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# <a name="LV2&#39;s Avionics Power System"></a> LV2's Avionics Power System

<table border=1 cellpadding=0 cellspacing=0>
  <tr>
    <th bgcolor="#99CCCC"><strong> Up: </strong></th>
    <td>[[AvionicsTeamHome]]</td>
  </tr>
  <tr>
    <th bgcolor="#99CCCC"><strong> Xref: </strong></th>
    <td align="right">[[BatteryPackLv2]], [[AandTBatteriesLv2]], [[PowerUseageLv2]]</td>
  </tr>
</table>

## <a name="Introduction"></a> Introduction

The Avionics Power System (APS) provides power and load switching to the avionics system. It has:

- A 14.4V (max 16.8V) 4Ahr (4s4p) [[Lithium Ion battery pack|BatteryPackLv2]] which includes a charge counter and voltage monitoring.
- A Li Ion battery charger based on the Linear Technologies LTC4007, which includes shore power current limiting.
- An interface to the umbilical cord for shore power to charge the batteries or run the avionics system, as well as to assert an ignition interlock with the launch tower called "rocketready".
- An "active diode" controller to switch between the battery and shore power.
- Four power switches to switch various vehicle systems on and off, e.g. RF power amplifiers, flight computer, etc.
- A 5V SPS with a linear bypass for for low power standby
- A [[PIC18F458]] microcontroller to control the system and interface it to the CAN bus.

The current version of the APS is v0.6, which was fabbed by PCBexpress 2004/09/08 and finished 2004/09/19.

Documents with a v0.7 number imply they were updated after the APS was fabbed and thus contain errata and future notes.

A [[previous version of the APS|CanNodeSectionAppPower]] used a PIC with a single parallel set of International Rectifier IPS5451 intelligent power switches and primary Lithium battery. The board was pretty simple, and then was hacked to death, and the primary Lithium batteries turned out to have only 1/8 of the energy we needed for flight.

## <a name="APS Information"></a> APS Information

- [[Engineering Notes for APS v0.7|AvionicsPowerSystemLv2/APS_BAT-Components.pdf]]
- [[APS-specific schematic (pdf) created from xfig; includes battery board connections but not SPS|AvionicsPowerSystemLv2/LV2-APS_BAT.pdf]]
- [[APS v0.6 schematic (pdf) created from the final EAGLE schematic|AvionicsPowerSystemLv2/APS_06_schematic.pdf]]
- [[APS v0.6 schematic and board layout (eagle) in a ZIP file|AvionicsPowerSystemLv2/aps_0.6.zip]]

- For the battery board schematics and board files, see [[BatteryPackLv2]]

- [[PowerUseageLv2]] - Power calculations based on LV2 loads

- The PIC firmware for the APS can be found at <http://cvs.psas.pdx.edu/c/firmware/aps/>. In particular, see the aps\_exports.h file for information on the APS' CAN messages

## <a name="APS Discussion"></a> APS Discussion

We're in process of calibrating the APS node: [[AvionicsPowerSystemLv2Calibration]]

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**_Old links:_**

[[ChargerIcResearchLv2]] - research into charging ICs for Li-Ion/Li-Polymer batteries<br />[[BatteryResearchLv2]] - research into Li-Ion/Li-Polymer batteries for LV2

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