Linear – Wide operating range ideal diode controller provides negative input protection (LTC4359)

Offering a simple low-loss replacement for Schottky diodes, and with key features aimed at automotive, avionics and solar applications, Linear Technology has introduced the LTC4359 high voltage ideal diode controller.

The LTC4359 operates over a wide 4V to 80V supply range and withstands input voltages between -40V to 100V without damage. Operating current is a low 150µA, and a shutdown control input enables the LTC4359 to be in a low current shutdown mode, drawing just 13µA. In addition, the LTC4359 is ‘guaranteed’ for operation across the -40C to 125C ambient temperature range. These features enable the LTC4359 to protect loads in harsh automotive environments such as during load dump, cold crank, two-battery jumps, and reverse battery connections. When combined with the LT4363 high voltage Surge Stopper, the LTC4359 provides solid front-end protection from over-voltage, over-current and reverse battery. Solar systems also benefit from the low operating current of this device, where the LTC4359 can be used to provide a low loss path that isolates the solar panel from the load.

The LTC4359 controls an external N-channel MOSFET to perform the function of a low forward voltage diode. This provides a lower loss path compared to Schottky diodes and in high power applications provides a more efficient solution and preserves precious board space by reducing the need for heat sinking. In addition, control of back-to-back MOSFETs is available to prevent current flowing from input to output during shutdown. The LTC4359 controls the forward voltage drop across the MOSFET to ensure smooth current delivery without oscillation, even under light loads. If a power source fails or is shorted, a fast <1µs turn-off minimizes reverse current transients.

The LTC4359 single ideal diode controller can also be used in applications where multiple power supplies are paralleled to provide redundancy. In N+1 redundant systems, an additional supply is added to safeguard the system in the event one of the supplies fail. ORing the supplies together allow disconnection from the power bus for an input failure or hard short. Additionally, the LTC4359 can be used with a reservoir capacitance to hold up the supply for a period of time after a loss of input power. This enables continuing system operation without resetting or rebooting due to brief interruptions of input power.

The LTC4359 joins a family of ideal diode controllers that includes the single high voltage LTC4357 ideal diode controller, LTC4355 positive diode-OR, LTC4354 negative diode-OR controllers, and the 0V-18V LTC4352 single ideal diode controller. The ideal diode controller portfolio complements Linear’s extensive portfolio of surge stoppers and Hot Swap controllers, such as the high voltage LTC4260 Hot Swap controller with an internal ADC for extensive system monitoring.

Specified over the commercial, industrial and automotive temperature ranges, the LTC4359 is offered in 2mm x 3mm 6-lead DFN and 8-lead MSOP packages, says the company.