Analog Devices Inc./Maxim Integrated

The LT4322 is a floating active rectifier controller that drives an external N-Channel MOSFET to replace a rectifier diode. It is designed primarily for AC applications and operates with input supply frequencies ranging from DC to 100kHz. On each cycle of the input AC waveform, an external N-Channel MOSFET gate is enhanced to provide the equivalent of a low diode forward voltage drop of 25mV. The resulting reduction in power dissipation eliminates thermal design problems and costly heat sinks, greatly reducing PC board area.The addition of a high-voltage depletion N-Channel MOSFET enables operation at very high output voltages, limited only by the voltage ratings of two external MOSFETs. In AC applications, an integrated LDO provides the required gate drive voltage to turn the external MOSFET fully on. Fast, high-current gate drivers minimize reverse current transients at high input frequencies.APPLICATIONSSingle-Phase, 3-Phase, and 6-Phase Bridge RectifiersAutomotive Alternator Bridge RectifiersOff-Line Active Bridge Rectifier3-Phase Aircraft PowerHigh-Voltage DC Diode-OR with Reverse Blocking

The LT4351 creates a near-ideal diode using external single or back-to-back N-channel MOSFETs. This ideal diode function permits low loss ORing of multiple power sources. Power sources can easily be ORed together to increase total system power and reliability with minimal effect on supply voltage or efficiency. Disparate power supplies can be efficiently ORed together.The IC monitors the input supply with respect to the load and turns on the MOSFET(s) when the input supply is higher. If the MOSFET’s RDS(ON)is sufficiently small, the LT4351 will regulate the voltage across the MOSFET(s) to 15mV. A STATUS pin indicates the MOSFET on-state.An internal boost regulator generates the MOSFET gate drive voltage. Low operating voltage allows for ORing of supplies as low as 1.2V.The LT4351 will disable power passage during undervoltage or overvoltage conditions. These voltages are set by resistive dividers on the UV and OV pins. The undervoltage threshold has user programmable hysteresis. Overvoltage detection is filtered to reduce false triggering.The LT4351 is available in a 10-pin MSOP.ApplicationsParalleled Power SuppliesUninterrupted SuppliesHigh Availability SystemsN + 1 Redundant Power Supplies

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 LT4356-3 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 LT4356-3 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, until theSHDNpin pulls low momentarily.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. TheSHDNinput turns off the part, including the auxiliary amplifier, and reduces the quiescent current to less than 7µA.LT4356-1LT4356MP-1LT4356-2LT4356MP-2LT4356-3LT4356MP-3Low Current Shutdown7µa60µa7µaAux Amp In ShutdownOFFAlways AliveOFFFault RetryRetryRetryLatchoffPackagesDFN-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 Systems

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 LT4356MP 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 cooldown 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 Systems

The LT®4423 is a 1.9V to 28V ideal diode and load switch with integrated P-channel MOSFETs. When enabled, 15mV forward voltage regulation minimizes power dissipation while increasing operating headroom and efficiency compared to a Schottky diode.Using two LT4423s in diode-OR applications provide a seamless transfer to the highest available voltage under varying input supply conditions. A non-enabled LT4423 blocks up to 28V in either direction or polarity while exhibiting less than 1μA (typical) leakage current, providing orders of magnitude improvement over typical Schottky diodes, which leads to extended battery life.Fast OUT to IN reverse bias detection minimizes reverse current, preventing undesired charging of input batteries. The open-drain STATUS output pulls low when the LT4423 is in shutdown, reverse bias, or under thermal protection. Integrated thermal detection protects from overtemperature conditions by disabling the power path.APPLICATIONSSchottky Diode ReplacementBattery and Wall Adapter Diode ORingBackup Battery Diode ORingIndustrial and Consumer Hand-Held Applications