LM5166: Use in transient 10A application

Hello, 

Thanks for reaching out. The LM5166 is a synch buck converter, therefore I would guess you have a typo in your part number also because I see a boost converter in the picture that you posted.  Which boost controller did you consider for this application? I would suggest a synch boost controller in order to support your load requirements (like for example LM5123). Let me know if you need further help. 

Kind regards, 
EM 

Hi EM

Sorry if my post above cause confuse...

Let me conclude the question as below:

1. The customer is looking for boost converters(not controllers) that supports such application, do we have any solution for this?

2. The picture I posted was also from the customer, as the LM5166 only supports up to 3A simulation he was trying to see if controller + FET solution can meet his requirement. I noticed that you mentioned LM5123, is there any recommendations regarding the FET & thoughts on system considering the gate charge?

Regards

David

Hello, 

Thanks for your feedback. Is your customer then only considering a converter with integrated switch? The load transient spec sounds challenging. Anyway, the LM5166 is a buck converter and not a boost, therefore I would guess you meant LM5156 which is an asynchronous boost converter. In general, in this case I would propose a synch design like with LM5123 and to have an idea you can try to use the Excel Quick start calculator https://www.ti.com/lit/zip/slvrbj1 

Kind regards,
EM

Hi

For LM5123,

If to parallel the FET to lower the temperature, is there anything the customer should be aware of?

Regards

David

Hello, 

I would say that there is nothing really critical other than the usual parameter to consider when choosing a MOSFET (Ids, Vds, Rdson, gate charge, Miller Plateau). Let me know if you need further help. 

Kind regards,
EM 

Hi EM

Thanks for the reply.

Is there any recommendation regarding the open drain controller?

I notice that the LM5123 you mentioned is push-pull type and I think the customer mentioned that he wants open drain solution to cut the size.

Regards

David

Hi, 

Thanks for your feedback. I think we may need to clarify few points: the LM5123 is a synchronous boost controller, meaning that there is no rectifying diode but two FETs instead, which is leading to better efficiency at higher currents and there is no need of an additional push-pull stage to drive the FETs. The LM5156 is an asynchronous boost controller, meaning that there is one FET and one diode, the LM5157 is an asynchronous boost converter where the FET is integrated and only one diode is required. The load transient specs you mentioned sound a bit challenging, do you know what is the max drop on the Vout that the customer could accept during this transient? 

Kind regards,
EM 

Hi EM

Sorry for not following this case.

The customer can accept a less than -4V drop (44V to 48V) in the load transient application I mentioned above, could you confirm if this is achievable with LM5156?

Much appreciate the help!

Regards

David

Hello David, 

Thanks for the feedback. Is the customer currently in possess of an EVM? The best option would be to try it out, but I would still suggest a synchronous approach due to the high current during load transient like the LM5123 as mentioned above.  

Kind regards,
EM