Circuit diagram for typical FC power supply?

Is there a link or any info on the typical power supply circuit used in 1S flight controllers? I assume it’s somewhat generic, 5v booster circuit and then 3.3v regulated off that?

I feel like if I could identify the components that are involved it would make it easier to diagnose/repair. I’m guessing it’s a fairly generic circuit?

Right now I have a Betafpv Lite FC V2.0 where the camera suddenly shorted out mid-flight. It no longer produces 5v output, but it does fly without a camera. I have some Mt3608 regulator chips from another repair, but it seems that chip wasn’t the problem (that must be the 3.3v regulation chip).

I would expect If it’s a decent board you could work it out from the inductor; Work backwards from the pads, trace back to the inductor which I think would be connected to a decently sized capacitor and then to a step up regulator.

Ah see I am not electronically trained. I can follow electrical diagrams and check for blown components, but even just saying step up regulator, I’m not sure what I am looking for. I was convinced the mt3608 was the 5v step up regulator (I had some of those because that chip was actually knocked off my fc at some point and betafpv informed me that was the booster chip). But when I check the output leg of that chip, it’s only showing 3.34v (that’s after replacing it). It also gets pretty damn warm after a few seconds, so I’m guessing there might be something else blown… No visual damage to any components though


Mt3608 on the left side which I replaced. The inductor is on the underside of the fc… So I guess the regulator or booster is the 5 leg chip near that inductor?

Was I correct in the 5v boost followed by a 3.3v regulation? And if so is there a basic diagram I could see to try and learn?

I need to head to bed (3am here) but hoping to learn something out of this fc

From my rudimentary knowledge of circuit design boards, I would expect on this 1s board that the mt3608 (I can’t see the writing on the top of it) is for dedicated 3.3v for all the MCU and chips, such as the gyro, STM32F0, radio, LEDS etc. The 5v for the VTX and camera should be separate for that, to keep the feed clean, so there would be a 5v booster that is coupled with the inductor and a few passives. So, that’s why everything else works fine and you have no 5v. It’ll take voltage straight from battery, ignoring the 3.3v from the other feeding regulator.

If you find the 5v regulator, find the number on it and we can track down the datasheet and check the pins for Vin and Vout

From my even more rudimentary knowlege I am going to assume that the regulator is one of the 2 5 pin chips on the bottom of the fc (second pic). The one on the top is underneath the 5v pad and camera plug. It’s marked SQ2JJ. But the closest match I found was Sq2hk which is a 3.3v reg. Also it’s so far from the inductor… There is that little 5pin next to the inductor too, my best smartphone magnification comes up with Sma47? But no results on that
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I should do some electronics study. It’s something I’ve always been interested in (I like logical stuff like computer programming)

Couldn’t really find anything on those markings but typically, the top left pin would be Vout and bottom left, Vin. So you could test the voltage of those with a multimeter. Find a ground (I think the middle bottom pin could be ground, they normally are in other regulators) and check voltage of bottom left pin. It should be battery voltage or 3.3v. If that’s fine, then check the top. You’ll know if it is that component.

Does it provide 5v if you puwer the board with a USB cable? If it does that will also confirm the step up is kaput

Good point. I will have to flash a different firmware onto it, the current one is designed to put the FC into DFU as soon as you plug in a USB.

Also realised i have a non-broken Lite FC that i could compare things with. I was hoping that i would see an obvious sign of blown components, but nothing jumps out at me.

I will also ask Betafpv if they would share the circuit diagram of the power circuit… Its worth a try