DEMO MANUAL DC2180A LTC4371 Dual Negative Voltage Ideal Diode-OR Controller Description Demonstration circuit 2180A showcases the LTC 4371 Design files for this circuit board are available at dual negative voltage ideal diode-OR controller and moni- DEMO MANUAL DC2180A Quick tart sDp Overview The short term current-carrying capability is limited by the MOSFET rating of 1200A pulsed at 25C case tem- DAnger HigH vOLTAge TeSTing SHALL be per - perature, gradually giving way to dissipation limitations fOrmeD by quALifieD perSOnneL OnL y. AS A SAfeT y for longer surges. Up to 100A load current can be easily preCAuTiOn AT LeAST T wO peOpLe SHALL be preSenT handled for one second. See the MOSFET data sheet for During HigH vOLTAge TeSTing. further information. DC2180A showcases the LTC4371 dual negative voltage The input voltage is limited by the BV rating of the DSS ideal diode-OR controller and monitor in a 48V, 50A MOSFETs to 100V. The MOSFETs can be driven into application. 2m maximum, 100V MOSFETs (M1 to M4) breakdown within the limits spelled out in their data sheet. are used (two per channel) to realize a full load drop of less than 50mV, and a loss of less than 2.5W. The LTC4371 V supply is regulated by an on-chip shunt DD regulator at the VZ pin, and biased by 30k series limiting board Layout resistor, R . Dissipation in R and R1 (bias resistor for LED Z Z D1) limit the maximum DC operating condition to about The board comprises four layers, with planes for 48VA, 90V. 85V is suggested as a conservative maximum 48VB, 48VOUT and RTN. These planes are replicated DC input voltage, leaving margin for elevated operating on each of the four layers to achieve the lowest possible temperatures and brief excursions up to the BV rating DSS resistance, minimize conduction loss and convey heat of the MOSFETs. away from the power MOSFETs. There are exposed conductors on the bottom of the High Current Connections board, and the heads of the cap screws protrude through Panduit S4-14R lugs are provided for connecting 50A the bottom of the board. The underlying surface should power supplies and a 50A load. The lugs are designed be non-conductive and clear of wire, solder and other for crimping to 4 AWG welding cable. A Thomas & Betts conductive debris. WT115 or equivalent crimper is suggested for the lugs. Other crimping methods can result in an inferior, high Current and voltage Limitations resistance and short-lived connection whose power dis- DC2180A is designed to deliver 50A continuous load sipation contributes significantly to board temperature rise. current from any combination of current at the 48VA The importance of properly sized cabling cannot be over- and 48VB inputs. If the current is concentrated in one stated. 4 AWG welding cable exhibits a resistance of 263 input, the two MOSFETs in that channel will dissipate a per foot. The cabling in a typical bench setup can easily total of slightly less than 2.5W. If the current is shared total 10 , producing a voltage drop exceeding 100mV and equally between both inputs the total dissipation falls to a power loss of more than 6W in the cable alone. Contrast 1.25W, since with all four MOSFETs conducting the total this with a voltage drop of 50mV and power dissipation resistance is effectively halved. of 2.5W total in the MOSFETs at 50A. dc2180af 2 ure roce