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Joined: 31/12/2012
Location: New ZealandPosts: 10037
| Posted: 10:37pm 08 May 2019 |
These modules do have a habit of burning out the chip if they are adjusted incorrectly. Page two of the PDF for this boost-converter chip, states that the voltage on the FB pin(3) is 6v absolute maximum. Many of the modules from eBay etc don't use the correct potential-divider arrangement, and if the multi-turn trimmer is set so it favours the supply-rail end of the travel, you will EASILY apply more then 6v to the FB pin, and then the device has an internal breakdown and catastrophic failure of the device then follows.
These modules seem to use the basic circuit on page one of the PDF, but they have replaced R1 - which is a set value in the basic circuit - with a variable resistor - the blue multi-turn trimmer. What this allows to happen, is that the potential applied to pin three, can EASILY be set to more then 6v with respect to ground, and then the chip will fail - usually by way of burning itself into silicon heaven.
I have attached the PDF in case you don't have it.
2019-05-09_083259_MT3608_Step-Up_converter.pdf
The best way to adjust these units, is to NOT apply more then 6v at initial adjustment, that way, there is no way for pin three to rise above 6v. I would use 5v or so. Then you adjust your output voltage. When fed with LESS then 6v, they work just fine. I don't recommend using these modules above 5v with the arrangement of the circuit used on these modules. They certainly CAN run from an input voltage up to 26v, but you have to be sure that the potential on the FB pin is LESS then 6v, and the simple divider used on these modules does NOT prevent that - so the modules self-destruct when you exceed that maximum.
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