Dear friends,
I would like to share my experience or rather an accident that happened with WEMOS LOLIN32 development board. As I was experimenting with this new monster ( some of the results which i have shared earlier), I accidentally reversed the VCC (3.3V pin) and Ground connection to an OLED Display (probably I am getting old!). The result was that the LDO on board (ME6211-3.3) got damaged and the internal series pass MOSFET output somehow got permanently latched to 0.5V. This actually brings out a design compromise , the LDO does not have short circuit and thermal protection. A better LDO should have been used there.
However I removed the LDO completely and rigged up a quick and dirty fix by generating 3.3V by using a series combination of two 1N4148 diodes and deriving 5V from on-board supply (5V pin). This trick worked and now my LOLIN32 is functional( though I shall not be able to use the on-board Li-Po circuit and the diode combination can support upto 300mA only against the LDO with 500mA sourcing capacity)
The moral of the story is that the board can be easily damaged due to a short across 3.3V pin and ground. WEMOS should have made it a bit more robust.
My quick and dirty fix is visible in the attached image.
I would like to share my experience or rather an accident that happened with WEMOS LOLIN32 development board. As I was experimenting with this new monster ( some of the results which i have shared earlier), I accidentally reversed the VCC (3.3V pin) and Ground connection to an OLED Display (probably I am getting old!). The result was that the LDO on board (ME6211-3.3) got damaged and the internal series pass MOSFET output somehow got permanently latched to 0.5V. This actually brings out a design compromise , the LDO does not have short circuit and thermal protection. A better LDO should have been used there.
However I removed the LDO completely and rigged up a quick and dirty fix by generating 3.3V by using a series combination of two 1N4148 diodes and deriving 5V from on-board supply (5V pin). This trick worked and now my LOLIN32 is functional( though I shall not be able to use the on-board Li-Po circuit and the diode combination can support upto 300mA only against the LDO with 500mA sourcing capacity)
The moral of the story is that the board can be easily damaged due to a short across 3.3V pin and ground. WEMOS should have made it a bit more robust.
My quick and dirty fix is visible in the attached image.
). The picture corresponds to a half-built non-damaged one
