Goliath Spring 2018 – Power Budget

By: Ryan Nguyen (MST Engineer)

Verified By: Ernie Trujillo (Project Manager)

Approved By: Miguel Garcia (Quality Assurance)

Figure 1 – Power Budget for the components of the Goliath.

Version 6.x of the 3DoT board does not include an LDO component, thus several changes were made to the power budget to reflect that change. All of LDO related currents and voltages were deleted, making the template much simpler. To calculate the power budget out the template, current draw of each subsystem must be obtained, by either measurement or data sheets. The template then takes those measurements and calculates the margins of power dissipation, output current, and how long the battery would last. Several assumptions were made, such as the EFFboost, the efficiency of the buck/boost converter, UVLO, FET switch limit, and inductor saturation.

Since Goliath does not use a servo, we won’t have a current draw from it. Regarding margins, there are three that we considered. From top to bottom and left to right: The first is heat safety margin. Our application dissipates 41.62 mW while the max is 971 mW so we are almost 96% safe. The second margin is the boost converter and its supply current margin; boost converter is able to supply plenty of current with a 91% margin. Third, is the margin is maximum instantaneous current the battery can supply, at 1300 mAH, we have a 78.46% margin. Lastly, we have a huge margin on runtime where we are able to operate at 112 minutes, twice the mission duration of 1 hour.