DF06M View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'DF06M' PDF : 42 Pages View PDF
AN1262 APPLICATION NOTE
Table 11. Wire Table (RS-214). Copper wire. Heavy insulation.
AWG
Diameter
Copper
[cm]
Diameter
Insulated
[cm]
22
0.064
0.071
23
0.057
0.064
24
0.051
0.057
25
0.045
0.051
26
0.040
0.046
27
0.036
0.041
28
0.032
0.037
29
0.029
0.033
30
0.025
0.030
31
0.023
0.027
32
0.020
0.024
33
0.018
0.022
Area
Copper
[cm2]
0.003255
0.002582
0.002047
0.001624
0.001287
0.001021
0.000810
0.000642
0.000509
0.000404
0.000320
0.000254
Area
Insulated
[cm2]
0.004013
0.003221
0.002586
0.002078
0.001671
0.001344
0.001083
0.000872
0.000704
0.000568
0.000459
0.000371
Finally the total winding area must be checked to make sure they fit the bobbin window Aw:
Api · Nwp · Np + Asi · Nws · Ns ≤ Ku · Aw
(14)
where Api and Asi are the individual wire cross-section, primary and secondary respectively, including isola-
tion. If the above inequality is not verified there are the following options:
a) if Np is quite larger than Npmin, try decreasing Np and go back to step 3;
b) choose a smaller wire, recalculate Nwp and Nws and recheck window fitting;
c) use fewer wires in a strand accepting a likely larger temperature rise;
d) use the next size core and restart from step 2.
Finally, the auxiliary winding will be defined. It has not been considered before because it handles a very low
power, thus it will be made with a single thin wire (e.g. AWG32 or AWG33) which gives a negligible contribu-
tion to winding build and losses. Just the turns number needs to be defined:
Naux = Ns ⋅ V-V----Co---uC---t--+-+----0-V---.-F7--
(15)
where 0.7 V is the typical forward drop on the auxiliary (small signal) diode.
8) Calculate actual power dissipation and hot-spot temperature rise. The actual resistance of the primary and
secondary windings has to be calculated first:
Rp = ρ100 ⋅ N-----w---N--p--p---⋅--⋅-A--L--p--t--C----u- ; Rs = ρ100 ⋅ -N----w--N---s--s---⋅--⋅-A--L--s-t--C----u- ,
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