The MAX5079 evaluation kit (EV kit) demonstrates the
functionality of the MAX5079 ORing MOSFET controller
in a parallel-connected power-supply system. The EV
kit circuit is configured to connect two power supplies
in parallel using ORing MOSFETs to simulate a fault
condition, and to depict the isolation of the bus during
the fault condition. The EV kit is configured for 3.0V to
12.6V input operation. The external undervoltage-lockout
threshold is configured to 3.0V, and the overvoltage
threshold is configured to 13.2V. Operation down to 1V
is possible with circuit reconfiguration and an additional
auxiliary power supply. The MAX5079 controller, along
with an n-channel MOSFET, provides the functionality of
a diode with an extremely low forward-voltage drop.
The MAX5079 controllers on the EV kit monitor the
respective input voltages at VIN1 and VIN2 with respect
to the power bus voltage VBUS. When the VIN_ voltage
rises above the VBUS voltage, the MOSFET is quickly
turned on. If either VIN_ power-supply voltage falls below
VBUS, the MAX5079 discharges the MOSFET gate with
2A (typ) sink current and turns off the MOSFET within
200ns (typ), effectively isolating the bus.
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