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LTC3370IUH#TRPBF

LTC3370IUH#TRPBF

  • 厂商:

    LINEAR(凌力尔特)

  • 封装:

    WFQFN32_EP

  • 描述:

    IC REG BUCK ADJ 2A QD SYNC 32QFN

  • 数据手册
  • 价格&库存
LTC3370IUH#TRPBF 数据手册
LTC3370 4-Channel 8A Configurable Buck DC/DCs Features Description 8 × 1A Power Stages Configurable as 2, 3, or 4 Output Channels n 8 Unique Output Configurations (1A to 4A Per Channel) n Independent V Supplies for Each DC/DC IN (2.25V to 5.5V) n Low Total No Load Supply Current: n Zero Current In Shutdown (All Channels Off) n 63µA One Channel Active in Burst Mode® Operation n 18µA Per Additional Channel n Precision Enable Pin Thresholds for Autonomous Sequencing n 1MHz to 3MHz RT Programmable Frequency (2MHz Default) or PLL Synchronization n Temp Monitor Indicates Die Temperature n PGOODALL Pin Indicates All Enabled Bucks Are in Regulation n 32-Lead 5mm × 5mm QFN Package The LTC®3370 is a highly flexible multioutput power supply IC. The device includes four synchronous buck converters, configured to share eight 1A power stages, each of which is powered from independent 2.25V to 5.5V inputs. n Applications General Purpose Multichannel Power Supplies: Automotive, Industrial, Distributed Power Systems n The DC/DCs are assigned to one of eight power configurations via pin programmable C1-C3 pins. The common buck switching frequency may be programmed with an external resistor, synchronized to an external oscillator, or set to a default internal 2MHz clock. The operating mode for all DC/DCs may be programmed via the PLL/MODE pin for Burst Mode or forced continuous mode operation. A PGOODALL output indicates when all enabled DC/DCs are within a specified percentage of their final output value. To reduce input noise, the buck converters are phased in 90° steps. Precision enable pin thresholds facilitate reliable power-up sequencing. The LTC3370 is available in a 32-lead 5mm × 5mm QFN package. 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. Typical Application 90 2.7V TO 5.5V 80 VINE VINF 2.25V TO 5.5V 2.2µH 324k SWA SWB SWE SWF 806k 649k FB1 EN1 FB3 EN3 649k EFFICIENCY (%) VOUT1 1.2V/2A VINA VINB 2.25V TO 5.5V 2.2µH VCC VOUT3 1.8V/2A VOUT2 1.5V/2A 2.2µH 715k VINC VIND VING VINH SWC SWD SWG SWH FB2 EN2 649k 665k FB4 EN4 309k PLL/MODE TEMP RT PGOODALL 402k C1 C2 C3 GND 3370 TA01a 60 Burst Mode OPERATION VIN = 3.3V VOUT = 1.8V f OSC = 1MHz L = 3.3µH 50 40 30 1A BUCK 2A BUCK 3A BUCK 4A BUCK 10 2.5V TO 5.5V 2.2µH 70 20 LTC3370 2.25V TO 5.5V Buck Efficiency vs ILOAD 100 0 VOUT4 2.5V/2A 1 10 100 1000 LOAD CURRENT (mA) 4000 3370 TA01b C3 C2 C1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 BUCK1 BUCK2 BUCK3 BUCK4 2A 3A 3A 4A 3A 4A 4A 4A 2A 1A 1A 1A 2A – – – 2A 2A 1A 1A – 2A 1A – 2A 2A 3A 2A 3A 2A 3A 4A 3370fb For more information www.linear.com/LTC3370 1 LTC3370 Table of Contents 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 2 3370fb For more information www.linear.com/LTC3370 LTC3370 FB4 EN4 RT PLL/MODE VCC TOP VIEW TEMP VINA-H, FB1-4, EN1-4, VCC, PGOODALL, RT, PLL/MODE, C1-3.................................... –0.3V to 6V TEMP................... –0.3V to Lesser of (VCC + 0.3V) or 6V IPGOODALL..................................................................5mA Operating Junction Temperature Range (Notes 2, 3)............................................. –40°C to 150°C Storage Temperature Range................... –65°C to 150°C Pin Configuration EN1 (Note 1) FB1 Absolute Maximum Ratings 32 31 30 29 28 27 26 25 VINA 1 24 VINH SWA 2 23 SWH SWB 3 22 SWG VINB 4 21 VING 33 GND VINC 5 20 VINF SWC 6 19 SWF SWD 7 18 SWE VIND 8 17 VINE FB3 EN3 PGOODALL C3 C2 C1 FB2 EN2 9 10 11 12 13 14 15 16 UH PACKAGE 32-LEAD (5mm × 5mm) PLASTIC QFN TJMAX = 150°C, θJA = 34°C/W, θJC = 3°C/W EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB Order Information (http://www.linear.com/product/LTC3370#orderinfo) LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3370EUH#PBF LTC3370EUH#TRPBF 3370 32-Lead (5mm × 5mm) Plastic QFN –40°C to 125°C LTC3370IUH#PBF LTC3370IUH#TRPBF 3370 32-Lead (5mm × 5mm) Plastic QFN –40°C to 125°C LTC3370HUH#PBF LTC3370HUH#TRPBF 3370 32-Lead (5mm × 5mm) Plastic QFN –40°C to 150°C 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: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. 3370fb For more information www.linear.com/LTC3370 3 LTC3370 Electrical Characteristics The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = VINA-H = 3.3V, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN VCC VCC Voltage Range VCC(UVLO) Undervoltage Threshold on VCC VCC Voltage Falling VCC Voltage Rising IVCC(ALLOFF) VCC Input Supply Current All Switching Regulators in Shutdown IVCC VCC Input Supply Current One Buck Active PLL/MODE = 0V, RT = 400k, VFB(BUCK) = 0.85V PLL/MODE = 2MHz fOSC Internal Oscillator Frequency VRT = VCC, PLL/MODE = 0V VRT = VCC, PLL/MODE = 0V RT = 400k, PLL/MODE = 0V l l 1.8 1.75 1.8 l 2.7 l l 2.325 2.425 fPLL/MODE Synchronization Frequency tLOW, tHIGH > 40ns l 1 VPLL/MODE PLL/MODE Level High PLL/MODE Level Low For Synchronization For Synchronization l l 1.2 VRT RT Servo Voltage RT = 400k l 780 180 TYP MAX UNITS 5.5 V 2.45 2.55 2.575 2.675 V V 0 2.5 µA 45 170 70 250 µA µA 2 2 2 2.2 2.25 2.2 MHz MHz MHz 3 MHz 0.4 V V 800 820 mV 220 260 mV Temp Monitor VTEMP(ROOM) TEMP Voltage at 25°C ΔVTEMP/°C VTEMP Slope OT Overtemperature Shutdown 170 °C OT Hyst Overtemperature Hysteresis 10 °C 7 mV/°C 1A Buck Regulators VIN Buck Input Voltage Range VOUT Buck Output Voltage Range VIN(UVLO) Undervoltage Threshold on VIN VIN Voltage Falling VIN Voltage Rising IVIN Burst Mode Operation Input Current Forced Continuous Mode Operation Input Current Shutdown Input Current VFB = 0.85V (Note 4) ISW(BUCK) = 0µA, FB = 0V IFWD PMOS Current Limit (Note 5) 1.9 2.3 2.7 A VFB1 Feedback Regulation Voltage for Buck 1 l 792 800 808 mV VFB Feedback Regulation Voltage for Bucks 2-4 l 780 800 820 mV IFB Feedback Leakage Current VFB = 0.85V 50 nA l 2.25 l VFB l l 1.95 2.05 5.5 V VIN V 2.05 2.15 2.15 2.25 V V 18 400 30 600 µA µA 0 2.5 µA –50 DMAX Maximum Duty Cycle VFB = 0V RPMOS PMOS On-Resistance ISW = 100mA RNMOS NMOS On-Resistance ISW = –100mA ILEAKP PMOS Leakage Current EN = 0 –2 2 µA ILEAKN NMOS Leakage Current EN = 0 –2 2 µA tSS Soft-Start Time VPGOOD(FALL) Falling PGOOD Threshold for Buck 1 4 PGOOD Hysteresis for Bucks 1 to 4 100 % 300 mΩ 240 mΩ 1 % of Regulated VFB Falling PGOOD Threshold for Bucks 2 to 4 % of Regulated VFB VPGOOD(HYS) l % of Regulated VFB ms 96.8 98 99.2 % 93 95 97 % 0.3 % 3370fb For more information www.linear.com/LTC3370 LTC3370 Electrical Characteristics The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = VINA-H = 3.3V, unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Buck Regulators Combined IFWD2 PMOS Current Limit 2 Buck Power Stages Combined (Note 5) 4.6 A IFWD3 PMOS Current Limit 3 Buck Power Stages Combined (Note 5) 6.9 A IFWD4 PMOS Current Limit 4 Buck Power Stages Combined (Note 5) 9.2 A Interface Logic Pins (PGOODALL, PLL/MODE, CT, C1, C2, C3) IOH Output High Leakage Current PGOODALL 5.5V at Pin VOL Output Low Voltage PGOODALL 3mA into Pin VIL C1, C2, C3 Input Low Threshold l VIH PLL/MODE, CT, C1, C2, C3 Input High Threshold l VIL PLL/MODE Input Low Threshold l 0.1 1 µA 0.4 V 0.4 V VCC – 0.4 V VCC – 1.2 V Interface Logic Pins (EN1, EN2, EN3, EN4) VHI(ALLOFF) Enable Rising Threshold All Regulators Disabled l 730 1200 mV VHI Enable Rising Threshold At Least One Regulator Enabled l 400 420 mV VLO Enable Falling Threshold IEN Enable Pin Leakage Current 340 EN = 3.3V Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3370 is tested under pulsed load conditions such that TJ ≈ TA. The LTC3370E is guaranteed to meet specifications from 0°C to 85°C junction temperature. Specifications over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3370I is guaranteed over the –40°C to 125°C operating junction temperature range. The LTC3370H is guaranteed over the –40°C to 150°C operating junction temperature range. High junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125°C. Note that the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors. The junction temperature (TJ in °C) is calculated from the ambient temperature (TA in °C) and power dissipation (PD in Watts) according to the formula: TJ = TA + (PD • θJA) where θJA (in °C/W) is the package thermal impedance. 375 mV 1 µA Note 3: The LTC3370 includes overtemperature protection which protects the device during momentary overload conditions. Junction temperatures will exceed 150°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 4: Static current, switches not switching. Actual current may be higher due to gate charge losses at the switching frequency. Note 5: The current limit features of this part are intended to protect the IC from short term or intermittent fault conditions. Continuous operation above the maximum specified pin current rating may result in device degradation over time. 3370fb For more information www.linear.com/LTC3370 5 LTC3370 Typical Performance Characteristics 3000 90 2500 EFFICIENCY (%) 70 Burst Mode OPERATION VIN = 3.3V VOUT = 1.8V fOSC = 2MHz L = 2.2µH 40 30 10 1 2000 1000 500 0 125 2.25 100 1 5 35 65 95 TEMPERATURE (°C) 125 155 3370 G03 VCC Supply Current vs Temperature 400 AT LEAST ONE BUCK ENABLED PLL/MODE = 0V FB = 850mV AT LEAST ONE BUCK ENABLED 360 PLL/MODE = 2MHz 320 VIN FALLING 75 240 IVCC (µA) IVCC (µA) UV THRESHOLD (V) 2.10 50 200 160 120 25 1.90 –55 –25 5 35 65 95 TEMPERATURE (°C) 125 0 –55 155 –25 3370 G04 125 0 –55 155 2.20 1.95 VCC = 2.7V VCC = 3.3V VCC = 5.5V 2.10 2.15 2.10 2.00 2.00 1.85 1.85 155 3371 G07 1.80 –55 RT = 400k 1.95 1.95 1.85 125 VRT = VCC 2.05 2.05 1.90 5 35 65 95 TEMPERATURE (°C) 155 Oscillator Frequency vs VCC 1.90 –25 125 2.20 1.90 1.80 –55 5 35 65 95 TEMPERATURE (°C) fOSC (MHz) 2.00 VRT = VCC 2.15 f OSC (MHz) 2.05 –25 3370 G06 Default Oscillator Frequency vs Temperature VCC = 2.7V VCC = 3.3V VCC = 5.5V 2.10 5 35 65 95 TEMPERATURE (°C) VCC = 2.7V VCC = 3.3V VCC = 5.5V 40 3370 G05 RT Programmed Oscillator Frequency vs Temperature RT = 400k 80 VCC = 2.7V VCC = 3.3V VCC = 5.5V 1.95 6 –25 280 2.00 fOSC (MHz) 2.30 –55 10 100 1000 LOAD CURRENT (mA) VIN RISING 2.05 VCC FALLING 2.45 VCC Supply Current vs Temperature 2.30 2.15 2.50 3370 G02 Buck VIN Undervoltage Threshold vs Temperature 2.15 VCC RISING 2.55 2.35 3370 G01 2.20 2.60 1A BUCK 2A BUCK 3A BUCK 4A BUCK 1500 10 100 1000 LOAD CURRENT (mA) 2.20 2.65 2.40 1A BUCK 2A BUCK 3A BUCK 4A BUCK 20 0 POWER LOSS (mW) 80 2.70 Burst Mode OPERATION VIN = 3.3V VOUT = 1.8V fOSC = 2MHz L = 2.2µH UV THRESHOLD (V) 100 50 VCC Undervoltage Threshold vs Temperature Buck Power Loss vs ILOAD Buck Efficiency vs ILOAD 60 TA = 25°C, unless otherwise noted. –25 5 35 65 95 TEMPERATURE (°C) 125 155 3370 G08 1.80 2.7 3.1 3.5 3.9 4.3 VCC (V) 4.7 5.1 5.5 3370 G09 3370fb For more information www.linear.com/LTC3370 LTC3370 Typical Performance Characteristics VTEMP vs Temperature Oscillator Frequency vs RT ILOAD = 0mA 1200 VCC = 3.3V 3.0 1000 1.5 600 1.0 200 0.5 0 0 250 300 350 400 450 500 550 600 650 700 750 800 RT (kΩ) 800 ACTUAL VTEMP 400 –200 –55 50 EN RISING 385 EN FALLING 375 –25 5 35 65 95 TEMPERATURE (°C) 125 155 125 20 0 –55 155 –25 VIN = 2.25V VIN = 3.3V VIN = 5.5V –25 1.88 2.6 FORCED CONTINUOUS MODE 1.86 I LOAD = 0mA 5 35 65 95 TEMPERATURE (°C) 125 350 300 250 200 150 VIN = 2.25V VIN = 3.3V VIN = 5.5V 100 0 –55 155 –25 550 VIN = 3.3V RDS(ON) (mΩ) IFWD (A) 2.2 1.76 VIN = 2.25V VIN = 3.3V VIN = 5.5V 1.74 –25 5 35 65 95 TEMPERATURE (°C) 125 155 3370 G16 155 VIN = 2.25V VIN = 3.3V VIN = 5.5V 450 2.3 125 PMOS RDS(ON) vs Temperature 500 2.4 5 35 65 95 TEMPERATURE (°C) 3370 G15 1.84 1.78 155 400 50 2.5 1.82 125 FORCED CONTINUOUS MODE 500 FB = 0V 450 PMOS Current Limit vs Temperature 1.80 5 35 65 95 TEMPERATURE (°C) 3370 G12 3370 G14 VOUT vs Temperature VOUT (V) EN FALLING 550 3370 G13 1.72 –55 500 Buck VIN Supply Current vs Temperature 30 370 5 35 65 95 TEMPERATURE (°C) 550 350 –55 Burst Mode OPERATION FB = 850mV 10 –25 600 400 IDEAL VTEMP 40 IVIN_BURST (µA) EN THRESHOLD (mV) 400 365 –55 650 Buck VIN Supply Current vs Temperature 405 380 700 3370 G11 Enable Pin Precision Threshold vs Temperature 390 EN RISING 750 450 3370 G10 395 ALL REGULATORS DISABLED VCC = 3.3V 850 800 VTEMP (mV) 2.0 900 EN THRESHOLD (mV) VCC = 3.3V 3.5 2.5 fOSC (MHz) Enable Threshold vs Temperature 1400 IVIN_FORCED_CONTINUOUS (µA) 4.0 TA = 25°C, unless otherwise noted. 400 350 300 250 2.1 2.0 –55 200 –25 5 35 65 95 TEMPERATURE (°C) 125 155 3370 G17 150 –55 –25 5 35 65 95 TEMPERATURE (°C) 125 155 3370 G18 3370fb For more information www.linear.com/LTC3370 7 LTC3370 Typical Performance Characteristics 100 EFFICIENCY (%) RDS(ON) (mΩ) 350 300 250 80 Burst Mode OPERATION 900 VOUT = 1.2V fOSC = 2MHz 800 L = 2.2µH 70 700 60 VIN = 2.25V VIN = 3.3V VIN = 5.5V VIN = 2.25V VIN = 3.3V VIN = 5.5V 50 40 30 20 200 10 150 –55 –25 5 35 65 95 TEMPERATURE (°C) 125 0 155 1000 Burst Mode OPERATION 90 1 70 700 30 20 FORCED CONTINUOUS MODE 10 0 1 POWER LOSS (mW) EFFICIENCY (%) 40 600 VIN = 3.3V 400 300 0 100 1000 VIN = 5.5V 400 200 1 100 0 1 10 100 LOAD CURRENT (mA) 3370 G25 8 VIN = 2.7V VIN = 3.3V VIN = 5.5V VIN = 2.7V VIN = 3.3V VIN = 5.5V 50 40 30 FORCED CONTINUOUS MODE 10 100 LOAD CURRENT (mA) 0 1000 1 VOUT = 2.5V fOSC = 2MHz L = 2.2µH 10 100 LOAD CURRENT (mA) 3370 G24 1A Buck Power Loss vs ILOAD, VOUT = 3.3V Burst Mode OPERATION 900 VOUT = 3.3V fOSC = 2MHz 800 L = 2.2µH Burst Mode OPERATION 70 60 VIN = 4.2V VIN = 5.5V VIN = 4.2V VIN = 5.5V 50 40 30 0 1000 1000 FORCED CONTINUOUS MODE 10 1000 60 1A Buck Efficiency vs ILOAD, VOUT = 3.3V 20 VIN = 5.5V Burst Mode OPERATION 70 10 80 VIN = 2.7V 300 1A Buck Efficiency vs ILOAD, VOUT = 2.5V 20 90 EFFICIENCY (%) POWER LOSS (mW) Burst Mode OPERATION 900 VOUT = 2.5V fOSC = 2MHz 800 L = 2.2µH VIN = 3.3V 1000 3370 G23 1A Buck Power Loss vs ILOAD, VOUT = 2.5V 600 10 100 LOAD CURRENT (mA) 80 100 1000 700 1 90 3370 G22 500 100 VIN = 2.25V 500 200 VOUT = 1.8V fOSC = 2MHz L = 2.2µH 10 100 LOAD CURRENT (mA) VIN = 5.5V 3370 G21 EFFICIENCY (%) 80 VIN = 2.25V VIN = 3.3V VIN = 5.5V VIN = 2.25V VIN = 3.3V VIN = 5.5V 300 0 1000 90 50 VIN = 3.3V 400 100 1A Buck Power Loss vs ILOAD, VOUT = 1.8V Burst Mode OPERATION 900 VOUT = 1.8V fOSC = 2MHz 800 L = 2.2µH 60 500 3370 G20 1A Buck Efficiency vs ILOAD, VOUT = 1.8V Burst Mode OPERATION VIN = 2.25V 600 200 VOUT = 1.2V FORCED CONTINUOUS fOSC = 2MHz L = 2.2µH MODE 10 100 1000 LOAD CURRENT (mA) 3370 G19 100 POWER LOSS (mW) VIN = 2.25V VIN = 3.3V VIN = 5.5V 400 1A Buck Power Loss vs ILOAD, VOUT = 1.2V 1A Buck Efficiency vs ILOAD, VOUT = 1.2V NMOS RDS(ON) vs Temperature POWER LOSS (mW) 450 TA = 25°C, unless otherwise noted. 1 VOUT = 3.3V fOSC = 2MHz L = 2.2µH 10 100 LOAD CURRENT (mA) 1000 3370 G26 700 600 500 VIN = 5.5V 400 300 VIN = 4.2V 200 100 0 1 10 100 LOAD CURRENT (mA) 1000 3370 G27 3370fb For more information www.linear.com/LTC3370 LTC3370 Typical Performance Characteristics 3A Buck Efficiency vs ILOAD, VOUT = 1.8V 2A Buck Efficiency vs ILOAD, VOUT = 2.5V 2A Buck Efficiency vs ILOAD, VOUT = 1.8V 100 90 90 90 80 80 70 Burst Mode OPERATION 60 70 50 40 30 20 0 1 10 100 LOAD CURRENT (mA) 60 VIN = 2.7V VIN = 3.3V VIN = 5.5V VIN = 2.7V VIN = 3.3V VIN = 5.5V 50 40 30 20 VOUT = 1.8V FORCED CONTINUOUS fOSC = 2MHz L = 2.2µH MODE 10 80 Burst Mode OPERATION 0 1 10 100 LOAD CURRENT (mA) 30 0 100 90 90 90 80 80 60 VIN = 2.7V VIN = 3.3V VIN = 5.5V VIN = 2.7V VIN = 3.3V VIN = 5.5V 50 40 30 FORCED CONTINUOUS MODE 10 0 1 FORCED CONTINUOUS MODE 60 50 40 30 10 0 1000 VOUT = 1.8V fOSC = 2MHz L = 2.2µH VIN = 2.25V VIN = 3.3V VIN = 5.5V VIN = 2.25V VIN = 3.3V VIN = 5.5V 20 VOUT = 2.5V fOSC = 2MHz L = 2.2µH 10 100 LOAD CURRENT (mA) 1 90 90 80 80 60 FORCED CONTINUOUS MODE 50 40 fOSC = 1MHz, L = 3.3µH fOSC = 2MHz, L = 2.2µH fOSC = 3MHz, L = 1µH fOSC = 1MHz, L = 3.3µH fOSC = 2MHz, L = 2.2µH fOSC = 3MHz, L = 1µH 30 20 10 0 1 10 100 LOAD CURRENT (mA) 1000 3370 G34 70 50 10 100 LOAD CURRENT (mA) 100 1000 VIN = 3.3V 90 VIN = 3.3V 80 VIN = 5.5V 30 3370 G35 VIN = 2.25V 60 50 40 30 10 3 VIN = 5.5V 70 20 VOUT = 1.8V ILOAD = 100mA L = 3.3µH 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 FREQUENCY (MHz) 1 3370 G33 VIN = 2.25V 40 0 VIN = 2.7V VIN = 3.3V VIN = 5.5V VIN = 2.7V VIN = 3.3V VIN = 5.5V 30 1A Buck Efficiency vs Frequency (Forced Continuous Mode) 50 10 VOUT = 2.5V fOSC = 2MHz L = 2.2µH 40 0 60 20 FORCED CONTINUOUS MODE 10 EFFICIENCY (%) 100 EFFICIENCY (%) 100 Burst Mode OPERATION 60 1A Buck Efficiency vs Frequency (Forced Continuous Mode) VOUT = 1.8V VIN = 3.3V 1000 4A Buck Efficiency vs ILOAD, VOUT = 2.5V 70 3370 G32 1A Buck Efficiency vs ILOAD (Across Operating Frequency) Burst Mode OPERATION 10 100 LOAD CURRENT (mA) 20 10 100 1000 LOAD CURRENT (mA) 3370 G31 70 1 80 Burst Mode OPERATION 70 EFFICIENCY (%) Burst Mode OPERATION VOUT = 1.8V FORCED CONTINUOUS fOSC = 2MHz L = 2.2µH MODE 3370 G30 4A Buck Efficiency vs ILOAD, VOUT = 1.8V EFFICIENCY (%) EFFICIENCY (%) 40 100 70 VIN = 2.25V VIN = 3.3V VIN = 5.5V VIN = 2.25V VIN = 3.3V VIN = 5.5V 50 3370 G29 3A Buck Efficiency vs ILOAD, VOUT = 2.5V 20 EFFICIENCY (%) 60 10 1000 3370 G28 100 Burst Mode OPERATION 70 20 VOUT = 2.5V FORCED CONTINUOUS fOSC = 2MHz L = 2.2µH MODE 10 1000 EFFICIENCY (%) VIN = 2.25V VIN = 3.3V VIN = 5.5V VIN = 2.25V VIN = 3.3V VIN = 5.5V EFFICIENCY (%) 100 100 EFFICIENCY (%) TA = 25°C, unless otherwise noted. 0 VOUT = 1.8V ILOAD = 200mA L = 3.3µH 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 FREQUENCY (MHz) 3 3370 G36 3370fb For more information www.linear.com/LTC3370 9 LTC3370 Typical Performance Characteristics 1A Buck Efficiency vs Frequency (Forced Continuous Mode) ILOAD = 100mA 90 ILOAD = 500mA ILOAD = 20mA 70 60 50 40 30 1.820 1.816 1.816 1.812 1.812 1.800 1.796 VIN = 2.25V 10 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 FREQUENCY (MHz) 1.780 3 1 VIN = 3.3V 1.800 VIN = 2.25V 1.796 1.788 fOSC = 2MHz L = 2.2µH 1.784 VIN = 5.5V 1.804 1.792 DROPOUT 1.788 VOUT = 1.8V VIN = 3.3V L = 3.3µH 1.808 VIN = 3.3V VIN = 5.5V 1.804 1.792 20 0 1.820 1.808 VOUT (V) EFFICIENCY (%) 80 4A Buck Regulator Load Regulation (Forced Continuous Mode) 1A Buck Regulator Load Regulation (Forced Continuous Mode) VOUT (V) 100 TA = 25°C, unless otherwise noted. fOSC = 2MHz L = 2.2µH 1.784 10 100 LOAD CURRENT (mA) 3370 G37 1000 1.780 1 DROPOUT 10 100 1000 LOAD CURRENT (mA) 3370 G39 3370 G38 1A Buck Regulator Line Regulation (Forced Continuous Mode) 1A Buck Regulator No-Load Start-Up Transient (Forced Continuous Mode) 1A Buck Regulator No-Load Start-Up Transient(Burst Mode Operation) 1.820 VIN = 3.3V VOUT = 1.8V 1.815 VIN = 3.3V VOUT = 1.8V VOUT (V) 1.810 1.805 ILOAD = 100mA 1.800 ILOAD = 500mA 1.795 VOUT 500mV/DIV VOUT 500mV/DIV INDUCTOR CURRENT 500mA/DIV INDUCTOR CURRENT 500mA/DIV EN 2V/DIV EN 2V/DIV 1.790 1.785 200µs/DIV fOSC = 2MHz L = 2.2µH 1.780 2.25 2.75 3.25 3.75 4.25 VIN (V) 4.75 3370 G41 200µs/DIV 3370 G42 5.25 3370 G40 4A Buck Regulator No-Load Start-Up Transient (Burst Mode Operation) 1A Buck Regulator Transient Response (Burst Mode Operation) 4A Buck Regulator No-Load Start-Up Transient (Forced Continuous Mode) VIN = 3.3V VOUT = 1.8V VIN = 3.3V VOUT = 1.8V VOUT 100mV/DIV AC-COUPLED VOUT 500mV/DIV VOUT 500mV/DIV INDUCTOR CURRENT 500mA/DIV INDUCTOR CURRENT 500mA/DIV INDUCTOR CURRENT 200mA/DIV EN 2V/DIV EN 2V/DIV 0mA 200µs/DIV 3370 G43 200µs/DIV 3370 G44 50µs/DIV 3370 G45 LOAD STEP = 100mA TO 700mA VIN = 3.3V VOUT = 1.8V 10 3370fb For more information www.linear.com/LTC3370 LTC3370 Typical Performance Characteristics 1A Buck Regulator Transient Response (Forced Continuous Mode) TA = 25°C, unless otherwise noted. 4A Buck Regulator Transient Response (Forced Continuous Mode) 4A Buck Regulator Transient Response (Burst Mode Operation) VOUT 100mV/DIV AC-COUPLED VOUT 100mV/DIV AC-COUPLED VOUT 100mV/DIV AC-COUPLED INDUCTOR CURRENT 200mA/DIV INDUCTOR CURRENT 1A/DIV INDUCTOR CURRENT 1A/DIV 0mA 0mA 0mA 50µs/DIV LOAD STEP = 100mA TO 700mA VIN = 3.3V VOUT = 1.8V 3370 G46 50µs/DIV 3370 G47 LOAD STEP = 400mA TO 2.8A VIN = 3.3V VOUT = 1.8V 50µs/DIV 3370 G48 LOAD STEP = 400mA TO 2.8A VIN = 3.3V VOUT = 1.8V Pin Functions VINA (Pin 1): Power Stage A Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. SWA (Pin 2): Power Stage A Switch Node. External inductor connects to this pin. SWB (Pin 3): Power Stage B Switch Node. External inductor connects to this pin. VINB (Pin 4): Power Stage B Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. VINC (Pin 5): Power Stage C Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. SWC (Pin 6): Power Stage C Switch Node. External inductor connects to this pin. SWD (Pin 7): Power Stage D Switch Node. External inductor connects to this pin. VIND (Pin 8): Power Stage D Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. FB2 (Pin 9): Buck Regulator 2 Feedback Pin. Receives feedback by a resistor divider connected across the output. In configurations where Buck 2 is not used, FB2 should be tied to ground. EN2 (Pin 10): Buck Regulator 2 Enable Input. Active high. In configurations where Buck 2 is not used, tie EN2 to ground. Do not float. C1 (Pin 11): Configuration Control Input Bit. With C2 and C3, C1 configures the Buck output current power stage combinations. C1 should either be tied to VCC or ground. Do not float. C2 (Pin 12): Configuration Control Input Bit. With C1 and C3, C2 configures the Buck output current power stage combinations. C2 should either be tied to VCC or ground. Do not float. C3 (Pin 13): Configuration Control Input Bit. With C1 and C2, C3 configures the Buck output current power stage combinations. C3 should either be tied to VCC or ground. Do not float. PGOODALL (Pin 14): PGOOD Status Pin (Active Low). Open-drain output. When the regulated output voltage of any enabled switching regulator is below its PGOOD threshold level, this pin is driven LOW. This level is 98% of the programmed output value for Buck 1 and 95% of 3370fb For more information www.linear.com/LTC3370 11 LTC3370 Pin Functions the programmed output value for Bucks 2-4. When all buck regulators are disabled PGOODALL is driven LOW. EN3 (Pin 15): Buck Regulator 3 Enable Input. Active high. In configurations where Buck 3 is not used, tie EN3 to ground. Do not float. RT (Pin 27): Oscillator Frequency Pin. This pin provides two modes of setting the switching frequency. Connecting a resistor from RT to ground sets the switching frequency based on the resistor value. If RT is tied to VCC the internal 2MHz oscillator is used. Do not float. SWF (Pin 19): Power Stage F Switch Node. External inductor connects to this pin. PLL/MODE (Pin 28): Oscillator Synchronization and Buck Mode Select Pin. Driving PLL/MODE with an external clock signal synchronizes all switches to the applied frequency, and the buck converters operate in forced continuous mode. The slope compensation is automatically adapted to the external clock frequency. The absence of an external clock signal enables the frequency programmed by the RT pin. When not synchronizing to an external clock this input determines how the LTC3370 operates at light loads. Pulling this pin to ground selects Burst Mode operation. Tying this pin to VCC invokes forced continuous mode operation. Do not float. VINF (Pin 20): Power Stage F Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. VCC (Pin 29): Internal Bias Supply. Bypass to GND with a 10µF or larger ceramic capacitor. VING (Pin 21): Power Stage G Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. TEMP (Pin 30): Temperature Indication Pin. TEMP outputs a voltage of 220mV (typical) at 25°C. The TEMP voltage increases by 7mV/°C (typical) at higher temperatures giving an external indication of the LTC3370 internal die temperature. FB3 (Pin 16): Buck Regulator 3 Feedback Pin. Receives feedback by a resistor divider connected across the output. In configurations where Buck 3 is not used, FB3 should be tied to ground. VINE (Pin 17): Power Stage E Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. SWE (Pin 18): Power Stage E Switch Node. External inductor connects to this pin. SWG (Pin 22): Power Stage G Switch Node. External inductor connects to this pin. SWH (Pin 23): Power Stage H Switch Node. External inductor connects to this pin. VINH (Pin 24): Power Stage H Input Supply. Bypass to GND with a 10µF or larger ceramic capacitor. FB4 (PIN 25): Buck Regulator 4 Feedback Pin. Receives feedback by a resistor divider connected across the output. EN4 (Pin 26): Buck Regulator 4 Enable Input. Active high. Do not float. 12 EN1 (Pin 31): Buck Regulator 1 Enable Input. Active high. Do not float. FB1 (Pin 32): Buck Regulator 1 Feedback Pin. Receives feedback by a resistor divider connected across the output. GND (Exposed Pad Pin 33): Ground. The exposed pad should be connected to a continuous ground plane on the printed circuit board directly under the LTC3370. 3370fb For more information www.linear.com/LTC3370 LTC3370 Block Diagram 29 VCC BANDGAP OT 27 28 14 RT PLL/MODE 4 REF UVLO UV TEMP MONITOR TEMP CLK OSCILLATOR MODE SD PGOODALL VINA 4 PGOOD PGOOD LOGIC 1A POWER STAGE A SWA VINB SD REF CLK 1A POWER STAGE B MODE 4 32 EN1 FB1 1A POWER STAGE C 9 EN2 FB2 1A POWER STAGE D 16 EN3 FB3 BUCK REGULATOR 2 CONTROL 1A POWER STAGE E 26 25 FB4 1A POWER STAGE F BUCK REGULATOR 3 CONTROL 12 1A POWER STAGE H GND (EXPOSED PAD) C3 C2 SWG VINH CONFIGURATION LINES 11 SWF VING 1A POWER STAGE G BUCK REGULATOR 4 CONTROL C1 SWE VINF VING EN4 SWD VINE VINE 15 SWC VIND BUCK REGULATOR 1 CONTROL VIND 10 SWB VINC VINB 31 30 13 33 C3 C2 C1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 SWH 1 2 4 3 5 6 8 7 17 18 20 19 21 22 24 23 3370 BD BUCK1 BUCK2 BUCK3 BUCK4 2A 3A 3A 4A 3A 4A 4A 4A 2A 1A 1A 1A 2A – – – 2A 2A 1A 1A – 2A 1A – 2A 2A 3A 2A 3A 2A 3A 4A 3370fb For more information www.linear.com/LTC3370 13 LTC3370 Operation Buck Switching Regulators The LTC3370 contains eight monolithic 1A synchronous buck switching channels. These are controlled by up to four current mode regulator controllers. All of the switching regulators are internally compensated and need only external feedback resistors to set the output voltage. The switching regulators offer two operating modes: Burst Mode operation (PLL/MODE = LOW) for higher efficiency at light loads and forced continuous PWM mode (PLL/ MODE = HIGH or switching) for lower noise at light loads. In Burst Mode operation at light loads, the output capacitor is charged to a voltage slightly higher than its regulation point. The regulator then goes into a sleep state, during which time the output capacitor provides the load current. In sleep most of the regulator’s circuitry is powered down, helping conserve input power. When the output capacitor droops below its programmed value, the circuitry is powered on and another burst cycle begins. The sleep time decreases as load current increases. In Burst Mode operation, the regulator bursts at light loads whereas at higher loads it operates at constant frequency PWM mode operation. In forced continuous mode, the oscillator runs continuously and the buck switch currents are allowed to reverse under very light load conditions to maintain regulation. This mode allows the buck to run at a fixed frequency with minimal output ripple. Each buck switching regulator can operate at an independent VIN voltage and has its own FB and EN pin to maximize flexibility. The enable pins have two different enable threshold voltages that depend on the operating state of the LTC3370. With all regulators disabled, the enable pin threshold is set to 730mV (typical). Once any regulator is enabled, the enable pin thresholds of the remaining regulators are set to a bandgap-based 400mV and the EN pins are each monitored by a precision comparator. This precision EN threshold may be used to provide eventbased sequencing via feedback from other previously enabled regulators. All buck regulators have forward and reverse-current limiting, soft-start to limit inrush current during start-up, and short-circuit protection. 14 The buck switching regulators are phased in 90° steps to reduce noise and input ripple. The phase step determines the fixed edge of the switching sequence, which is when the PMOS turns on. The PMOS off (NMOS on) phase is subject to the duty cycle demanded by the regulator. Buck 1 is set to 0°, Buck 2 is set to 90°, Buck 3 is set to 270°, and Buck 4 is set to 180°. In shutdown all SW nodes are high impedance. The buck regulator enable pins may be tied to VOUT voltages through a resistor divider, to program power-up sequencing. The buck switching regulators feature a controlled shutdown scheme where the inductor current ramps down to zero through the NMOS switch. If any event causes the buck regulator to shut down (EN = LOW, OT, VINA-H or VCC UVLO) the NMOS switch turns on until the inductor current reaches 0mA (typical). Then, the switch pin becomes Hi-Z. Buck Regulators with Combined Power Stages Up to four adjacent buck regulators may be combined in a master-slave configuration by setting the configuration via the C1, C2, and C3 pins. These pins should either be tied to ground or pin strapped to VCC in accordance with the desired configuration code (Table 1). Any combined SW pins must be tied together, as must any of the combined VIN pins. EN1 and FB1 are utilized by Buck 1, EN2 and FB2 by Buck 2, EN3 and FB3 by Buck 3, and EN4 and FB4 by Buck 4. If any buck is not used or is not available in the desired configuration, then the associated FB and EN pins must be tied to ground. Any available combination of 2, 3, or 4 adjacent Buck regulators serve to provide up to either 2A, 3A, or 4A of average output load current. For example, code 110 (C3C2C1) configures Buck 1 to operate as a 4A regulator through VIN/SW pairs A, B, C, and D, while Buck 2 is disabled, Buck 3 operates as a 1A regulator through VIN/SW pair E, and Buck 4 operates as a 3A regulator through VIN/SW pairs F, G, and H. 3370fb For more information www.linear.com/LTC3370 LTC3370 Operation If none of the buck switching regulators are enabled, then the temperature monitor is also shut down to further reduce quiescent current. Table 1. Master Slave Program Combinations (Each Letter Corresponds to a VIN and SW Pair) PROGRAM CODE C3C2C1 BUCK 1 BUCK 2 BUCK 3 BUCK 4 000 AB CD EF GH 001 ABC D EF GH 010 ABC D E FGH 011 ABCH D E FG 100 ABC DE Not Used FGH 101 ABCD Not Used EF GH 110 ABCD Not Used E FGH 111 ABCD Not Used Not Used EFGH Selection of the operating frequency is a trade-off between efficiency and component size. High frequency operation allows the use of smaller inductor and capacitor values. Operation at lower frequencies improves efficiency by reducing internal gate charge losses but requires larger inductance values and/or capacitance to maintain low output voltage ripple. Power Failure Reporting Via PGOODALL Pin Power failure conditions are reported back by the PGOODALL pin. Each buck switching regulator has an internal power good (PGOOD) signal. When the regulated output voltage of an enabled switcher falls below 98% for Buck regulator 1 or 95% for Buck regulators 2-4 of its programmed value, the PGOOD signal is pulled low. If any PGOOD signal stays low for greater than 100µs, then the PGOODALL pin is pulled low, indicating to a microprocessor that a power failure fault has occurred. The 100µs filter time prevents the pin from being pulled low due to a transient. The PGOOD signal has a 0.3% hysteresis such that when the regulated output voltage of an enabled switcher rises above 98.3% or 95.3%, respectively, of its programmed value, the PGOOD signal transitions high. Temperature Monitoring and Overtemperature Protection To prevent thermal damage to the LTC3370 and its surrounding components, the LTC3370 incorporates an overtemperature (OT) function. When the LTC3370 die temperature reaches 170°C (typical) all enabled buck switching regulators are shut down and remain in shutdown until the die temperature falls to 160°C (typical). The temperature may be read back by the user by sampling the TEMP pin analog voltage. The temperature, T, indicated by the TEMP pin voltage is given by: T= VTEMP – 45mV •1°C 7mV Programming the Operating Frequency The operating frequency for all of the LTC3370 regulators is determined by an external resistor that is connected between the RT pin and ground. The operating frequency can be calculated using the following equation: 8 •1011 • ΩHz fOSC = RT (2) While the LTC3370 is designed to function with operating frequencies between 1MHz and 3MHz, it has safety clamps that will prevent the oscillator from running faster than 4MHz (typical) or slower than 250kHz (typical). Tying the RT pin to VCC sets the oscillator to the default internal operating frequency of 2MHz (typical). The LTC3370’s internal oscillator can be synchronized through an internal PLL circuit to an external frequency by applying a square wave clock signal to the PLL/MODE pin. During synchronization, the top MOSFET turn-on of Buck regulator 1 is phase locked to the rising edge of the external frequency source. All other buck switching regulators are locked to the appropriate phase of the external frequency source (see Buck Switching Regulators). The synchronization frequency range is 1MHz to 3MHz. A synchronization signal on the PLL/MODE pin will force all active buck switching regulators to operate in forced continuous mode PWM. (1) 3370fb For more information www.linear.com/LTC3370 15 Applications Information Buck Switching Regulator Output Voltage and Feedback Network The output voltage of the buck switching regulators is programmed by a resistor divider connected from the switching regulator’s output to its feedback pin and is given by VOUT = VFB(1 + R2/R1) as shown in Figure 1. Typical values for R1 range from 40kΩ to 1MΩ. The buck regulator transient response may improve with optional capacitor, CFF, that helps cancel the pole created by the feedback resistors and the input capacitance of the FB pin. Experimentation with capacitor values between 2pF and 22pF may improve transient response. VOUT BUCK SWITCHING REGULATOR CFF R2 FB R1 + COUT 3370 F01 OPTIONAL Figure 1. Feedback Components Buck Regulators All four buck regulators are designed to be used with inductors ranging from 1µH to 3.3µH depending on the lowest switching frequency at which the buck regulator must operate. When operating at 1MHz a 3.3µH inductor should be used, while at 3MHz a 1µH inductor may be used, or a higher value inductor may be used if reduced current ripple is desired. Table 2 shows some recommended inductors for the buck regulators. The bucks are compensated to operate across the range of possible VIN and VOUT voltages when the appropriate inductance is used for the desired switching frequency. The input supply should be decoupled with a 10µF capacitor while the output should be decoupled with a 22µF capacitor. Refer to the Capacitor Selection section for details on selecting a proper capacitor. Combined Buck Power Stages The LTC3370 has eight power stages that can handle average load currents of 1A each. These power stages may be combined in any one of eight possible combinations, via 16 the C1, C2, and C3 pins (see Table 1). Tables 3, 4, and 5 show recommended inductors for the combined power stage configurations. The input supply should be decoupled with a 22µF capacitor while the output should be decoupled with a 47µF capacitor for a 2A combined buck regulator. Likewise for 3A and 4A configurations the input and output capacitance must be scaled up to account for the increased load. Refer to the Capacitor Selection section for details on selecting a proper capacitor. In some cases it may be beneficial to use more power stages than needed to achieve increased efficiency of the active regulators. In general the efficiency will improve by adding stages for any regulator running close to what the rated load current would be without the additional stage. For example, if the application requires a 1A regulator that supplies close to 1A at a high duty cycle, a 3A regulator that only peaks at 3A but averages a lower current, and a 2A regulator that runs at 1.5A at a high duty cycle, better efficiency may be achieved by using the 3A, 3A, 2A configuration. Input and Output Decoupling Capacitor Selection The LTC3370 has individual input supply pins for each buck power stage and a separate VCC pin that supplies power to all top level control and logic. Each of these pins must be decoupled with low ESR capacitors to GND. These capacitors must be placed as close to the pins as possible. Ceramic dielectric capacitors are a good compromise between high dielectric constant and stability versus temperature and DC bias. Note that the capacitance of a capacitor deteriorates at higher DC bias. It is important to consult manufacturer data sheets and obtain the true capacitance of a capacitor at the DC bias voltage that it will be operated at. For this reason, avoid the use of Y5V dielectric capacitors. The X5R/X7R dielectric capacitors offer good overall performance. The input supply voltage Pins 1, 4, 5, 8, 17, 20, 21, 24 and 29 all need to be decoupled with at least 10µF capacitors. If power stages are combined the supplies should be shorted with as short of a trace as possible, and the decoupling capacitor should be scaled accordingly. 3370fb For more information www.linear.com/LTC3370 LTC3370 Applications Information Table 2. Recommended Inductors for 1A Buck Regulators PART NUMBER IHLP1212ABER1R0M-11 L (µH) MAX IDC (A) MAX DCR (mΩ) SIZE IN mm (L × W × H) 1.0 3 38 3 × 3.6 × 1.2 1239AS-H-1R0N 1 2.5 65 2.5 × 2.0 × 1.2 XFL4020-222ME 2.2 3.5 23.5 4 × 4 × 2.1 1277AS-H-2R2N 2.2 2.6 84 3.2 × 2.5 × 1.2 IHLP1212BZER2R2M-11 2.2 3 46 3 × 3.6 × 1.2 XFL4020-332ME 3.3 2.8 38.3 4 × 4 × 2.1 IHLP1212BZER3R3M-11 3.3 2.7 61 3 × 3.6 × 1.2 SIZE IN mm (L × W × H) MANUFACTURER Vishay Toko CoilCraft Toko Vishay CoilCraft Vishay Table 3. Recommended Inductors for 2A Buck Regulators PART NUMBER L (µH) MAX IDC (A) MAX DCR (mΩ) XFL4020-102ME 1.0 5.1 11.9 4 × 4 × 2.1 1 5 27 4.45 × 4.06 × 1.8 XAL4020-222ME 2.2 5.6 38.7 4 × 4 × 2.1 FDV0530-2R2M 2.2 5.3 15.5 6.2 × 5.8 × 3 IHLP2020BZER2R2M-11 2.2 5 37.7 5.49 × 5.18 × 2 XAL4030-332ME 3.3 5.5 28.6 4 × 4 × 3.1 FDV0530-3R3M 3.3 4.1 34.1 6.2 × 5.8 × 3 74437324010 MANUFACTURER CoilCraft Würth Elektronik CoilCraft Toko Vishay CoilCraft Toko Table 4. Recommended Inductors for 3A Buck Regulators PART NUMBER L (µH) MAX IDC (A) MAX DCR (mΩ) SIZE IN mm (L × W × H) 1.0 8.7 14.6 4 × 4 × 2.1 FDV0530-1R0M 1 8.4 11.2 6.2 × 5.8 × 3 XAL5030-222ME 2.2 9.2 14.5 5.28 × 5.48 × 3.1 IHLP2525CZER2R2M-01 2.2 8 20 6.86 × 6.47 × 3 Vishay 74437346022 2.2 6.5 20 7.3 × 6.6 × 2.8 Würth Elektronik XAL5030-332ME 3.3 8.7 23.3 5.28 × 5.48 × 3.1 SPM6530T-3R3M 3.3 7.3 27 7.1 × 6.5 × 3 XAL4020-102ME MANUFACTURER CoilCraft Toko CoilCraft CoilCraft TDK Table 5. Recommended Inductors for 4A Buck Regulators PART NUMBER XAL5030-122ME SPM6530T-1R0M120 L (µH) MAX IDC (A) MAX DCR (mΩ) SIZE IN mm (L × W × H) 1.2 12.5 9.4 5.28 × 5.48 × 3.1 1 14.1 7.81 7.1 × 6.5 × 3 XAL5030-222ME 2.2 9.2 14.5 5.28 × 5.48 × 3.1 SPM6530T-2R2M 2.2 8.4 19 7.1 × 6.5 × 3 IHLP2525EZER2R2M-01 2.2 13.6 20.9 6.86 × 6.47 × 5 XAL6030-332ME 3.3 8 20.81 6.36 × 6.56 × 3.1 FDVE1040-3R3M 3.3 9.8 10.1 11.2 × 10 × 4 MANUFACTURER CoilCraft TDK CoilCraft TDK Vishay CoilCraft Toko 3370fb For more information www.linear.com/LTC3370 17 LTC3370 Applications Information PCB Considerations When laying out the printed circuit board, the following list should be followed to ensure proper operation of the LTC3370: 1. The exposed pad of the package (Pin 33) should connect directly to a large ground plane to minimize thermal and electrical impedance. 2. Each of the input supply pins should have a decoupling capacitor. 3. The connections to the switching regulator input supply pins and their respective decoupling capacitors should be kept as short as possible. The GND side of these capacitors should connect directly to the ground plane of the part. These capacitors provide the AC current to the internal power MOSFETs and their drivers. It is important to minimize inductance from these capacitors to the VIN pins of the LTC3370. the switching nodes, high input impedance sensitive nodes, such as the feedback nodes, should be kept far away or shielded from the switching nodes or poor performance could result. 5. The GND side of the switching regulator output capacitors should connect directly to the thermal ground plane of the part. Minimize the trace length from the output capacitor to the inductor(s)/pin(s). 6. In a multiple power stage buck regulator application the trace length of switch nodes to the inductor must be kept equal to ensure proper operation. 7. Care should be taken to minimize capacitance on the TEMP pin. If the TEMP voltage must drive more than ~30pF, then the pin should be isolated with a resistor placed close to the pin of a value between 10k and 100k. Keep in mind that any load on the isolation resistor will create a proportional error. 4. The switching power traces connecting SWA, SWB, SWC, SWD, SWE, SWF, SWG, and SWH to the inductors should be minimized to reduce radiated EMI and parasitic coupling. Due to the large voltage swing of 18 3370fb For more information www.linear.com/LTC3370 LTC3370 Typical Applications 4 × 2A Quad Buck Application 2.25V TO 5.5V 22µF 1.2V 2A 2.2µH 47µF 232k VINA VINB VING VINH SWA SWB SWG SWH FB1 FB4 464k 2.5V 2A 2.2µH 47µF 2.2µH 806k 665k 47µF 1.8V 2A 649k LTC3370 2.5V TO 5.5V 22µF 2.25V TO 5.5V 22µF VINC VIND VINE VINF SWC SWD SWE SWF FB2 FB3 3.3V TO 5.5V 22µF 2.2µH 511k 309k 47µF 3.3V 2A 162k EN1 EN2 EN3 EN4 PLL/MODE C1 C2 C3 MICROPROCESSOR CONTROL RT 402k VCC 2.7V TO 5.5V 10µF PGOODALL TEMP EXPOSED PAD MICROPROCESSOR CONTROL 3370 TA02 3370fb For more information www.linear.com/LTC3370 19 LTC3370 Typical Applications Buck Regulators with Sequenced Start-Up Driven from a High Voltage Upstream Buck Converter VIN 5.5V TO 36V CIN 22µF VIN 100k INTVCC INTVCC 2.2µF PGOOD PLLIN/MODE 470pF SENSE+ 47µF 2.2µH 1.2V 4A COUT: SANYO 10TPE330M D1: DFLS1100 L1 COILCRAFT SER1360-802KL MTOP, MBOT: Si7850DP 100µF VINF VING SWH SWA SWB SWC FB1 232k 464k SWF SWG 22µF 22µF 2.2µH 806k 47µF 1.8V 2A 649k LTC3370 2.2µH 19.1k FB4 VIND 10µF 5V 6A 100k SGND VINH VINA VINB VINC COUT 330µF 1nF – TRACK/SS SENSE EXTVCC SGND VFB 1M RSENSE 7mΩ MBOT BG ITH 0.1µF L1 8µH SW FREQ 34.8k MTOP 0.1µF LTC3891 RUN BOOST TMR GND ON 2.5V 1A D1 TG ILIM LTC2955TS8-1 VIN EN KILL INT PB MICROPROCESSOR CONTROL PGND VINE SWD SWE FB2 FB3 10µF 2.2µH 665k 511k 309k 22µF 3.3V 1A 162k EN1 EN2 EN3 EN4 PLL/MODE C1 C2 C3 MICROPROCESSOR CONTROL VCC RT 402k VCC PGOODALL TEMP 10µF MICROPROCESSOR CONTROL EXPOSED PAD 3370 TA03 20 3370fb For more information www.linear.com/LTC3370 LTC3370 Typical Applications Combined Buck Regulators with Common Input Supply 2.7V TO 5.5V 10µF 1.2V 4A 2.2µH 100µF 324k VINA VINH SWA SWB SWC SWD FB1 SWH SWG SWF 2.2µH 511k 511k VINB VING 10µF LTC3370 10µF 10µF VINC VINF VIND VINE SWE 10µF 2.2µH 665k MICROPROCESSOR CONTROL 10µF FB4 649k 10µF 68µF 1.6V 3A FB2 EN2 C1 FB3 C2 C3 VCC 22µF 2.5V 1A 10µF 309k EN1 PGOODALL EN3 TEMP EN4 PLL/MODE RT EXPOSED PAD 10µF MICROPROCESSOR CONTROL 3370 TA04 3370fb For more information www.linear.com/LTC3370 21 LTC3370 Package Description Please refer to http://www.linear.com/product/LTC3370#packaging for the most recent package drawings. UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693 Rev D) 0.70 ±0.05 5.50 ±0.05 4.10 ±0.05 3.50 REF (4 SIDES) 3.45 ±0.05 3.45 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD LAYOUT APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 5.00 ±0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD 0.75 ±0.05 R = 0.05 TYP 0.00 – 0.05 R = 0.115 TYP PIN 1 NOTCH R = 0.30 TYP OR 0.35 × 45° CHAMFER 31 32 0.40 ±0.10 PIN 1 TOP MARK (NOTE 6) 1 2 3.50 REF (4-SIDES) 3.45 ±0.10 3.45 ±0.10 (UH32) QFN 0406 REV D 0.200 REF NOTE: 1. DRAWING PROPOSED TO BE A JEDEC PACKAGE OUTLINE M0-220 VARIATION WHHD-(X) (TO BE APPROVED) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 22 0.25 ±0.05 0.50 BSC 3370fb For more information www.linear.com/LTC3370 LTC3370 Revision History REV DATE DESCRIPTION A 03/16 Changed pin labeling on Typical Application circuit PAGE NUMBER 1 B 09/16 Changed Pin Configuration TJMAX to 150°C 3 3370fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. For more information www.linear.com/LTC3370 23 LTC3370 Typical Application Combined Bucks with 3MHz Switching Frequency and Sequenced Power Up 2.25V TO 5.5V 10µF 10µF 10µF 1.2V 3A 1µH 68µF 324k VINA VINH VINB VING 2.25V TO 5.5V 10µF 10µF 1µH VINC SWH SWG SWA SWB SWC FB4 FB1 VINF VIND LTC3370 3.3V 1A 22µF SWD 511k VINE FB2 SWE SWF 10µF 1µH MICROPROCESSOR CONTROL 2.5V 2A 47µF 665k FB3 309k 162k VCC 2.5V TO 5.5V 10µF 10µF 1µH 2V 2A 432k 649k 3.3V TO 5.5V 47µF 649k C1 C2 C3 2.7V TO 5.5V VCC PGOODALL TEMP PLL/MODE EN1 EN2 EN3 EN4 RT EXPOSED PAD 10µF MICROPROCESSOR CONTROL 267k 3370 TA05 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC3589 8-Output Regulator with Sequencing and I2C Triple I2C Adjustable High Efficiency Step-Down DC/DC Converters: 1.6A, 1A, 1A. High Efficiency 1.2A Buck-Boost DC/DC Converter, Triple 250mA LDO Regulators. Pushbutton On/Off Control with System Reset, Flexible Pin-Strap Sequencing Operation. I2C and Independent Enable Control Pins, Dynamic Voltage Scaling and Slew Rate Control. Selectable 2.25MHz or 1.12MHz Switching Frequency, 8µA Standby Current, 40-Lead (6mm × 6mm × 0.75mm) QFN. LTC3675 7-Channel Configurable High Power PMIC Quad Synchronous Buck Regulators (1A, 1A, 500mA, 500mA). Buck DC/DCs Can be Paralleled to Deliver Up to 2× Current with a Single Inductor. 1A Boost, 1A BuckBoost, 40V LED Driver. 44-Lead (4mm × 7mm × 0.75mm) QFN Package. LTC3676 8-Channel Power Management Solution for Application Processor Quad Synchronous Buck Regulators (2.5A, 2.5A, 1.5A, 1.5A). Quad LDO Regulators (300mA, 300mA, 300mA, 25mA). Pushbutton On/Off Control with System Reset. DDR Solution with VTT and VTTR Reference. 40-Lead (6mm × 6mm × 0.75mm) QFN Package. LTC3375 LTC3374 8-Channel Programmable Configurable 1A DC/DC 8 × 1A Synchronous Buck Regulators. Can Connect Up to Four Power Stages in Parallel to Make a Single Inductor, High Current Output (4A Maximum), 15 Output Configurations Possible, 48-Lead (7mm × 7mm × 0.75mm) QFN Package (LTC3375) 38-Lead (5mm × 7mm × 0.75mm) QFN and TSSOP Packages (LTC3374). LTC3371 4-Channel Configurable DC/DC with 8 × 1A Power Stages 4 Synchronous Buck Regulators with 8 × 1A Power Stages. Can Connect Up to Four Power Stages in Parallel to Make a Single Inductor, High Current Output (4A Maximum), 8 Output Configurations Possible, Precision RST Monitoring with Windowed Watchdog Timer (CT Programmable), 38-Lead (5mm × 7mm × 0.75mm) QFN and TSSOP Packages. 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC3370 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC3370 3370fb LT 0916 REV B • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2015
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