Datasheet LTC7899 (Analog Devices) - 2

link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 4 link to page 9 link to page 11 link to page 14 link to page 15 link to page 20 link to page 20 link to page 20 link to page 20 link to page 20 link to page 21 link to page 21 link to page 22 link to page 23 link to page 23 link to page 23 link to page 23 link to page 23 link to page 24 link to page 24 link to page 24 link to page 25 link to page 25 link to page 26 link to page 28 link to page 29 link to page 30 link to page 30 link to page 31
Data Sheet LTC7899 TABLE OF CONTENTS
Features .. 1 Applications ... 1 General Description ... 1 Typical Application .. 1 Revision History ... 3 Specifications ... 4 Absolute Maximum Ratings .. 9 Pin Configurations and Function Descriptions .. 11 Block Diagram .. 14 Typical Performance Characteristics ... 15 Theory of Operation .. 20 Main Control Loop ... 20 Power and Bias Supplies (VBIAS, EXTVCC, DRVCC, and INTVCC) .. 20 High-Side Bootstrap Capacitor .. 20 Dead Time Control (DTCA and DTCB Pins) .. 20 Start-Up and Shutdown (RUN and SS Pins) .. 21 Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) ... 21 Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins).. 22 PolyPhase Applications (CLKOUT and PHASMD Pins) .. 23 Output Overvoltage Protection .. 23 Operation at Low Input Voltage ... 23 BOOST Supply Refresh ... 23 Power Good ... 23 Applications Information .. 24 Inductor Value Calculation ... 24 Inductor Core Selection .. 24 Current Sense Selection ... 25 Low Value Resistor Current Sensing .. 25 Inductor DCR Current Sensing ... 26 Setting the Operating Frequency .. 28 Selecting the Light Load Operating Mode .. 29 Dead Time Control (DTCA and DTCB Pins) .. 30 DTCx Pins Tied to INTV - CC or VIN (Adaptive Dead Time Control) ... 30 DTCx pin connected with a resistor to V - IN : .. 31
analog.com
Rev. 0 2 of 50 Document Outline Features Applications General Description Typical Application TABLE OF CONTENTS Revision History Specifications Absolute Maximum Ratings Pin Configurations and Function Descriptions Block Diagram Typical Performance Characteristics Theory of Operation Main Control Loop Power and Bias Supplies (VBIAS, EXTVCC, DRVCC, and INTVCC) High-Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Start-Up and Shutdown (RUN and SS Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) PolyPhase Applications (CLKOUT and PHASMD Pins) Output Overvoltage Protection Operation at Low Input Voltage BOOST Supply Refresh Power Good Applications Information Inductor Value Calculation Inductor Core Selection Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Current Sensing Setting the Operating Frequency Selecting the Light Load Operating Mode Dead Time Control (DTCA and DTCB Pins) DTCx Pins Tied to INTVCC or VIN- (Adaptive Dead Time Control) DTCx pin connected with a resistor to VIN-: Power MOSFET Selection CIN and COUT Selection Setting the Output Voltage RUN Pin and Undervoltage Lockout Soft-Start (SS Pin) DRVCC and INTVCC Regulators (OPTI-DRIVE) Topside MOSFET Driver Supply (CB, DB) Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Application Related Parts Outline Dimensions Ordering Guide