Clicking
on one of the family color bars will take you to a page with
details on individual sizes within that family.
Calculating
the Sizing Factor
|
1
|
Add output
WDC, output rectifier losses, and output inductor losses. |
|
2
|
Multiply
the result from Step 1 by one of these topology factors: |
| |
| • |
1.00
for push-pull center-tapped primary, full-wave center-tapped
secondary |
| • |
0.86
for bridge input primary, full-wave center-tapped secondary
(use 0.72 for full-wave bridge output) |
| • |
0.93
for current-fed bridge input primary, full-wave center-tapped
secondary (use 0.77 for full-wave bridge output) |
| • |
2.05
for forward converter |
|
2.24
for fly back converter |
|
|
3
|
Multiply
the result from Step 2 by the temperature rise factor (assumes
50°C ambient): |
| |
| • |
1.00 for 40°C rise |
| • |
0.73 for 60°C rise |
|
| 4 |
IEC spacing
requirements will increase the sizing factor. Note that certain
families are more appropriate for IEC spacing (they require
a smaller increase in the sizing factor.) The following table
gives the range of factors for two recommended families, using
standard spacing techniques: |
| |
IEC
Spacing
| Family |
2mm |
4mm |
6mm |
| EFD |
1.11 - 1.50 |
1.25-* |
1.43-* |
| ETD |
1.06 - 1.12 |
1.11 - 1.26 |
1.17 - 1.45 |
|
| |
Note: The
smallest factor is for the largest size in the family; and
the largest factor is for the smallest size. The asterisk *
indicates that standard spacing techniques cannot be used on
the smallest sizes in the EFD family.
Special
techniques can be used to reduce the factor on all families
to approximately 1.10. Contact Precision
engineering for more information.
|
| 5 |
Multiply
the result from Step 3 by the standard or special spacing factor
from Step 4. |
| 6 |
Your final
result is the “Sizing Factor” for use in the Product
Family Sizing Chart (click
here). |
|
|
