Small Efficient Power Supply

[Fraser]

From looking closely at the pictures in this thread, I think the switching controller ESD to drive the GaN transistor is the On-Semi NCP1342. I shall study its datasheet but already note that this controller is quite smart in terms of its protection capabilities. So the serious “melt-downs” of the aN transistor and PCB traces puzzles me somewhat. If the current sense resistor is indeed the wrong value that is a schoolboy error surely ?

https://www.mouser.co.uk/datasheet/2/308/NCP1342_D-1509449.pdf

From the datasheet….

• Overload/Short−Circuit Protection: The NCP1342 implements overload protection by limiting the maximum time duration for operation during overload conditions. The overload timer operates whenever the maximum peak current is reached. In addition to this, special circuitry is included to prevent operation in CCM during extreme overloads, such as an output short−circuit.

I believe the switching controller is the NCP1342AMDCD version that is fully detailed in the datasheet.

[Fraser]

A useful video detailing how to calculate the correct primary circuit current sense resistor in a SMPSU

https://youtu.be/wEueXBIgQrE

The NCP1342 has a current sense input threshold of 0.8V

Fraser

[Fraser]

The P200 power supply arrived today 

Having given it a good test with 100W load for over 30 minutes, I have failed to kill it  It looks like I got a good one but time will tell.

Other tests have confirmed that the P200 output supply rail is a little more noisy than I am used to with lab power supplies, but for my needs it is perfect. This unit is Sooo small 

Fraser

[radiolistener]

This unit is Sooo small

and so dangerous...

There is a sense to use electrician rubber gloves and protective glasses with such PSU and check fuses for mains before use. Also keep fire extinguisher near this PSU...   

[Hundleton1]

Well mine blew tonight as well rather unexpectedly on power up with a load.  Anyone have a clue what’s going on here with these.  Thinking of rebuilding but need to check everything else first.

[ono]

I have recently returned my P200 that I initially bought beginning of the last year. P200 size and nice UI were major selling points for me. Also for some experiments I am usually to lazy and also a bit afraid to use more expensive Siglent SPD3303X-E. Almost from the very beginning I was receiving "Input spike!" errors occasionally. I thought it has something to do with regulation of my mains. But then when I made really nice silicon shielded coords for my Pinecils I learned that it cannot power this switching portable soldering iron, because its AC-DC simply does not like the switching and it is AC-DC causing "spikes" that then 2nd DC regulation module complains about. I managed to reproduce this "spike" with 20V and 5R power resistors, that otherwise should work perfectly fine since 4A 80W is below max of this unit.

So I realized this power-supply cannot do anything, but simple battery charging tasks. Also the minimum CC setting of 500mA is absolutely too high to do anything more sensible, such as checking the circuits slowly raising current limit. So in the end it is far from something I'd recommend. Also my ToolkitRC never responded to my ticket regarding "Input spike!". Since I bought it from really good seller in Switzerland, I was able to return it with full money refund with minimal questions asked.

Reading and watching some other reviews I now use Gophert PPS-3205 32V 5A switching power supply as my 2nd bench unit. It is a little bigger than P200, but still very small / portable. It is completely passively cooled, has reasonable ~40mVpp noise on load (as for a switching unit). And ~$60 with shipping price is ok. It works well, although obviously the it nowhere near with 1-2mVpp of my Siglent linear PS. It also clicks a bit when used with Pinecil. I suspect loose coils may be the culprit. So I will keep using USB-C plugged to wall adapter for soldering.