Difference between revisions of "PinePhone 1.1 VBUS power usage Hardware Fix"
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This page details a hardware fix for an issue that affects some early [[PinePhone#Hardware_revisions | PinePhone]] units, namely [[PinePhone v1.1 - Braveheart | v1.1 Braveheart]] units (fixed since [[PinePhone v1.2 | 1.2 community edition]] included). | This page details a hardware fix for an issue that affects some early [[PinePhone#Hardware_revisions|PinePhone]] units, namely [[PinePhone v1.1 - Braveheart|v1.1 Braveheart]] units (fixed since [[PinePhone v1.2|1.2 community edition]] included). | ||
The issue was [[PinePhone_v1.1_-_Braveheart#Excess_power_usage_while_driving_VBUS | originally reported here]] by megi. | The issue was [[PinePhone_v1.1_-_Braveheart#Excess_power_usage_while_driving_VBUS | originally reported here]] by megi. | ||
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* [https://xnux.eu/devices/pp-pmic-fix.jpg Tutorial from megi] | * [https://xnux.eu/devices/pp-pmic-fix.jpg Tutorial from megi] | ||
* [https://xnux.eu/devices/feature/anx7688.html Description from megi] at the end of the page | * [https://xnux.eu/devices/feature/anx7688.html Description from megi] at the end of the page | ||
[[Category:PinePhone]] | |||
Latest revision as of 03:13, 16 March 2023
This page details a hardware fix for an issue that affects some early PinePhone units, namely v1.1 Braveheart units (fixed since 1.2 community edition included).
The issue was originally reported here by megi.
TODO: Add more pictures and schematics, better reference the fix origin and tradeofs, remove TODOs/FIXMEs.
Affected Units
FIXME: confirm "Project Don't Be Evil" devkit and PinePhone v1.0 - Developer batch are unaffected.
Disclaimer
Though easier to perform than the PinePhone 1.2 VCONN Hardware Fix, this fix requires desoldering relatively small Surface Mount Technology (SMT) components, therefore some experience with soldering is recommended.
Issue description
TODO: pictures
The AXP803 cannot detect when the USB port is powered by the battery. Therefore, the Power Management IC (PMIC) continues draining current from it. This is especially problematic since this USB port is powered from the battery with the USB OTG boost regulator. One of the symptoms is the battery discharging rather quickly even when the phone is powered off.
Workaround
HW workaround is desoldering the U1301 regulator (TODO: describe its role) and shorting pads for R1309 on the PCB (this is a "0 ohm" resistor on the schematic, so it's completely fine).
Shorting the pads is easy to do with some solder (while carefully avoiding to short it with nearby resistors).
Desoldering the regulator is harder to do, since its large pads are designed to use the PCB as a heatsink and will happily cool down while you are trying to melt it. It should be possible to use properly sized pliers to cut the pins first, please edit if you attempt this.
Please be careful not to overheat nearby components trough the PCB traces when applying heat to the regulator. It can be helpful to start the operation with melting some leaded solder tin together with the pads, and lifting the regulator while applying heat also helps. Start with the side that has only one pad: though it is bigger, it should be easier to lift up. It might be useful to apply a relatively large quantity of molten solder tin to each pin, in turn, while lifting the regulator, to reduce the PCB heatsink effectiveness.
Feel free to add your experiences and tips here.
Tradeoffs
TODO: Unknown to the author
Proper fix
TODO
Sources and tutorials
- Tutorial from megi
- Description from megi at the end of the page
