LTC7103 (Rev. B) - Analog Devices

1 LTC71031 Rev. BFor more information FeedbackTYPICAL APPLICATION FEATURESDESCRIPTION105V, Low EMI Synchronous Step-Down RegulatorThe LT C 7103 is a high efficiency, monolithic synchro-nous step-down DC/DC converter utilizing a constant frequency, average current mode control architecture. It operates from an input voltage range of to 105V and provides an adjustable regulated output voltage from 1V to VIN while delivering up to of output current. The LTC7103 features high frequency operation and a low minimum on-time that reduce inductor size and enable constant-frequency operation even at very high step-down ratios. In addition, the LTC7103 achieves the low-est possible dropout voltage with 100% maximum duty cycle operation. During light load operation, converter efficiency and output ripple can be optimized by selecting Burst Mode or pulse-skipping LTC7103 includes accurate, high speed average cur-rent programming and monitoring without the need for an external sense resistor.

2 Additional features include a bypass LDO to maximize efficiency, fixed or adjustable output voltage and loop compensation, and a wide array of protection features to enhance reliability. 5V to 105V Input to 5 Output Step-Down RegulatorEfficiency vs Load CurrentAPPLICATIONS nWide VIN Range: to 105V (110V Abs Max) nUltralow EMI/EMC Emissions: CISPR25 Compliant n2 A IQ When Regulating 48 VIN to nFast and Accurate Output Current Programming and Monitoring with No External RSENSE nBrick Wall Current Limit nLow Minimum On-Time: 40ns nWide VOUT Range: 1V to VIN n100% Maximum Duty Cycle Operation nProgrammable Fixed Frequency: 200kHz to 2 MHz nEight, Pin-Selectable Fixed ( to 15V) or Adjustable Output Voltages nSelectable Pulse-Skipping or Low Ripple Burst Mode Operation at Light Loads nPLL Synchronization to External Clock nEXTVCC LDO Powers Chip from VOUT = to 40V nOPTI-LOOP or Fixed Internal Compensation nInput and Output Overvoltage Protection nThermally Enhanced (5mm 6mm) QFN Package nBattery Chargers and CC/CV Supplies nAutomotive and Military Systems nIndustrial, Avionics and Heavy Equipment nMedical Instruments and Telecommunication Systems7103 F1 TO 105 VOVLOPLLIN/MODELTC7103 INTVCCITHPGNDSGND100 F18 HVOUT = 5 VVIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VLOAD CURRENT (mA) (%)7103 TA01bfSW = 300kHzFIGURE 14 CIRCUITAll registered trademarks and trademarks are the property of their respective owners.

3 LTC71032 Rev. BFor more information CONFIGURATIONABSOLUTE MAXIMUM RATINGSVIN Supply Voltage .. to 110 VINTVCC, (BOOST-SW) Voltages .. to 6 VBOOST Voltage .. to 110 VRUN to 110 VVFB, PGOOD Voltages .. to 16 VEXTVCC Voltage .. to 41 VRIND, VPRG1, VPRG2 Voltages .. to INTVCCICTRL, SS Voltages .. to INTVCCFREQ, ITH, PLLIN/MODE, OVLO to 6V Operating Junction Temperature Range (Notes 2, 3, 4) LTC7103E, LTC7103I .. 40 C to 125 C LTC7103H .. 40 C to 150 C LTC7103MP .. 55 C to 150 CStorage Temperature Range .. 65 C to 150 C(Note 1)11121314 TOP VIEWPGND37 UHE36(26) PACKAGE36-LEAD (5mm 6mm) PLASTIC QFNTJMAX = 150 C, JA = 38 C/WEXPOSED PAD (PIN 37) IS PGND, MUST BE SOLDERED TO PCB15161718363532313021242526278763 RUNSGNDOVLORINDITHVFBBOOSTSWSWSWINTVCCEX TVCCVPRG2 PGNDPGNDVINVINVINFREQPLLIN/MODECLKOUTPGO ODSSICTRLIMONVPRG12019910 LEAD FREE FINISHTAPE AND REELPART MARKING*PACKAGE DESCRIPTIONTEMPERATURE RANGELTC7103 EUHE#PBFLTC7103 EUHE#TRPBF710336-Lead (5mm 6mm) Plastic QFN 40 C to 125 CLTC7103 IUHE#PBFLTC7103 IUHE#TRPBF710336-Lead (5mm 6mm) Plastic QFN 40 C to 125 CLTC7103 HUHE#PBFLTC7103 HUHE#TRPBF710336-Lead (5mm 6mm) Plastic QFN 40 C to 150 CLTC7103 MPUHE#PBFLTC7103 MPUHE#TRPBF710336-Lead (5mm 6mm) Plastic QFN 55 C to 150 CContact the factory for parts specified with wider operating temperature ranges.

4 *The temperature grade is identified by a label on the shipping and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF INFORMATIONLTC71033 Rev. BFor more information CHARACTERISTICSSYMBOLPARAMETERCONDITIONS MINTYPMAXUNITSMain Regulator and Voltage LoopVINO perating Input Voltage (UVLO)VIN Undervoltage LockoutVIN Rising VIN Fallingl VVOUTO perating Output Voltage Range(Note 9) Input DC Supply Current(Note 8)Pulse-Skipping ModeVFB = , EXTVCC = VFB = , EXTVCC = 0V200 A mASleep ModeVFB = , EXTVCC = 5V VFB = , EXTVCC = A AShutdownRUN = AVIN Input Current In RegulationFigure 14 Circuit, VIN = 48V, IOUT = 500 A Figure 16 Circuit, VIN = 48V, IOUT = 0 A64 275 A AVFBR egulated Feedback Voltage(Note 5) ITH Voltage = to , VIN = to 105V VPRG1 = VPRG2 = FLOAT VPRG1 = VPRG2 = INTVCC VPRG1 = FLOAT, VPRG2 = INTVCC VPRG1 = VPRG2 = SGND VPRG1 = SGND, VPRG2 = FLOAT VPRG1 = SGND, VPRG2 = INTVCC VPRG1 = FLOAT, VPRG2 = SGND VPRG1 = INTVCC, VPRG2 = FLOAT VPRG1 = INTVCC, VPRG2 = SGND l l l l l l l l l V V V V V V V V VFeedback Input Bias CurrentVPRG1 = VPRG2 = FLOAT VPRG1 or VPRG2 Tied to SGND or INTVCC 2 10 AgmError Amplifier gmITH = 1V, Sink/Source = 5 A (Note 5) ,MINM inimum Controllable ON-Time(Note 7)l4060nsRDS(ON)TOPTop Switch On-Resistance265m RDS(ON)BOTB ottom Switch On-Resistance142m Current Control and MonitoringILIM(AVG)Average Output Current Limit(Note 6) ICTRL = FLOAT ICTRL = A AIPKTop Switch Peak Current LimitICTRL = FLOAT ICTRL = AVIMONC urrent Monitor Output Voltage(Note 6)

5 ISW = 2A ISW = V VICTRL Pin Pull-Up CurrentVICTRL = 1Vl182022 AStart-Up and ShutdownISSSoft-Start Charge CurrentSS = 0Vl81114 AtSS(INT)Internal Soft-Start Ramp TimeSS = (OV)Feedback Overvoltage ProtectionRelative to Regulated VFB71013%VRUN(ON)RUN Pin ON ThresholdVRUN Rising VRUN Fallingl VRUN Pin Hysteresis100mVRUN Pin Leakage CurrentRUN = 10010nAVOV(R)OVLO Pin Rising ThresholdVOVLO The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25 C. (Note 2) VIN = 12V unless otherwise BFor more information Pin Hysteresis65mVOVLO Pin Leakage CurrentOVLO = 10010nABias Regulators and HousekeepingINTVCC Undervoltage LockoutINTVCC Rising INTVCC Falling V VVEXTVCCEXTVCC Switchover VoltageEXTVCC Rising EXTVCC Fallingl VRegulated INTVCC Voltage from INTVCC Voltage from and Phase-Locked LoopProgrammable Frequency AccuracyRFREQ = (200kHz) to (2 MHz) PLLIN/MODE = 0Vl 1515%fLOWLow Preset FrequencyVFREQ = 0V; PLLIN/MODE = 0Vl270300330kHzfHIGHHigh Preset FrequencyVFREQ = INTVCC.

6 PLLIN/MODE = FrequencyPLLIN/MODE = External Clockl2002000kHzPLLIN/MODE Input High Level for ClockingPLLIN/MODE = External Input Low Level for ClockingPLLIN/MODE = External OutputPGOOD Voltage LowIPGOOD = Leakage CurrentVPGOOD = 12V 11 APGOOD Trip LevelVFB with Respect to Set Regulated VoltageVFB Ramping Positive71013% Ramping Negative 13 10 7% for Reporting a Fault24 sELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25 C. (Note 2) VIN = 12V unless otherwise 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 2: The LTC7103E is guaranteed to meet specifications from 0 C to 85 C with specifications over the 40 C to 125 C operating junction temperature range assured by design, characterization and correlation with statistical process controls.

7 The LTC7103I is guaranteed over the 40 C to 125 C operating junction temperature range, the LTC7103H is guaranteed over the 40 C to 150 C operating junction temperature range, and the LTC7103MP is tested and guaranteed over the 55 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 3: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD qJA C/W)Note 4: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. The maximum rated junction temperature will be exceeded when this protection is active.

8 Continuous operation above the specified absolute maximum operating junction temperature may impair device reliability or permanently damage the device. The overtemperature protection level is not production 5: The LTC7103 is tested in a feedback loop that servos VFB to a voltage near the internal reference voltage to obtain the specified ITH 6: The Average Output Current Limit, the Top Switch Peak Current Limit and the Current Monitor Output Voltage are measured in a test circuit that simulates operation in a typical application. Note 7: The minimum controllable on-time is measured in a test mode. (See Minimum ON-Time Considerations in the Applications Information section.) Note 8: Dynamic supply current is higher due to the internal gate charge being delivered at the switching frequency. Note 9: See Operating at VOUT > 6V in the Applications Information section for details about additional design constraints that may BFor more information PERFORMANCE CHARACTERISTICSP ulse-Skipping Mode Efficiency at 5 VOUTP ulse-Skipping Mode Efficiency at 12 VOUTP ulse-Skipping Mode Efficiency at Mode Efficiency at 5 VOUTTA = 25 C, unless otherwise Mode Efficiency at 12 VOUTB urst Mode Efficiency at vs Input VoltageVOUT = 5V, Burst Mode OperationEfficiency vs Frequency at 1 AVIN Input Current in Regulation vs Input VoltageVIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VLOAD CURRENT (mA) 50556065707580859095100 EFFICIENCY (%)7103 G01 FIGURE 14 CIRCUITfSW = 300kHzVIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VLOAD CURRENT (mA) 50556065707580859095100 EFFICIENCY (%)7103 G03 FIGURE 16 CIRCUITfSW = 300kHzVIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VLOAD CURRENT (mA)10100100030405060708090100 EFFICIENCY (%)

9 7103 G04 FIGURE 14 CIRCUITfSW = 300kHzVIN = 24 VVIN = 48 VVIN = 72 VVIN = 100 VLOAD CURRENT (mA)10100100030405060708090100 EFFICIENCY (%)7103 G05fSW = 300kHzFIGURE 15 CIRCUITfSW = 300kHzFIGURE 14 CIRCUITILOAD = 2 AILOAD = 1 AILOAD = 100mAILOAD = 10mAINPUT VOLTAGE (V)02040608010050556065707580859095100 EFFICIENCY (%)7103 G07 VOUT = = 0 FIGURE 16 CIRCUITVIN VOLTAGE (V)01020304050607080901000246810 VIN SUPPLY CURRENT ( A)7103 G09 VIN = 24 VVIN = 48 VVIN = 72 VVIN = 100 VLOAD CURRENT (mA) 50556065707580859095100 EFFICIENCY (%)7103 G02 FIGURE 15 CIRCUITfSW = 300kHzLOAD CURRENT (mA)10100100030405060708090100 EFFICIENCY (%)7103 G06 VIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VFIGURE 16 CIRCUITfSW = 300kHzVIN = 12 VVIN = 24 VVIN = 48 VVIN = 72 VFREQUENCY (MHz) (%)7103 G08 ILOAD = 1 AFIGURE 14 CIRCUITLTC71036 Rev. BFor more information Feedback Voltage vs TemperatureAverage Output Current vs VIN, ICTRLA verage Output Current vs TemperaturePeak Current Limit vs TemperatureOutput Current Monitor vs Average Output CurrentOutput Current Monitor Error vs Average Output CurrentTop and Bottom Switch Resistance vs TemperatureMinimum On-Time vs TemperatureOscillator Frequency vs TemperatureTYPICAL PERFORMANCE CHARACTERISTICSTA = 25 C, unless otherwise = FLOATVPRG2 = FLOATTEMPERATURE ( C) 55 FEEDBACK VOLTAGE (V)7103 G10 ICTRL = = = 14 CIRCUITVIN VOLTAGE (V) OUTPUT CURRENT (A)7103 G11 TEMPERATURE ( C) 55 CURRENT LIMIT (A)7103 G13 FIGURE 14 CIRCUITVIN = 24 VVIN = 48 VVIN = 72 VAVERAGE OUTPUT CURRENT (A) VOLTAGE (V)7103 G14 TOP SWITCHBOTTOM SWITCHTEMPERATURE ( C) 55 2553565951251555010015020025030035040045 0500550 RESISTANCE (m )7103 G16 TEMPERATURE ( C) 55 255356595125155303540455055 MINIMUM ON-TIME (ns)7103 G17 FREQ = GND (300kHz)FREQ = (200kHz)FREQ = (2 MHz)

10 FREQ = INTVCC (1 MHz)TEMPERATURE ( C) 55 255356595125155 3 2 10123 CHANGE IN FREQUENCY (%)7103 G18 VICTRL = = 14 CIRCUITTEMPERATURE ( C) 55 OUTPUT CURRENT (A)7103 G12 FIGURE 14 CIRCUITVIN = 72 VVIN = 48 VVIN = 24 VAVERAGE OUTPUT CURRENT (A) VOLTAGE ERROR (%)7103 G15 LTC71037 Rev. BFor more information Input Current vs Input VoltageVIN Quiescent Current vs TemperatureInductor Current at Light LoadLoad Step Burst Mode OperationLoad Step Pulse-Skipping ModeSW Node Waveform at Full LoadTYPICAL PERFORMANCE CHARACTERISTICSTA = 25 C, unless otherwise to External ClockStart-Up from ShutdownShort-Circuit and RecoverySLEEP, EXTVCC = GNDSHUTDOWNVIN VOLTAGE (V)01530456075901050246810 VIN SUPPLY CURRENT ( A)7103 G19 SLEEPSHUTDOWNEXTVCC = GNDVIN = 100 VTEMPERATURE ( C) 55 25535659512515505101520253035 VIN SUPPLY CURRENT ( A)7103 G20 VIN = 48 VILOAD = 200 AFIGURE 14 CIRCUIT10 s/DIVPULSE SKIPPINGMODE200mA/DIVB urst ModeOPERATION500mA/DIV7103 G21 LOAD STEP = 50mA TO 1 AVIN = 48 VFIGURE 14 CIRCUIT40 s/DIVVOUT100mV/DIVIL1A/DIV7103 G22 LOAD STEP = 50mA TO 1 AVIN = 48 VFIGURE 14 CIRCUIT40 s/DIVVOUT100mV/DIVIL1A/DIV7103 G23 VIN = 48 VILOAD = 14 CIRCUIT50ns/DIVVSW10V/DIV7103 G24 VIN = 48 VBurst Mode OPERATIONFIGURE 14 CIRCUIT200 s/DIVVOUT2V/DIVIL500mA/DIVVRUN5V/DIV7103 G26 VIN = 48 VPULSE SKIPPING MODEFIGURE 14 CIRCUIT100 s/DIVVOUT2V/DIVIL1A/DIV7103 G27 VIN = 48 VILOAD = 1 AFIGURE 14 CIRCUIT10 s/DIVVSW20V/DIVEXTERNALCLOCK ONPLLIN/MODE2V/DIV7103 G25 LTC71038 Rev.