Buck Regulator (5V, how to select, automotive application)

[Rajinder1268]

Hi all,
I am in the process of selecting a buck DC DC converter for an automotive application, running off a 12V car battery.
The output will be fixed at 5v @ 1.5A (although 1A) would be sufficient too. I am looking at an automotive criteria i.e. input can go up to 36V (to handle cranking and spikes)
Ideally I need low quiescent current in uA (ideally). I am not sure if I should select a synchronous, asynchronous, simple switcher type.
The current for the application would be around 600mA max. Ideally a small package size and minimum external components.

Can anyone assist?

 

[KlausST]

Can anyone assist?

I always use the online selection guides provided by manufacturer. There you can input all your requirements.

Klaus

 

[dick_freebird]

Not to spoil your fun, but why not buy one of the 6000+ 12V-to-USBC products that turn up on eBay? Under $5 free shipping and probably far cheaper if you live where they're built.

Throw away the case and what's left is more than you ask for. Maybe inspection yields clues.

 

[Rajinder1268]

I have tried to use the online selector using the filters. I get confused when making the final decision as some parts are new, some have additional features that I do not require etc.
I will post a few examples up later. The only issue I have with the 12V to USBC devices are they would have buck regulators that you could not source. Also not sure if they would be adequate for automotive applications.

 

[cupoftea]

Heres one

https://www.diodes.com/assets/Datasheets/AP62200_AP62201_AP62200T.pdf

...you can just add the 36v protection

..or heres one that does to 40vin

https://www.onsemi.com/pdf/datasheet/ncp1546-d.pdf

 

[KlausST]

Hi,

I opened www.analog.com --> parts --> Power Management --> Switching Regulators --> Step-Down (Buck) Regulators
typed in the application parameters.
Then got a table of suitabe devices.

Then I pressed [Choose Parameters] and checked the [automotive] box.
Now you see the [automotive] column, where you can filter automotive devices only.

The list shows at least 10 different devices.

It´s not difficult. Just a coule of mouse press and keyboard inputs. 10 seconds of time.

Klaus

 

[cupoftea]

Thanks, i'm often on the search for cheap Buck SMPS controllers.......say vin to 40v, vout 30v downwards, Iout = 1 or 2A.....its a pain to find cheap offerings for this ......i think its because the hi side fet and current sense need level shifting...theres nothing cheap on offer anywhere.

To be honest you'd be better getting a cheap current mode controller and just doing a SEPIC converter......

I just tried the "search" on digikey for the above spec..........when you try and choose "Buck" or "step down"...you cannot do this simply......there are multiple lines you have to peruse........and on other sites like farnell.....the search engine blue circles on you for quite some time....even digikey it does at times.

When you elect to do a SEPIC with a cheap current mode controller.....you then end up with the ucc28c4x ......and its variants...which all need you to add a shutdown comparator because they cant do skip cycle or burst mode when no loaded.........so yes, the above sepc is a bit of a PITA when youre trying to do it on the cheap.

If youve got pots of money then yes, just go to analog.com and part yourself from your dosh.

...When ive next got a few hours spare to sit in front of a "blue-circling" IC search engine i'll report back here when i find a cheap current mode control IC that can do skip-cycle in no-load, and doesnt only have a feedback port for an opto feedback......sniffling rant over.......hopefully back soon...