation .........................................22 2 I C Bus Read Operation ..........................................22 Error Condition Reporting Via RST and IRQ Pins ....22 Temperature Monitoring and Overtemperature Protection ...................................23 RESET ALL Functionality ....................................... 24 Programming the Operating Frequency .................. 24 V Shunt Regulator ...............................................25 CC Watchdog Timer .....................................................25 3375fd 2 For more information www.linear.com/3375 en on