LT8228 Bidirectional Synchronous 100V Buck/Boost Controller with Reverse Supply, Reverse Current and Fault Protection FEATURES DESCRIPTION n Bidirectional Voltage or Current Regulation The LT 8228 is a 100V bidirectional constant-current or n Bidirectional Reverse Current Protection constant-voltage synchronous buck or boost controller n Input and Output Negative Voltage Protection to 60V with independent compensation network. The direction of n Bidirectional Inrush Current Limit and Boost Output the power flow is automatically determined by the LT8228 Short Protection or externally controlled. The input and output protec- n Switching MOSFET Short Detection and Protection tion MOSFETs protect against negative voltages, control n 10V Gate Drive inrush currents and provide isolation between terminals n Wide Input and Output Voltage Range Up to 100V under fault conditions such as switching MOSFET shorts. n Feedback Voltage Tolerance: 1.0% Over Temperature In buck mode, the protection MOSFETs at the V termi- 1 n Bidirectional Programmable Current Regulation and nal prevents reverse current. In boost mode, the same Monitoring MOSFETs regulate the output inrush current and protects n Extensive Self-Test, Diagnostics and Fault Reporting itself with an adjustable timer circuit breaker. n Programmable Fixed or Synchronizable Switching The LT8228 offers bidirectional input and output cur- Frequency: 80kHz to 600kHz rent limit as well as independent current monitoring. n Programmable Soft-Start and Dynamic Current Limit Masterless, fault tolerant current sharing allows any n Masterless, Fault Tolerant Current Sharing LT8228 in parallel to be added or subtracted while main- taining current sharing accuracy. Internal and external APPLICATIONS fault diagnostics and reporting are available via the FAULT n and REPORT pins. The LT8228 is available in a 38-lead Dual Battery Automotive and Industrial Systems n TSSOP package. High Power System Backup and Supply Stabilization n N+1 Redundant, High Reliability Power Supplies All registered trademarks and trademarks are the property of their respective owners. n Power Interrupt Protection System TYPICAL APPLICATION Simplified Bidirectional Battery Backup System Buck and Boost Mode Transitions BOOST (48V AT 10A) 2m V 1 I L SUPPLY 20A/DIV 24V TO BUCK (14V AT 40A) 54V 10H 2m DRV CC V 2 BATTERY 14V DRXN 2V/DIV 8228 TA01b SNS1P SNS1N TG BST SW BG SNS2P SNS2N 50s/DIV V1D DS2 DS1 DG2 C V DD DG1 LT8228 V BIAS 1 I L FAULT 20A/DIV V 2 REPORT DRV CC C I/O DRXN DRXN GND 2V/DIV 8228 TA01a 8228 TA1c 100s/DIV Rev. 0 1 Document Feedback For more information www.analog.comLT8228 TABLE OF CONTENTS Features ..................................................... 1 R Selection for V Output Current SET2P 2 Applications ................................................ 1 Limit (Buck Mode) .................................................36 Typical Application ........................................ 1 R Selection for V Input Current SET2N 2 Description.................................................. 1 Limit (Boost Mode) ................................................37 Absolute Maximum Ratings .............................. 3 R Selection for V Current Monitoring ............38 MON2 2 Order Information .......................................... 3 R and R Selection ........................................38 SNS1 IN1 Pin Configuration .......................................... 3 R Selection for V Input Current SET1P 1 Electrical Characteristics ................................. 4 Limit (Buck Mode) .................................................39 Typical Performance Characteristics ................... 9 R Selection for V Output Current SET1N 1 Buck Efficiency and Operation ..................................9 Limit (Boost Mode) ................................................40 Typical Performance Characteristics .................. 11 R Selection for V Current Monitoring ............ 41 MON1 1 Boost Efficiency and Operation ............................... 11 Output Voltage, Input Undervoltage and Output ENABLE, Supply Current and V Overvoltage Programming ...................................... 41 CC ................................... 13 SS Current, Frequency, Thresholds and Driver ...... 15 Power MOSFET Selection and Efficiency Protection MOSFET Controller ................................ 15 Considerations ........................................................42 Pin Functions .............................................. 16 Optional Schottky Diode (D2 and D3) Selection .....45 Block Diagram ............................................. 23 Top MOSFET Driver Supply (C , D ) ................46 BST BST Operation................................................... 24 Power Path Capacitor Selection ..............................46 Overview ................................................................. 24 Loop Compensation ................................................48 Buck Mode Operation ............................................. 24 Inrush Current Control ............................................49 Boost Mode Operation ............................................25 Boost Output Short Protection and Timer...............50 V Protection MOSFET Controller Operation ..........26 FAULT Conditions ....................................................52 1 V Protection MOSFET Controller Operation ..........28 Soft-Start ................................................................53 2 Mode of Operation (DRXN) .....................................28 REPORT Feature ......................................................53 Enable and Soft-Start (Enable and SS) ...................29 Paralleling Multiple LT8228s ...................................56 Paralleling Multiple Controllers (ISHARE BIAS, DRV , INTV and Power Dissipation .........57 CC CC and IGND) ...............................................................30 Thermal Shutdown .................................................58 BIAS Supply and V Regulators ............................31 Pin Clearance/Creepage Consideration ...................59 CC Strong Gate Drivers ................................................32 Efficiency Considerations .......................................59 Frequency Selection, Spread Spectrum and Phase- PC Board Layout Checklist .....................................59 Locked Loop (RT and SYNC) ..................................32 Design Example ......................................................60 FAULT Monitoring and REPORT Feature ..................32 Package Description ..................................... 67 Applications Information ................................ 33 Typical Application ....................................... 68 Introduction ............................................................33 Related Parts .............................................. 68 Programming the Switching Frequency ..................33 Inductor Selection...................................................34 R and R Selection for Peak Inductor SNS2 IN2 Current ....................................................................35 Rev. 0 2 For more information www.analog.com