Selecting a small a 0.5W to 1W DC/DC module

[741]

I'd like to find a series of DC/DC modules that I can "Go To" by default.  At present I'm looking at 5V-->12V Modules.

I have in mind the following

• Nice if the DS includes output filtering suggestions, in case the end application is analog
• One Output
• Withstands continuous short circuit
• SMD or PTH, prefer low profile
• Regulation not too 'loose'. Subjective/comparative with similar modules.

The choice is bewildering. Most datasheets I've looked at omit details of suggested output filters. Also some devices have a pretty wide tolerance of possible switching frequency.

I've just come across a castellated module from Murata (MGN1 Series), and I see no inductors, but I'd be impressed if it was done with switched capacitors.

My current Mouser search is this
https://www.mouser.co.uk/c/power/dc-dc-converters/isolated-dc-dc-converters/?input%20voltage%2C%20nominal=5%20V~~5%20VDC&mounting%20style=PCB%20Mount%7C~SMD%2FSMT~~Through%20Hole&number%20of%20outputs=1%20Output&output%20power=660%20mW~~1.32%20W%7C~1.5%20W&output%20voltage-channel%201=12%20V&instock=y&active=y&sort=pricing&rp=power%2Fdc-dc-converters%2Fisolated-dc-dc-converters%7C~Mounting%20Style%7C~Number%20of%20Outputs%7C~Output%20Power%7C~Input%20Voltage%2C%20Nominal%7C~Output%20Voltage-Channel%201

[ajb]

Are you specifically looking for isolated converters? Most of those have unregulated outputs, so you’d need to add a regulator at the output if you want better load regulation.  Parts with regulation built in are less common and harder to second-source.

The MGN1 series has a transformer made from tracks and vias in its PCB— that’s why it’s so thick compared to a typical PCB, so they can fit additional layers. mikeselectricstuff did a video on them a while ago.

[Benta]

I've been very satisfied with the Traco isolated/regulated converters. Not the cheapest, but they just do the job.

[741]

OK Thanks all - both replies are interesting.

Are "unregulated outputs" basically open-loop?

In cases where I want a clean output, I'd be trying ferrite chips/beads plus LC. Wondering about a CM choke also.
It'd be nice to know if there is a write-up on the general subject of cleaning up DC/DC outputs and/or tests evaluating actual modules.

[floobydust]

They run open-loop so output voltage moves around with Vin and load. I don't know of any regulating based on primary back-EMF (no opto-coupler etc. used) at the low power.

These DC-DC are always noisy and you will find their switching frequency plus harmonics on the output. 300kHz-1MHz switching and then a lot of hash, so powering audio stuff needs extra filtering. I use a common-mode choke and then output pi-filter. The modules will also pollute the primary-side DC power, if that is a concern.
I hate that you have to add capacitors on both input and output, inductors too but this is how it is.

Traco found in russian military gear not sure if the supply chain for them is affected i.e. whale buying.
Mornsun is on the sanction US list and pulled from disti shelves.
Wurth offers a few new modules and app notes but their website is hard navigate for them. I found 176881212.
You will find a common footprint can get used too between companies. SMT versions can be a bit heavy and shear off the PC board if the product gets dropped hard.
Watch the isolation voltage rating if you are safety-isolating, as well as the achievable spacings on the PCB footprint. Some have pins close-spaced, oops.

[741]

I quite like the look of the MGN1 series. It would be nice if I could find specifications for maximum capaciative load though. The DS loosely hints at what is acceptable

Capacitive loading and start up
The typical start up for single output variants, using a 56uF capacitor is 10mS.

Basically, the module is designed to power gate-driver circuits, and I do not know in what way this affects its suitability for general purpose use.


The pin-out diagram is confusing. This is a castellated i.e. SMD package, but it seems the pin-out is shown from below -if the "dot" on the photo is near pin #1 (?).