Analog Devices Inc./Maxim Integrated

The LT4256-3 is a high voltage Hot Swap™controller that allows a board to be safely inserted and removed from a live backplane. An internal driver controls the high side N-channel MOSFET gate for supply voltages ranging from 10.8V to 80V. The part features an open-circuit detect (OPEN) output that indicates abnormally low load current conditions.The LT4256-3 also features an adjustable analog foldback current limit. If the supply remains in current limit for more than a programmable time, the N-channel MOSFET shuts off, the PWRGD output asserts low and the LT4256-3 either automatically restarts after a time-out delay or latches off until the UV pin is cycled low (depending on the status of the RETRY pin).The PWRGD output indicates when the output voltage rises above a programmed level. An external resistor string from VCCprovides programmable undervoltage and overvoltage protection.The LT4256-3 is available in a 16-lead SSOP package.Retry / Latch OffFeaturesPackageLT4256-1Latch OffUVSO-8LT4256-2RetryUVSO-8LT4256-3Latch Off or RetryUV/OV, Open Circuit DetectSSOP-16ApplicationsHot Board InsertionElectronic Circuit Breaker/Power BussingIndustrial High Side Switch/Circuit Breaker24V/48V Industrial/Alarm SystemsIdeally Suited for 12V, 24V and 48V Distributed Power Systems48V Telecom Systems

The LT4275 is a pin-for-pin compatible family of IEEE 802.3 and LTPoE++ powered device (PD) controllers.The LT4275A employs a proprietary LTPoE++ classification scheme, delivering 38.7W, 52.7W, 70W or 90W of power at the PD RJ45 connector. The LT4275A is fully compatible with IEEE 802.3. The LT4275B is an IEEE 802.3at compliant, Type 2 (PoE+) PD delivering up to 25.5W. The LT4275C is an IEEE 802.3af compliant, Type 1 (PoE) PD delivering up to 13W.The LT4275 internal charge pump provides an N-channel MOSFET solution, eliminating a larger and more costly P-channel MOSFET. A low RDS(ON)MOSFET also maximizes power delivery and efficiency, reduces power and heat dissipation, and eases thermal design. Startup inrush current is adjustable with an external capacitor. The LT4275 also includes a power good output, on-board signature resistor, undervoltage lockout, and thermal protection. The LT4275A/LT4275B drives a single opto-coupler to indicate the power level of the attached PSE. Pin-selectable support for non-standard low voltage operation is provided. Auxiliary power override is supported with the AUX pin.The LT4275A can be configured to support all possible LTPoE++, 802.3at and 802.3af power levels with external component changes.ApplicationsHigh Power Wireless Data SystemsOutdoor Security Camera EquipmentCommercial and Public Information DisplaysHigh Temperature Industrial Applications

The LT4276 is a pin-for-pin compatible family of IEEE 802.3 and LTPoE++ Powered Device (PD) controllers. It includes an isolated switching regulator controller capable of synchronous operation in both forward and flyback topologies with auxiliary power support.The LT4276A employs the LTPoE++ classification scheme, receiving 38.7W, 52.7W, 70W or 90W of power at the PD RJ45 connector, and is backwards compatible with IEEE 802.3. The LT4276B is a fully 802.3at compliant, 25.5W Type 2 (PoE+) PD. The LT4276C is a fully 802.3af compliant, 13W Type 1 (PoE) PD.The LT4276 supports both forward and flyback power supply topologies, configurable for a wide range of PoE applications. The flyback topology supports No-Opto feedback. Auxiliary input voltage can be accurately sensed with just a resistor divider connected to the AUX pin.The LT4276 utilizes an external, low RDS(ON)N-channel MOSFET for the Hot Swap function, maximizing power delivery and efficiency, reducing heat dissipation, and easing the thermal design.ApplicationsHigh Power Wireless Data SystemsOutdoor Security Camera EquipmentCommercial and Public Information DisplaysHigh Temperature Applications