NPN on DFR0379 Buck Step Down is too spicy!
Levi.Baerg 2026-07-27 22:16:57 119 Views1 Replies Attempting to regulate 32 V on separate channels with the DFR0379 to output 30 V on purely resistive (220k) load. Current draw is ~80 mA per channel.
My issue is that the NPN transistor (D882) is getting too hot to touch. I plan to operate these with additional loads that may reach 100 mA.
Looking into the issue tells me that its the power the display! Diabling the display drops ~42 mA! This is seen on other boards too, so I want to ask if this is a bug or a feature? and will this affect the longevity of the board?
42mA for the display is definitely on the high side, but pretty common with these built-in digital display modules — the LED backlight and driver chip eat more than you'd expect. Not really a bug, more like a design tradeoff.
The D882 getting hot makes sense — at 32V in and 30V out, even with low current, that transistor is dissipating the voltage difference as heat. If you're gonna push it to 100mA continuously, I'd stick a small heatsink on it or lower the input voltage a bit. Running it hot long-term will shorten its lifespan for sure
Jason.Miao 