POWER LOSS (W) LTC7810 150V Low I , Dual, 2-Phase Q Synchronous Step-Down DC/DC Controller FEATURES DESCRIPTION n Wide V Range: 4.5V to 140V (150V Abs Max) The LTC 7810 is a high performance dual step-down DC/ IN n Wide Output Voltage Range: 1V V 60V DC switching regulator controller that drives all N-channel OUT n Low Operating I : 16A (48V to 12V and 3.3V ) synchronous power MOSFET stages that can operate Q IN OUT OUT n Adjustable Gate Drive Level Up to 10V from voltages up to 140V. A constant frequency current n Optional Spread Spectrum Operation mode architecture allows a phase-lockable frequency of n Very Low Dropout: 100% Duty Cycle Operation up to 720kHz. n Low I in Dropout: 78A (One Channel On) Q The low no-load quiescent current extends operating run n R or Inductor DCR Current Sensing SENSE time in battery-powered systems. The LTC7810 features n Out-of-Phase Controllers Reduce Required Input a precision 1V reference, enabling the output voltage to Capacitance and Power Supply Induced Noise be programmed from 1V to 60V. The gate drive voltage n Phase-Lockable Frequency (75kHz to 720kHz) for the LTC7810 can be programmed to 6V, 8V, or 10V n Programmable Fixed Frequency (50kHz to 750kHz) to allow the use of logic-level or standard-threshold FETs n Selectable Continuous, Pulse-Skipping, or Low Ripple and to maximize efficiency. Burst Mode Operation at Light Loads n The LTC7810 additionally features spread spectrum oper- Onboard LDO or External NMOS LDO for DRV CC ation which significantly reduces the peak radiated and n EXTV LDO Powers Drivers from V CC OUT n conducted noise on both the input and output supplies, Programmable Input Overvoltage Lockout making it easier to comply with electromagnetic interfer- n 48-Lead (7mm 7mm) eLQFP Package ence (EMI) standards. All registered trademarks and trademarks are the property of their respective owners. APPLICATIONS n Automotive and Transportation n Industrial and Telecommunications n Military/Avionics TYPICAL APPLICATION High Efficiency Dual 12V/5V Output Step-Down Regulator with Spread Spectrum Efficiency and Power Loss DRV CC V IN vs Load Current 12.5V to 140V 2.2F RUN1 V RUN2 DRV IN CC 100 100 V = 12V BOOST1 BOOST2 OUT TG1 TG2 10H 0.1F 0.1F 33H 90 10 SW1 SW2 EFFICIENCY LTC7810 BG1 BG2 80 1 POWER LOSS + + SENSE1 SENSE2 10m 8m 70 0.1 SENSE1 SENSE2 V V OUT2 OUT1 EXTV CC 12V/5A 5V/6A 220k 22pF 220k 60 0.01 470F 150F V V V = 24V FB1 FB2 IN ITH1 ITH2 V = 72V IN TRACK/SS1 TRACK/SS2 55k 20k V = 140V IN DRVSET NDRV DRV CC 50 0.001 17.4k INTV 0.1F CC MODE 0.001 0.01 0.1 1 10 12.1k PLLIN/SPREAD REGSD 0.1F LOAD CURRENT (A) OVLO GND FREQ 1.5nF 7810 TA01b 1.5nF 0.1F 7810 TA01a Rev. A 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC7810 TABLE OF CONTENTS Features ..................................................... 1 Inductor Core Selection ..........................................21 Applications ................................................ 1 Power MOSFET Selection .......................................21 Typical Application ........................................ 1 C and C Selection ...........................................22 IN OUT Description.................................................. 1 Setting the Output Voltage ......................................22 Absolute Maximum Ratings .............................. 3 RUN Pins and Overvoltage/Undervoltage Order Information .......................................... 3 Lockout ...................................................................23 Pin Configuration .......................................... 3 Tracking and Soft-Start (TRACK/SS1, Electrical Characteristics ................................. 4 TRACK/SS2 Pins) ................................................... 24 Typical Performance Characteristics ................... 7 Single Output Two-Phase Operation .......................25 Pin Functions .............................................. 10 DRV Regulators ...................................................25 CC Functional Diagram ...................................... 12 Topside MOSFET Driver Supply (C , D ) ................27 B B Operation................................................... 13 Burst Clamp Programming .....................................28 Main Control Loop .................................................. 13 Fault Conditions: Current Limit and Power and Bias Supplies (V , NDRV, EXTV , Current Foldback .....................................................29 IN CC DRV , REGSD) ...................................................... 13 Fault Conditions: Overvoltage CC Boost Supply and Dropout (BOOST and Protection (Crowbar) ..............................................29 SW pins) ................................................................. 14 Fault Conditions: Overtemperature Protection ........29 Start-Up and Shutdown (RUN, TRACK/SS, Phase-Locked Loop and Frequency OVLO Pins) ............................................................. 14 Synchronization ......................................................29 Light Load Operation: Burst Mode Operation, Minimum On-Time Considerations..........................30 Pulse Skipping or Forced Continuous Efficiency Considerations .......................................30 Mode (MODE Pin) ................................................... 14 Checking Transient Response .................................31 Frequency Selection, Spread Spectrum, Design Example ......................................................32 and Phase-Locked Loop (FREQ and PC Board Layout Checklist .....................................33 PLLIN/SPREAD Pins) .............................................. 16 PC Board Layout Debugging ...................................35 Applications Information ................................ 17 Typical Applications ...................................... 36 Current Sense Selection ......................................... 17 Package Description ..................................... 40 Low Value Resistor Current Sensing ....................... 17 Revision History .......................................... 41 Inductor DCR Sensing ............................................ 17 Typical Application ....................................... 42 Setting the Operating Frequency............................. 19 Related Parts .............................................. 42 Selecting the Light-Load Operating Mode ............... 19 Inductor Value Calculation ......................................20 Rev. A 2 For more information www.analog.com