Low Voltage Power Supply Point Design

The Overview

As part of the NASA-Olin Summer Research Program, our team developed a low voltage power supply design for an unregulated 28V supply to fit the electrical and mechanical requirements of the XACT rocket system. Subsets of our system included supporting circuitry to measure and output voltage, current, and temperature readings from the power board and a graphical user interface through which users could set adjustable voltages. Our design implemented a 6-inch by 12-inch printed circuit board (PCB) that accounted for 15 DC-DC voltage converters, 6 adjustable voltages, and housekeeping subsystems for these components and the rocket battery. The adjustable voltages were controlled with a digital-analog converter that received user-specified voltages using I2C communication. Four analog multiplexers were used to read the housekeeping functions of the DC-DC converters, and operational amplifiers were used for the adjustable voltage setting. The housekeeping functions required supporting circuitry to attenuate values to a measurable value, with 2.2V corresponding to the expected values. Furthermore, a USB communication line was established using a programmable PIC 18F455 and a secondary printed circuit board to connect the digital-analog converter and multiplexers with the graphical user interface.

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