LP5521 - About the mounting to "double-side board"

Hello Kanemaru,

Which package option your customer is using? The DSBGA or the WQFN?

With WQFN you can mount on "double-side board" (two-layer board).

With the DSBGA you would need the microvias and they have restrictions in the relationship with the via size and via length. Of course this depends on board manufacturer, but small vias usually cannot go through whole board.

Unfortunately we do not have example PCB layout for "double-side" board.

Thank you,

Sami

Hi, Sami

Thank you for the information.

Package is DSBGA .

I understand it as the following but is this correct?

If vias are small, radiation performance are bad.

Therefore, the board recommends " Four layer board " than " double-side board ".

Or, does it mean that small vias cannot penetrate “double-side board” physically?

> but small vias usually cannot go through whole board.

Regards,

Kanemaru

Hi Kanemaru,

I checked this again I need to somewhat take back my answer. I learned that It is also doable with DSBGA device. You would need to carefully place the microvias that go through the board, so that they would not break any PCB rules. This is also dependent on the board manufacturer, how they recommend this. Some small manufacturers might not be able to do this.

Also it depends on the application. For example if you tie address selection pins to GND (like in the typical application circuit) you would have less signal going to the other side. Also the use of the GPO and CLK_32K pins have an affect on this.

Regards,

Sami