Isolated AC/DC Power Supplies Solution

At this power level (168 W), is PFC required?

Yes it's preferred.

If it's not preferred, which solution should I consider?

If you want a solution with PFC, you could consider the following as possible starting points.

PFC option:
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http://www.ti.com/tool/PMP5141

This is rated for 85-265 V ac, output is 24 V @ 10 A, eff is 90% - so it could be modified for the lower 7 A output requirement.


Alternatively, if PFC is not required (depending on the application requirement), there are some options, but none is a perfect fit:

No-PFC option 1:
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http://www.ti.com/tool/PMP9643

This is rated for 90-265 V ac, 24 V @ 2.7 (continuous), up to 5.4 A (surge). If the IC used is changed to UCC28631 or UCC28633, the overload timer is disabled, so the power stage can be operated continuously at 5.4 A, assuming the power components have suitable heatsinking. With some redesign of the transformer and power stage, it can probably be further adapted to get 7 A output, however, the output rectifier diode will be the bottleneck.


No-PFC option 2:
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www.ti.com/.../PMP10912

This is rated for 24 V @ 6 A, however the input is limited to low line only (100-138 V ac), because it uses an internal voltage doubler and 2-switch Flyback for improved efficiency. If you can tolerate low-line only, this could be useful.


No-PFC Option 3:
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www.ti.com/.../PMP10804

This is rated also for low-line only, and is 24 V @ 4 A output. However, it does not use a voltage doubler, so it may be more easy to modify for wide input AC range.


There are many other lower power designs available. You can search all TI-Designs using the parametric search available here:
www.ti.com/.../refdesignsearchresults.tsp

and click on the bar "Search power reference design parameters".

Thanks

Found that PFC option and non-PFC option 1 have a lot of external components. Can you recommend a lesser components in terms of total component cost < USD 10.

You can browse the range of TI reference designs to see if you can find something else that suits you better. You go to this page, then click on the button "Search power reference design parameters", where you can refine by input voltage range, output voltage and current, AC or Dc input, isolated or non-isolated, etc.

www.ti.com/.../refdesignsearchresults.tsp