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https://gitlab.com/postmarketOS/postmarketos/-/issues/63
https://gitlab.postmarketos.org/postmarketOS/postmarketos/-/issues/63




== UART level-shifting ==
== UART level-shifting ==


https://gitlab.com/postmarketOS/postmarketos/-/issues/63#note_1941713275
https://gitlab.postmarketos.org/postmarketOS/postmarketos/-/issues/63#note_1941713275


* Options:
* Options:
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** A 12V-in barrel jack which powers a buck converter with ~3.8-9v 4A output. This will be used to power phones running without a battery
** A 12V-in barrel jack which powers a buck converter with ~3.8-9v 4A output. This will be used to power phones running without a battery
** A software-controllable way to adjust voltage on the buck converter
** A software-controllable way to adjust voltage on the buck converter
TODO: add caleb's off the shelf integrated one?
TODO: Ask Luca about FP2 mobo project that also replaces battery


=== LT3690 ===
=== LT3690 ===

Latest revision as of 18:42, 3 February 2025

https://gitlab.postmarketos.org/postmarketOS/postmarketos/-/issues/63


UART level-shifting

https://gitlab.postmarketos.org/postmarketOS/postmarketos/-/issues/63#note_1941713275

Pi Zero Socket

Buck Converter

  • Requirements
    • A 12V-in barrel jack which powers a buck converter with ~3.8-9v 4A output. This will be used to power phones running without a battery
    • A software-controllable way to adjust voltage on the buck converter

TODO: add caleb's off the shelf integrated one?

TODO: Ask Luca about FP2 mobo project that also replaces battery

LT3690

To change the voltage, we need to change the resistance (See page 12). To meet requirements, we need to change the resistance in the resistor network which can be done using a digital potentiometer:

https://www.analog.com/media/en/technical-documentation/data-sheets/AD5293.pdf

To ensure voltage output is accurate, make sure tolerance of pot is 1%.

https://en.wikipedia.org/wiki/Digital_potentiometer#Limitations

TODO: research disadvantages of digital pot