I bought this dc dc boost converter yh11068a



I powered this with adapter 12vdc - 4A
And the output was stable and It worked so great for a few day

a week later i was working with it and i surprised the output voltage it goes up to 600v when i set the resistor to give output 200v.

So now when i set this module resistor to give an output lower then 200v it works great but if i set it up 200 it goes to 600v and even more!!!!


Why?! And since the datasheet say it has an output overvoltage protection and i was working grealty!!!!

Datasheet

https://dalmura.com.au/static/YH11068A.pdf

 

You get what You Pay for ............. Sometimes ......
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Welcome to the world of cheap crap.

https://www.amazon.com/DEVMO-45-390...iewpnt_rgt?filterByStar=critical&pageNumber=1

It used to be that you could trust most manufacturers to provide reasonable quality products, at least for the price being charged. But that ended quite some time ago. It's now becoming increasingly important to spend way too much time researching reviews -- and keeping in mind that those are often highly polluted with fake positives (and some fake negatives, to be fair), in order to try to find something that has any likelihood of actually working.

 

I realise the problem with the adapter ( power supply to this chip)

I was using adapter 12v and maximum 5A, after current measurement i realise this adapter goes over current than it rating ( more than 5A) when connected to this chip

So i added a resistor 50watt 3.9ohm and the chip worked fine ( but fill up the capacitor connect to the chip so slowly)

I also replaced the adapter with 12v 2A one and worked fine again but also slow, i am planning to get 12v- 3A or 12v 4A adapter to test.

The thing i surprise in that problem and do not have an idea why this happened is this 12v - 5A was working fine and fill the capacitor really fast without any overvoltage output from this chip, why it is not working like this anymore?!!

Ps:
I know this chip is cheap but i think this is the only chip i found to give output voltage up to 390v
And even if i found more expensive chip, what will be the difference! It would be the same but most probably has a current limiter or overvoltage output protection ( which i am working on it)

 

The Module that You have, most likely, has a "Flyback" Topology.
This Topology is particularly "Noisy" and difficult to regulate accurately.
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But it works when use lower current about 3A - 4A

 

After You learn how they work, it will be obvious to You why they have so many quirks.
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What size cap are you charging with this converter?

The data sheet says 200mA max output current...and that is at lower output voltages.

Do some math and you might be surprised just how much current a cap draws when charging from a discharged state.

 

What size cap are you charging with this converter?

The data sheet says 200mA max output current...and that is at lower output voltages.

Do some math and you might be surprised just how much current a cap draws when charging from a discharged state.

Cap 450v 1000uf

How ?
Did not understand you