Virtual Remote Sense Controller Features: Tight Load Regulation with Highly Resistive Cables without Requiring Remote Sense Wiring Compatible with Isolated and Nonisolated Power Supplies ±1% Internal Voltage Reference 5mA Sink Current Capability Soft-Correct Reduces Turn-On Transients Undervoltage and Overvoltage Protection Pin-Programmable Dither Frequency Optional Spread Spectrum Dither Wide VIN Range: 3.1V to 50V 24-Pin SSOP Package

Virtual Remote Sense Controller Features: Tight Load Regulation with Highly Resistive Cables without Requiring Remote Sense Wiring Compatible with Isolated and Nonisolated Power Supplies ±1% Internal Voltage Reference 5mA Sink Current Capability Soft-Correct Reduces Turn-On Transients Undervoltage and Overvoltage Protection Pin-Programmable Dither Frequency Optional Spread Spectrum Dither Wide VIN Range: 3.1V to 50V 24-Pin SSOP Package

Negative 48V Hot Swap Controller Features: Allows Safe Board Insertion and Removal from a Live –48V Backplane Circuit Breaker Immunity to Voltage Steps and Current Spikes Programmable Inrush and Short-Circuit Current Limits Pin Compatible with LT1640L/LT1640H Operates from –18V to –80V Programmable Overvoltage Protection Programmable Undervoltage Lockout Power Good Control Output Bell-Core Compatible ON/OFF Threshold

Negative 48V Hot Swap Controller Features: Allows Safe Board Insertion and Removal from a Live –48V Backplane Circuit Breaker Immunity to Voltage Steps and Current Spikes Programmable Inrush and Short-Circuit Current Limits Pin Compatible with LT1640L/LT1640H Operates from –18V to –80V Programmable Overvoltage Protection Programmable Undervoltage Lockout Power Good Control Output Bell-Core Compatible ON/OFF Threshold

Positive High Voltage Hot Swap Controller with Open-Circuit Detect Features: Allows Safe Board Insertion and Removal from a Live Backplane Controls Supply Voltage from 10.8V to 80V Foldback Current Limiting Open Circuit and Overcurrent Fault Detect Drives an External N-Channel MOSFET Automatic Retry or Latched Off Operation After Overcurrent Fault Programmable Supply Voltage Power-Up Rate Open MOSFET Detection 1% Over and Undervoltage Detection Accuracy Available in a 16-Lead SSOP Package

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/PoE+/PoE PD Controller Features: IEEE 802.3af/at and LTPoE++™ Powered Device (PD) Controller LTPoE++ Supports Power Levels Up to 90W LT4275A Supports All of the Following Standards: LTPoE++ 38.7W, 52.7W, 70W and 90W IEEE 802.3at 25.5W Compliant IEEE 802.3af Up to 13W Compliant LT4275B is IEEE 802.3at/af Compliant LT4275C is IEEE 802.3af Compliant 100V Absolute Maximum Input Voltage Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap™ N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Programmable Aux Power Support as Low as 9V Optional Support of Non-Standard Low Voltage PoE Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

LTPoE++/IEEE 802.3bt PD Interface Controller Features: LTPoE++®/IEEE 802.3bt Powered Device (PD) Controller Supports Up to 90W PDs Distinguishes Between LTPoE++ and IEEE 802.3bt PSEs 5-Event Classification Sensing Superior Surge Protection (100V Absolute Maximum) Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Configurable Aux Power Support as Low as 9V Pin Compatible with LT4275A/B/C and LT4294 Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

IEEE 802.3bt PD Interface Controller Features: IEEE 802.3af/at/bt Powered Device (PD) Controller Supports Up to 71.3W PDs 5-Event Classification Sensing Superior Surge Protection (100V Absolute Maximum) Wide Junction Temperature Range (–40°C to 125°C) Overtemperature Protection Integrated Signature Resistor External Hot Swap N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency Configurable Aux Power Support as Low as 9V Easy Migration Between LTPoE++® PDs and IEEE 802.3bt PDs Pin Compatible with LT4275A/B/C Available in 10-Lead MSOP and 3mm × 3mm DFN Packages

IEEE 802.3bt PD Interface with Forward/Flyback Controller Features: IEEE 802.3af/at/bt Powered Device (PD) with Forward/Flyback Controller Supports Up to 71.3W PDs 5-Event Classification Sensing Superior Surge Protection (100V Absolute Maximum) Wide Junction Temperature Range (–40°C to 125°C) >94% End-to-End Efficiency with LT4321 Ideal Bridge External Hot Swap N-Channel MOSFET for Lowest Power Dissipation and Highest System Efficiency No-Opto Flyback Operation Auxiliary Power Support as Low as 9V Easy Migration of LTPoE++® PDs to IEEE 802.3bt PDs Pin Compatible with LT4276A/B/C 28-Lead 4mm × 5mm QFN Package

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages

High Voltage Surge Stopper with Current Limit Features: Withstands Surges Over 80V with VCC Clamp Wide Operating Voltage Range: 4V to 80V Adjustable Output Clamp Voltage Fast Overcurrent Limit: Less Than 5μs Reverse Input Protection to –60V Adjustable UV/OV Comparator Thresholds Low 7μA Shutdown Current Shutdown Pin Withstands –60V to 100V Adjustable Fault Timer Controls N-Channel MOSFET Less Than 1% Retry Duty Cycle During Faults, LT4363-2 Available in 12-Pin (4mm × 3mm) DFN, 12-Pin MSOP or 16-Pin SO Packages