Electronic Power Supply Unit (EPS)

The satellite will generate its own power with solar panels and will store the energy using two Li-Ion battery packs for operations during eclipse. The power supply architecture is presented in the diagram bellow.

GOLIAT's EPS

The satellite power is provided by the solar panels to a step-up DC to DC converter that increases the voltage on the line to approximately 9 V. The 9V line is used for battery pack charging and as a back-up line to power the satellite when the batteries are depleted.

The deployment (separation) switch and the Remove Before Flight switch are serially connected on the output line. No voltages are present on the power bus while either the Launch switch or the RBF switches are pressed (RBF pin present, satellite is in the P-POD).

While no external power supply is present and either of the two switches are in the ON position (satellite is in the P-POD or the RBF is present) the only components that are powered by the battery packs are: 4 UVLO (internal to the battery packs - might contain additional very low power circuitry), 2 diodes, 10 resistors, 4 MOSFETS, 4 capacitors.

When an external power supply is present all the circuitry up to the switches are powered to charge the batteries.

The voltage from the switches is connected to the voltage regulators, which on their turn supply the power bus.

When the USB data cable is present the battery is charged from the 5V voltages presented on that line. The 3.3 V line is supplied from the USB line as well to power the microprocessors during the debug mode. During the debug mode an external 5 V input supplies the 5 V line on the power bus for checking the health of the subsystems that require that voltage.

 
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