I wanted to power my new raspberry 4B with a D36V50F5 and since the beginning the Rpi warn with the “low voltage warning” and a reduced processor capacity
Setup is Rpi board (with keyboard+mouse) and a 15.6 inch uperfect monitor.
Both are normally powered with 5v3A wallplug.
As the maximum continuous output current graph indicate 8Amps for an 13v input, I guess that the problem does not come from a over current demand as maximum current taken by the Rpi/screen combo is 6Amps.
Vout and gnd are wired to two standard female usb socket (very short wire and 12awg) and then two standard USB cable USB male/type c male plug between regulator and rpi/screen
Either the cable and connection lead a loss or the D36V50F5 do not succeed to handle the variation of current required by the setup and lead the voltage to drop under 4.65v.
In the last case, the only solution I see is to insert capacitor between Vout en Gnd.
Could you please confirm this solution can work and give me a µF value that will maybe solve the problem ?
Seems like you have a few amps passing through each of your USB-C cables, which it probably near their limit, so I would not be surprised to see a drop in voltage across them. You should measure the voltage at VIN and VOUT on the regulator and at the input of your Raspberry Pi.
Adding a capacitor near the input to the RPi could help if the issue is quick drops in the voltage from surges in current. A capacitor will not help if the issue is the constant draw through the cables causing too large a drop. Either way though, trying a capacitor should not damage anything. Something around 100uF should be a good value to try.
Thank you for your answer,
Yes, such as your assumption a bad cable and bad quality plug was causing a voltage drop and the causes of my “low voltage warning” message.
I keep the capacitor value for a potential project when power variation will maybe require this capacitor.