Analog Devices

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

The LT4293 is an LTPoE++/IEEE 802.3af/at/bt-compliant powered device (PD) interface controller. The T2P output distinguishes between LTPoE++ and IEEE 802.3bt power sourcing equipment (PSE) during mutual identification and negotiation of available power.The LT4293 utilizes an external, low RDS(ON), N-channel, hot swap MOSFET and supports the LT4320/LT4321 ideal bridges, to extend the end-to-end power delivery efficiency and eliminate costly heat sinks. The LT4293 also includes a power good output, onboard signature resistor, undervoltage lockout, and thermal protection. Start-up inrush current is adjustable with an external capacitor. Auxiliary power override is supported as low as 9V with the AUX pin.The LT4293 can be configured to support all possible LTPoE++, 802.3bt, 802.3at and 802.3af power levels with external component changes. Pin-for-pin compatibility with the LT4275 and LT4294 family of PD Interface Controllers enables easy migration between LTPoE++ PDs and IEEE 802.3bt-compliant PDs.ApplicationsHigh Power Wireless Data SystemsOutdoor Security Camera EquipmentCommercial and Public Information DisplaysHigh Temperature Industrial Applications

The LT4294 is an IEEE 802.3af/at/bt-compliant powered device (PD) interface controller. TheT2Poutput indicates the number of classification events received during IEEE 802.3bt-compliant mutual identification and negotiation of available power.The LT4294 utilizes an external, low RDS(ON)N-channel hot swap MOSFET and supports the LT4320/LT4321 ideal diode bridges, to extend the end-to-end power delivery efficiency and eliminate costly heat sinks. The LT4294 also includes a power good output, onboard signature resistor, undervoltage lockout, and thermal protection. Start-up inrush current is adjustable with an external capacitor. Auxiliary power override is supported as low as 9V with the AUX pin.The LT4294 can be configured to support all possible 802.3bt, 802.3at and 802.3af power levels with external component changes. Pin-for-pin compatibility with the LT4275 family of PD Interface Controllers enables easy migration between LTPoE++ PDs and IEEE 802.3bt-compliant PDs.ApplicationsHigh Power Wireless Data SystemsOutdoor Security Camera EquipmentCommercial and Public Information DisplaysHigh Temperature Industrial Applications

The LT4295 is an IEEE 802.3af/at/bt-compliant powered device (PD) interface controller with a switching regulator controller. The T2P output indicates the number of classification events received during IEEE 802.3bt-compliant mutual identification and negotiation of available power.The LT4295 supports both forward and flyback power supply topologies. The flyback topology supports No-Opto feedback. Auxiliary input voltages can be accurately sensed with just a resistor divider connected to the AUX pin.The LT4295 utilizes an external, low RDS(on)N-channel hot swap MOSFET and supports the LT4320/LT4321 ideal diode bridges, to extend the end-to-end power delivery efficiency and eliminate costly heat sinks.The LT4295 also includes an on-chip detection signature resistor, thermal protection, slope compensation, and many user configurable settings including classification signature, inrush current, switcher frequency, gate drive delay, soft-start and load compensation.ApplicationsHigh Power Wireless Data SystemsOutdoor Security Camera EquipmentCommercial and Public Information DisplaysHigh Temperature Applications

The LT4320/LT4320-1 are ideal diode bridge controllers that drive four N-channel MOSFETs, supporting voltage rectification from DC to 600Hz typical. By maximizing available voltage and reducing power dissipation (see thermograph comparison below), the ideal diode bridge simplifies power supply design and reduces power supply cost, especially in low voltage applications.An ideal diode bridge also eliminates thermal design problems, costly heat sinks, and greatly reduces PC board area. The LT4320’s internal charge pump supports an all- NMOS design, which eliminates larger and more costly PMOS switches. If the power source fails or is shorted, a fast turn-off minimizes reverse current transients.The LT4320 is designed for DC to 60Hz typical voltage rectification, while the LT4320-1 is designed for DC to 600Hz typical voltage rectification. Higher frequencies of operation are possible depending on MOSFET size and operating load current.ApplicationsSecurity CamerasTerrestrial or Airborne Power Distribution SystemsPower-over-Ethernet Powered Device with a Secondary InputPolarity-Agnostic Power InputDiode Bridge Replacement

The LT4356 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET. The output is limited to a safe value thereby allowing the loads to continue functioning. The LT4356 also monitors the voltage drop between the VCCand SNS pins to protect against overcurrent faults. An internal amplifier limits the current sense voltage to 50mV. In either fault condition, a timer is started inversely proportional to MOSFET stress. If the timer expires, theFLTpin pulls low to warn of an impending power down. If the condition persists, the MOSFET is turned off. After a cool down period, the GATE pin pulls up turning on the MOSFET again.The auxiliary amplifier may be used as a voltage detection comparator or as a linear regulator controller driving an external PNP pass transistor.Back-to-back FETs can be used in lieu of a Schottky diode for reverse input protection, reducing voltage drop and power loss. A shutdown pin reduces the quiescent current to less than 7µA for the LT4356-1 during shutdown. The LT4356-2 differs from the LT4356-1 during shutdown by reducing the quiescent current to 60µA and keeping alive the auxiliary amplifier for uses such as an undervoltage lockout or always-on regulator.LT4356-1LT4356MP-1LT4356-2LT4356MP-2LT4356-3LT4356MP-3Low Current Shutdown7uA60uA7uAAux Amp In ShutdownOFFAlways AliveOFFFault RetryRetryRetryLatch OffPackagesDFN-12, MS-10, SO-16DFN-12, SO-16DFN-12, MS-10, SO-16Temp GradesC, I, H, MPC, I, H, MPC, I, H, MPApplicationsAutomotive/Avionic Surge ProtectionHot Swap/Live InsertionHigh Side Switch for Battery Powered SystemsIntrinsic Safety Applications

The LT4363 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, by controlling the gate of an external N-channel MOSFET. The output is limited to a safe value allowing the loads to continue functioning. The LT4363 also monitors the voltage drop between the SNS and OUT pins to protect against overcurrent faults. An internal amplifier limits the voltage across the current sense resistor to 50mV. In either fault condition, a timer is started inversely proportional to MOSFET stress. Before the timer expires, theFLTpin pulls low to warn of an impending power down. If the condition persists, the MOSFET is turned off. The LT4363-1 remains off until reset whereas the LT4363-2 restarts after a cool down period.Two precision comparators can monitor the input supply for overvoltage (OV) and undervoltage (UV) conditions. When the potential is below the UV threshold, the external MOSFET is kept off. If the input supply voltage is above the OV threshold, the MOSFET is not allowed to turn back on. Back-to-back MOSFETs can be used in lieu of a Schottky diode for reverse input protection, reducing voltage drop and power loss. A shutdown pin reduces the quiescent current to less than 7μA during shutdown.ApplicationsAvionic/Industrial Surge ProtectionHot Swap™/Live InsertionHigh Side Switch for Battery Powered SystemsIntrinsic Safety Applications

The LT4430 drives the opto-coupler that crosses the galvanic barrier in an isolated power supply. The IC contains a precision-trimmed reference, a high bandwidth error amplifier, an inverting gain of 6 stage to drive the optocoupler and unique overshoot control circuitry.The LT4430’s 600mV reference provides ±0.75% initial accuracy and ±1.25% tolerance over temperature. A high bandwidth 9MHz error amplifier permits simple frequency compensation and negligible phase shift at typical loop crossover frequencies. The opto-coupler driver provides 10mA of output current and is short-circuit protected. A unique overshoot control function prevents output overshoot on start-up and short-circuit recovery with a single capacitor.The LT4430 is available in the low profile 6-lead TSOT-23 package.Applications48V Input Isolated DC/DC ConvertersIsolated Telecommunication Power SystemsDistributed Power Step-Down ConvertersOffline Isolated Power SuppliesIndustrial Control SystemsAutomotive and Heavy Equipment

The LT5400 is a quad resistor network with excellent matching specifications over the entire temperature range. Matching is also specified when the LT5400 is configured in a difference amplifier. This enhanced matching specification guarantees CMRR performance to be up to 2× better than independently matched resistors.All four resistors can be accessed and biased independently, making the LT5400 a convenient and versatile choice for any application that can benefit from matched resistors.These resistor networks provide precise ratiometric stability required in highly accurate difference amplifiers, voltage references and bridge circuits.The LT5400 is available in a space-saving 8-pin MSOP package, and is specified over the temperature range of –55°C to 150°C.ApplicationsDifference AmplifierReference DividerPrecision Summing /Subtracting