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Request for PF and THD improvement circuits for LNK6448 products

Posted by: minkh1 on Thu, 07/15/2021

Good morning
I tried making a USB Charger Power Supply using LNK6448 among LNK64x4-64x8 LinkSwitch-3 series.
It works just fine by making it the same as the Applications Example.
But this product has poor power factor and THD (Harmonic A), is there any way to secure it?
If yes, please introduce yourself.


Submitted by PI-Chloe on Sun, 07/18/2021

Hi minkh1 

In order to be compliant to power factor and the, a power correction circuit must be added. This is another SMPS topology usually a boost converter to boost the rectified AC to 400V. 

LNK3 output power is up to 10W. Adding a PFC circuit is not practical. 

Additional PFC circuit will add components counts, larger PSU dimension, increase manufacturing time, and cost. 

In a USB charger Power supply it is acceptable to have a poor power factor and THD. 

Usually above 65 W or 70W power supply a power correction is required.