Hi Unisoft
LED D8 is actually not used at all... this is some kind of LVP/UVP protection...
If the INPUT voltage will drop, the logic will start to decrease output voltage...
This function is not used and not implemented...
I want to see, when the LED D8 will light up so I decided to feed my RD6012 with minimum voltages.
Here my test results:
at 3,40V LED D8 flashes once (measured voltage on U3 is only 4,70V (instead 8,30V)).
3,50V to 3,80V LED D8 light up continuously (voltage on U3 is 8,30V).
3,90V to 4,10V LED D8 light up for 1-2sec
at 4,20V LED D8 light up for 1-2sec and displays shows Bootloader (maybe the voltage are to low on U8 (W25Q32JVSIQ) to read the FW from the memory?)
4,30V to 4,50V LED D8 light up for 1-2sec and Riden try to boot and crashes (maybe the same issue with low voltage on U8)
4,60V to 5,10V* LED D8 light up for 1sec, Riden boot normaly, but the ARM MCU crashes when turning on the output.
5,20V to 5,40V LED D8 doesn´t light up, only the display flickers once when turning on the output -> But everything works normally.
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It doesn´t make sense, if LVP/UVP use it for the internal components to protect them or what else.... because the last working components which works normally is
the ARM MCU itself, and only the MCU set the UVP thereshold voltage (connected to the positive input of the OP AMP (U8 - LM321).
It would make only sense if you use a transformer -> why, because they don´t have a regulated output voltage.
The MCU measure the idle input voltage and when the loaded input voltage are lower then for example 2V, the MCU will decrease the output voltage/current to protect the transformer.
It´s just my opinion.