LTC3370 4-Channel 8A Configurable Buck DC/DCs Fea T Descrip T n 8 1A Power Stages Configurable as 2, 3, or 4 Output The LTC 3370 is a highly flexible multioutput power Channels supply IC. The device includes four synchronous buck n 8 Unique Output Configurations (1A to 4A Per Channel) converters, configured to share eight 1A power stages, n Independent V Supplies for Each DC/DC each of which is powered from independent 2.25V to IN (2.25V to 5.5V) 5.5V inputs. n Low Total No Load Supply Current: The DC/DCs are assigned to one of eight power configu- n Zero Current In Shutdown (All Channels Off) rations via pin programmable C1-C3 pins. The common n 63A One Channel Active in Burst Mode Operation buck switching frequency may be programmed with an n 18A Per Additional Channel external resistor, synchronized to an external oscillator, n Precision Enable Pin Thresholds for Autonomous or set to a default internal 2MHz clock. Sequencing n 1MHz to 3MHz RT Programmable Frequency The operating mode for all DC/DCs may be programmed (2MHz Default) or PLL Synchronization via the PLL/MODE pin for Burst Mode or forced continuous n Temp Monitor Indicates Die Temperature mode operation. A PGOODALL output indicates when all n PGOODALL Pin Indicates All Enabled Bucks Are in enabled DC/DCs are within a specified percentage of their Regulation final output value. n 32-Lead 5mm 5mm QFN Package To reduce input noise, the buck converters are phased in 90 steps. Precision enable pin thresholds facilitate a T reliable power-up sequencing. The LTC3370 is available n General Purpose Multichannel Power Supplies: in a 32-lead 5mm 5mm QFN package. Automotive, Industrial, Distributed Power Systems L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Buck Efficiency vs I LOAD Typical a T 100 90 2.7V TO 5.5V 80 V 70 CC 2.25V TO 5.5V V V 2.25V TO 5.5V INA INE V V 60 2.2H INB INF 2.2H Burst Mode OPERATION V V OUT1 OUT3 V = 3.3V SWA SWE IN 50 1.2V/2A 1.8V/2A V = 1.8V SWB SWF OUT 324k 806k f = 1MHz 40 OSC FB1 FB3 L = 3.3H 30 EN1 EN3 649k 649k 1A BUCK 20 LTC3370 2A BUCK 3A BUCK 10 2.25V TO 5.5V V V 2.5V TO 5.5V INC ING 4A BUCK V V 2.2H IND INH 2.2H 0 V V OUT2 OUT4 1 10 100 1000 4000 SWC SWG 2.5V/2A 1.5V/2A LOAD CURRENT (mA) SWD SWH 715k 665k 3370 TA01b FB2 FB4 EN2 EN4 649k 309k C3 C2 C1 BUCK1 BUCK2 BUCK3 BUCK4 0 0 0 2A 2A 2A 2A PLL/MODE TEMP 0 0 1 3A 1A 2A 2A RT PGOODALL 0 1 0 3A 1A 1A 3A 402k C1 C2 C3 GND 3370 TA01a 0 1 1 4A 1A 1A 2A 1 0 0 3A 2A 3A 1 0 1 4A 2A 2A 1 1 0 4A 1A 3A 1 1 1 4A 4A 3370fb 1 For more information www.linear.com/LTC3370 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3370 Table o F c T Ts Features ............................................................................................................................ 1 Applications ....................................................................................................................... 1 Typical Application ............................................................................................................... 1 Description......................................................................................................................... 1 Absolute Maximum Ratings ..................................................................................................... 3 Order Information ................................................................................................................. 3 Pin Configuration ................................................................................................................. 3 Electrical Characteristics ........................................................................................................ 4 Typical Performance Characteristics .......................................................................................... 6 Pin Functions .....................................................................................................................12 Block Diagram ....................................................................................................................14 Operation..........................................................................................................................15 Buck Switching Regulators ....................................................................................................................................15 Buck Regulators with Combined Power Stages .....................................................................................................15 Power Failure Reporting Via PGOODALL Pin .........................................................................................................16 Temperature Monitoring and Overtemperature Protection .....................................................................................16 Programming the Operating Frequency .................................................................................................................16 Applications Information .......................................................................................................17 Buck Switching Regulator Output Voltage and Feedback Network ........................................................................17 Buck Regulators ....................................................................................................................................................17 Combined Buck Power Stages ...............................................................................................................................17 Input and Output Decoupling Capacitor Selection..................................................................................................17 PCB Considerations ...............................................................................................................................................19 Typical Applications .............................................................................................................20 Package Description ............................................................................................................23 Typical Application ..............................................................................................................24 Related Parts .....................................................................................................................24 3370fb 2 For more information www.linear.com/LTC3370 en on