# TIDA-01063: tidcc93

Part Number: TIDA-01063

Hi,

Does the 'trace cross section area' in line 29 come out in a wrong way? Given dw = 8 mils (line 15), dh = 35um (line 27), the 'trace cross sectional area' cannot be 5.65e-8 m^2. In fact, using Ar= dw*dw it should be 7.1e-9m^2.

Another question is on the definition of 'Turn'. According to 360/4.08 (line 22), the max turn should be 88 rather than 176. Even considering both sides of PCB, the number of traces is doubled to be 176. However, the turn number of coil still should be 88 since one top trace and one bottom together trace form one turn.

Hope to hear from you soon.

Thanks,

Mingyu Xue

• Hello,

We are looking into the calculations you are discussing.  We will get back to you soon.  Thanks for your patience!

Regards,

David

• Hi David,

The second question on No. of turn is clear for me since I read the layout.

Thanks,

Mingyu

• Hi Mingyu,

The conversion factor to go from mils to m for the dw (line 15) is incorrect for the Ar calculation on line 29.  Turns out, Ar is being multiplied by 8 twice which is why the result is 8x larger.  Your calculation for Ar is correct.

As you have pointed out in your last reply, the calculation for # of turns in the spreadsheet is assuming a layout similar to what was used in the reference design.  The number of turns calculated in the spreadsheet is correct.

Regards,

David