Backplane PCB
Overview
This board will be distribute power to all systems. It will take in the battery voltage, currently thinking this may be a 6S Lipo (22.2V). This board will have the following power busses:
- Vin (22.2V) → 12V Power Bus → Capacitor banks → Fuses → Distribution
- Vin → 9V Power Bus → Capacitor banks → Fuses → Distribution
- Vin → 5V Power Bus → Capacitor banks → Fuses → Distribution
Vin → 3.3V Power Bus- All power buses must have capacitor banks, fusing, zener protection and status lights
- ESC Power Bus → There must be capactor banks near the the placement of the ESC carrier boards. Also there is a heavy inductive loading from the motors so need to look in to some additional backEMF protection
- Must have a plugin for the ESC boards and provide power to them. Also must rout PWM and Dshot to the hardware board.
- Routes wires from leak detection sensor to Hardware board
- Have power connection ports on all busses (must be able to plug in jetson, ethernt switch, and other hardware external to the stack). Also add lots of extras for expansion
- Need bench testing power in port for when we do not want to use batires or want to swap out a battier bank with out having to power down the AUV. May possabiy want to add some protection to this?
The backplane will also need to hold the Pi Hat and 2X ESC carrier boards. These two systems will be contented through the the backplane, bolted inplace. Must make sure that the high speed traces have appropriate ground plane coverage.
Kill switch circuit To meet the kill switch requirements, we will have an isolated bus that provides power to the RP2040s on the ESC carrier boards. This BUS will be briged to the main 5V bus with a n-chanle mosfet. This mosfet will be triigered on/off from a magnetic read switch or a light gate. Cutting power here will isolate the ESCs from our system
Part Links
- https://www.digikey.com/en/product-highlight/f/flex-power-modules/pke7000a-8000a-series-ultra-wide-dc-dc-converters
- https://www.digikey.com/en/products/detail/murata-power-solutions-inc/UWE-5-15-Q12N-C/2345522
- https://www.digikey.com/en/products/detail/flex-power-modules/PKE8411API/10287602
- https://flexpowermodules.com/resources/fpm-techspec-pkj7200w , https://www.digikey.com/en/products/detail/flex-power-modules/PKJ7213WPI/16591121?s
Resources
- https://www.microtype.io/designing-power-mosfet-circuits/
- http://cdn-reichelt.de/documents/datenblatt/A400/SMD1N400%23DIO.pdf
Notes on input:
Need to figure out what the instance of our source is, but since everything is so tight is is hard to imaingen it is very high. Should add the decoupling capacitor either way though.
External Decoupling Capacitors on the load
We must add external decoupling capacitors on the load of the bricks. Make sure the ESR is in spec
??? I do not totaly understand how this works??
See Vin --> C_out relationship table. It looks like we should design so it is good for as low as 24V and only populate what we need for 48V in.
On the output it specifies capacitor banks between 0 and 3000 uF. Does this mean that we want to