LM25010-Q1: DC/DC BUCK RECOMMENDATION

Hi David,

Thanks for reaching out to see our new devices.

If you would like to have a similar package as the LM25010-Q1, I would recommend the LM5160-Q1 which is a COT device that comes in a HTSSOP package. 

If you are ok with changing the package, please take a look at some of our newest offerings:

For your input conditions, I would recommend checking out  the LMR38010/20-Q1, which supports up to 1A/2A load respectively. These are synchronous converters, and utilize peak current-mode control. 

Since the LM25010-Q1 is a non-sync COT device, a part similar in the profile is the LM5013-Q1 and LM5012-Q1. 

Let me know if you have any other questions.

Cheers,

Richard

Dear Richard,

Firstly many thanks for your comments.

We have made a deeper study of our needs, and we need at least an efficiency of 85%. Our conditions are Vin: 8.8v-36v Vo=5V, Io=0.65A

I checked the references you send me and I have a pair of winners:

Synchronous performance: LM5160-Q1, LMR36015-Q1, LMR38010-Q1

Asynchronous performance: LM5012-Q1, TPS54140

Which would be your recommendation? We are looking for a converter with long life.

It has been a little bit difficult to work with workbench and asynchronous parts. The diode is important for the final efficiency and the displayed values for Vf are for Ifmax. 

Do I have to create a "custom part" to calculate the losses on the diode more "efficiently"?

Thanks for your time.

David

Hi David,

From your previous part, it looks like you were working with an automotive application, so in this case I recommend using only the parts with the -Q1 suffix. In either case, I would more likely recommend things like the LMR36015-Q1 and LMR38010-Q1 since these parts require fewer components than parts like the LM5012-Q1.

Additionally, on the first page of the LMR38010-Q1 DS, you can see that you are able to meet the efficiency requirements at your max input voltage and load conditions. 

With Webench, you will most likely need to create a custom part to calculate the losses on the diode more accurately. I'm sure as you're familiar that there will be deviations between the accuracy of the model and actual results. 

Let me know if you have any other questions. 

Regards,

Richard

Dear Richard,

Yes we were using an AEC-Q100 qualified part, but we are not going to use it on a automotive application. We want to use the buck converter for a home appliance device. Which is the plus that we have using an automotive reference? Is it the working temperature? are the not automotive qualified references have a shorter life cycle? 

I am thinking to test the LMR36015-Q1 or the LMR38010-Q1 but the demoboard for this second converter is built with the LMR38020. is possible to replace "easy and fast" the converter? is the evaluation board ready to use smaller inductors?

In other hand, I was thinking to test the async LM5012Q1 but the evaluation board is for the LM5013 3.5A part and I think that will happen the same that with the LMR38010 evaluation board.

Which would be your recommendation? Which part will have  a "longer" life-cycle?

Best regards,

david

Hello David, 

Richard is currently out of office, he will provide an update as soon as he returns.

Regards,

Oscar Ambriz

Dear Richard,

Thanks for your reply.

We have decided not to use the AEC-Q100 reference in our design. We do not have any specification about it. According to the stocks we will use the commercial or automotive part.

I received my evaluation board and I tested the efficiency with different input voltages and the results were "great".

The inductor used in the LMR36015EVM is tiny (40mm x 40mm  XAL4040-153MEB) compared with the recommended one in the WEBENCH project (10mmx10mm 7447714330).  The inductance value changed, as well. (changed from 10uH to 33uH).

I do not understand the reason of this changes. In my webench project changing the optimization I do not obtain these inductance values. 

I  am trying to configure a new project in WEBENCH with the BOM of the evaluation board but perhaps, you have it.

Could you share it with me? Why Webench is not connected with what we find in the evaluation boards?

Thanks for your time and help.

Best regards,

david

Hello

There are two EVMs.  A 400kHz and a 1000kHz.  They will have different inductors.

You can check the BOM from the EVM user guide.

Webench will optimize differently than what was used on the EVM.

Thanks

Dear Frank,

Yes, I know that there are two models of buck converter according to the switching frecuency as we can see in the chapter 6 of the data sheet (SNVSB49D REV Sep_22), in the LMR360xxxEVM User's Guide Table 1 as well.

In the schematic of the demoboard that we found in the user guide (chapter 3), the reference of the converter is LMR36015ARNXR. It means that the used converter is working at 400kHz.

If I check the BOM the part number used is not clear. It appears LMR36015 and this MPN is generic.

I have taken a photo of the mark of the converter with the microscope and, as you can see in the attached picture the mark is "NH15A" that is similar to the mark of a LMR36015ARNXR (400 kHz).

In my WEBENCH project for  LMR36015ARNXR ‑ 8.8V-36V to 5.00V @ 0.65A the  inductor used is 33uH and the size is 10mm x 10mm.

In the demoboard LMR36015AEVM, the inductor used 10uH and the size is 4mm x 4mm.

You can realize that the size difference is very high ...

Do you have a Webench project of the LMR36015AEVM demoboard  where I can check the results and compare them with the results I obtained in my Webench project?

Best regards,

david

Hello

You can change the inductor in the Webench design and assess the results.

Thanks