Low Voltage Power Supply Project

LVPS Brick (DC/DC Converter Module)

The key component of the LVBOX is a small size (80 x 80 x 30mm), radiation and magnetic field tolerant, single output DC/DC dual transistor synchronous forward converter based on LT1681 chip. Full custom design using only COTS (Commercial Off The Shelf) components and the universal printed circuit board design enabled to select three brick versions of various outputs (+3.3V, +5V, or 15V) by means of only several components change. Brick input voltage is +200VDC. The maximum output power from the brick is 150W. The DC/DC converter design enables high efficiency of energy conversion: 72% for 3.3V @10A Iout, 85% for 5V version @10A, and 82 % for 15V version @6A, respectively. Switcher uses the current mode control and has fixed switching frequency of 300kHz. Important brick features are active Over current and Overvoltage protection circuitry. Innovative technology of brick cooling (the switching FET power transistors, power inductors and high frequency transformer) was applied by means of custom made Al2O3 ceramic spacers. In total, 2700 bricks including spares are needed for LVBOX production. Brick has integrated remote control and measurement circuitry for both input (Iin/Vin) and output (Iout/Vout) parameters. Moreover, three temperature sensors are also present to control brick cooling. Vout voltage can be trimmed in range of 15%. Brick can work in a radiation environment up to 20krad, and in external DC magnetic field of 200Gauss without problems.