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wagiminator / ATmega-Soldering-Station

T12 Quick Heating Soldering Station
https://oshwlab.com/wagiminator/z-solderingstation-smd-v2
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charge pump question #14

Closed SmallpTsai closed 3 years ago

SmallpTsai commented 3 years ago

Hello,

I am studying your "charge pump" design, please correct me if my understandings are wrong. Thanks a lot!

(based on board version v2.7) image

Left: D9 on -> Q1 on, current go through Q1, so Q2 Vgs is 0, Q2 off. C7 is charged to full (~24v if ignore D1 voltage drop)

Right: D9 off -> Q1 off, C7 start to discharge, Q2 Vgs become 24V, Q2 on. (Vsource = ~23v, Vgate = ~47v)

part requirement: Q1: Vce need to handle > 47v, therefore choose FMMT619 C7: require > 24V voltage D1: require > 24V reverse voltage (in discharge scenario) D4: 18V zener is to protect Q2 gate, IRLR7843 max Vgs = 20V

Thanks.

wagiminator commented 3 years ago

Precisely! The drawing is great, can I use it in the description? Maybe that will help others too.

SmallpTsai commented 3 years ago

sure, please feel free to use it. thanks very much for answering and this interesting project !!

Now that everything is clear, I will try to make my own clone soon :)

wagiminator commented 3 years ago

Many Thanks! I wish you every success with your version and look forward to hearing from the result.