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• Digital IC Selection

  • EG915NEAAC-N05-SNNSA

    • Supports NA

    • Supports max mavlink datarate

    • no external camera features keeps cost down

    • ~$30 bucks

    • Optional GPs port that is uses. Will use a u.fl connector and an onboard antenna we can choose between.

  • STM32F415RGT6

    • has USB FS support and a ton of UARTs

    • $18 is a lot but it’s the cheapest we gonna get

  • somewhat discussed in LTE Breakout

    • STM32 pinout given in Discord conversations

• First Buck Stage Component Searching

  • Super glad there’s a lot of options in this voltage range, seems to be getting better with time as automotive bus voltages are rising.

  • Best from MPS

    • https://www.monolithicpower.com/en/mp4575.html

    • https://www.digikey.ca/en/products/filter/voltage-regulators-dc-dc-switching-regulators/739?s=N4IgTCBcDaILIAUAsBWA7CkBdAvkA

    • I kinda wanted to use MPS here, but doesnt seem like any of their stuff solves

  • Searching Digikey

    • https://www.digikey.ca/en/products/filter/pmic/voltage-regulators-dc-dc-switching-regulators/739?s=N4IgjCBcoBwOxVAYygMwIYBsDOBTANCAPZQDaIAzAJwBsNArCALqEAOALlCAMrsBOASwB2AcxABfQmABMVRCBSQMOAsTIhZFONIAsIQtp06IhGDRjSazNp0g9%2BwsZJD04FeYuV5CJSOTAADAE0cCYaOtT0VoS6NGAU7jE6NFRUYdKuNDrS%2Bhr0MNRyMfS02bmWFAFUMOVwxoG1MGBmjTD06fA0WrmVlnA1hCk0srmhFBG5MNkwRSBUOnD51iAcXLyCohJSVTXQCmhY3mp%2BlNIUcQgsK7b2G05S1XJ7noeqvuQBzM4AtDnPUPwAK5vdSMJg-J7IAF8YE%2BdQQcHOKx7AQAEy430CORsXFy7AAnqxcFxUdgUOJxEA

    • I like these microchip and Vishay options, the analog devices ones are hella overpriced (as usual).

    • Microchip options are slightly cheaper and support higher input voltage so will let one of these ride.

    • Plenty in stock, super cheap, https://www.digikey.ca/en/products/detail/microchip-technology/MIC28516T-E-PHA/13175035 seems like the way to go here! Size doesn't really matter that much for me. Way smaller then having external FETs so I’ll take it.

      • MIC28516T-E/PHA

      • Datasheet Rev A: https://ww1.microchip.com/downloads/en/DeviceDoc/MIC28516-70V-8A-Hyper-Speed-Control-Synchronous-DC-DC-Buck-Regulator-with-External-Soft-Start-DS20006315A.pdf

      • Datasheet Rev D: https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MIC28516-Data-Sheet-DS20006315.pdf

  • Setting output voltage to 5.05V target, calculating using https://github.com/UWARG/hardware/tree/master/Scripts.

Layout

Collection of hardware design guideline excerpts from various component datasheets.

Quectel_EG915N_Series_Hardware_Design_V1.2.pdf

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Modem Re-Selection

We initially selected the EG915N-EA, which only includes bands optimized for usage in Europe and Asia.

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Model/Specs	EG915N-EA (original model)	BG95M3 Series	EG915Q-NA Series
LTE Bands	LTE-FDD: 1 / 3 / 7 / 8 / 20 / 28	Cat M1: 1 / 2 / 3 / 4 / 5 / 8 / 12 / 13 / 18 / 19 / 20 / 25 / 26 / 27 / 28 / 66 / 85 Cat NB2: The above and 71	LTE-FDD: 2 / 4 / 5 / 12 / 13 / 66 / 71(?)
# of SIM Interfaces	2	1	2
Screenshot

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Layout

Collection of hardware design guideline excerpts from various component datasheets.

Quectel_EG915N_Series_Hardware_Design_V1.2.pdf

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