DC1741A Analog Devices

DEMO MANUAL DC1741A LTC4370 Two-Supply Diode-OR Current Balancing Controller DESCRIPTION Demonstration circuit DC1741A features the LTC4370, a set of features to support shared current diode-ORed ap- two supply diode-OR current sharing controller in a typical plications including: 2.9V to 18V, 16A sharing application. Load Sharing Between Two Supplies The maximum MOSFET voltage drop V = V OUT is FR IN Elimination of the Need for Active Control of Input set with an external resistor, up to 600mV. A fast gate Supplies turn-on reduces the load voltage droop during supply Elimination ofShare Bus switchover. If the input supply fails or is shorted, a fast turn-off minimizes the transient reverse current. Reverse Current Blocking Disabling the load sharing function turns the LTC4370 Elimination of Shoot-Through Current During Start-Up into a dual ideal diode controller. or Faults Two enable input pins, EN1 and EN2, allow enabling and Design files for this circuit board are available at disabling each rails MOSFET individually while the MOS- DEMO MANUAL DC1741A OPERATING PRINCIPLES The LTC4370 controls N-channel MOSFETs, M1 and Two LEDs, OFF1 and OFF2, indicate the MOSFETs status. M2, to share the load between two input rails.The error Each LED lights up, when the gate voltage is less than amplifier compares OUT1 and OUT2, and controls servo 0.7V above V . IN amplifiers which regulate MOSFET forward voltage drop Pay special attention to the power supply features used to V . Combined action of the error amplifier and servo FR with the LTC4370. amplifiers forces OUT1 and OUT2 to be equal and as a This controller may not work properly with supplies utilizing result the rail currents are equal. The board RANGE resistor synchronized rectification in the output stage unless the R3 = 30.1k defines maximum regulation voltage range as internal circuit of the supply has the ability to limit negative 265mV to 375mV. current or to block it completely. Exercise caution when The board is assembled with SUM85N03-06P N-channel using the controller with this type of supply unless it is MOSFETs, which in a single channel application has determined that it contains the required circuitry. current capability up to 20A. In the load share mode the installed components guarantee continuous proper load sharing up to 16.6A total load. For a short test time of 3 to 5 seconds it is possible to double this load. dc1741af 2