KL25Z USB artifact issue

[karolina92]

Hi, I have FRDM KL25Z connected to expansion board FXS MULT2-B and together powered by battery. On KL25Z, I switched on LED diode (LED diode lights) . But when i connect usb to PC (or unconnected from PC) , the diode blinks once (caused by supply voltage temporarily drops from 3.3V to 1V, and then stabilizes at 3.1 V again). It is caused by time delay beetwen power supply from PC and battery power supply (or opposite way). I need eliminate this artifact or at least reduce. Knows someone, how to solve it? Thank you very much.kl25z frdm-fxs-mult2-b usb‌ artefacts

[jorge_a_vazquez]

Hi Karolina

I assume that you are using a Rev-D right? The temporarily drop of supply voltage is caused by a diode.

While you are supplying with P5_9V_Vin there is not diode, but when you connect USB to OpenSDA and it supply power to the system, you have a diode that cause a temporary drops of voltage. If you check schematic od Rev-E or F there is a diode in P5-9V_VIN. Also I have made a test of this and it only occurs in Rev-E schematic.

Hope this information helps you
Have a great day,
Jorge Alcala

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