Which BOM to use for SMPS for BlueNRG-LP: the one from Reference Manual (RM0479 Rev1) or from STEVAL-IDB011V2 - Rev 1 ?

[GBedn.1]

Hi everyone,

I'm confused in regars of BOM for SMPS for BlueNRG-LP. In the Reference Manual we can see the following recommandation:

and in the document for the evaluation board there is another solution:

 

Would it be possible to get an answer if both are correct and which of them is better to use and why?

Regards,

Grzegorz

[Laurent LOUAZON]

Hello Grzegorz,

Both are correct but I do understand this might be confusing.

I hope attached picture will clarify your concern.

Figure 10 of RM0479 is showing both possibilities when using SMPS or not.

When SMPS is used, we must set a 10uH (preferred) between VLXSD and VFBSD.

A 1.5uH or 2.2uH can either be used but will give lower efficiency.

Then our reference schematics is adding a 22nH is series (see explanation in picture attached).

This 22nH is optional and can help in sensitivity performances.

The component D1 is used either with a 10uH in position 1-2 is SMPS is used or with a 0Ohm in 1-3 position is SMPS is not used.

 

Hope that clarifies.

In any case, please try to follow as much as possible the STEVAL-IDB011V2 reference design.

Regards

Laurent

[GBedn.1]

Hello Laurent,

Thank you for the answer - very appreciate it. Now I see the cause which made me confused - there is a lack of "H" in the comment to D1 on schematic :) (it is "10u" instead "10uH") however I sould more carefully check the BOM document for IDB011V2 and then I would notice the "H" :)

I designed my board basing on IDB011V1 and works fine so far.