I did a workshop on SMT today and we made this board attached. However, what I don’t understand completely is the logic: why do we need 3 resistors to increase the voltage (on the boost part)? What do they do exactly?
closed as unclear what you're asking by Edgar Brown, Andy aka, Elliot Alderson, laptop2d, Finbarr Jan 1 at 11:40
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It's an SMT practice board. ALL of the resistors are 10k, probably because whoever's running the course didn't want to have to stock different values. Therefore, to get a value of 30k, they put three in series.
Sometimes, multiple SMT resistors are put in series for high-voltage circuits because their individual voltage ratings are insufficient. But that isn't an issue in a circuit that outputs 5.5V at most.
BTW, before you reflow the board, you should flip over the resistors that are showing the white side up. It makes no difference functionally, but it makes it easier to inspect the board afterward.
I guess you are on about R4,5,6 on the boost converter ?? if so I would think this is a fed back circuit to make sure the output voltage is always correct.
it hard to say for sure as the as the chip is missing. if you can get the part numbers for the chip you can then google it and find the circuit diagram/manual which will tell you what they are for.