Solution Finder

Line regulation

Posted by: karim19 on Tue, 06/22/2021


I am using the INN3168C-H101-TL for a 35W Power supply, 100Vac - 265Vac

My line regulation is about -1.4% i would like to achieve -1%. The output voltage drops when i reach the low line, is there any way to improve the result?

I have increased the input bulk capacitor, no major change.

Best regards,





Submitted by PI-Spark on Tue, 06/22/2021

Hi karim19,

Thank you for using Power Integrations products.

Can you share the output specifications (VOUT and IOUT) of your power supply?



Submitted by PI-Spark on Wed, 06/23/2021

Hi karim19,

Line regulation of -1.4% is typically already considered a good performance.

But if your application requires a tighter regulation (-1.0%), based on your finding that minimum VAC is the worst case voltage drop, then you might need to adjust your transformer primary inductance.

It is possible that the slight voltage drop you see at minimum VAC is because your power supply operates deeper in CCM as input voltage is reduced.

If the line regulation plot (VOUT vs Input VAC) is relatively flat at high line and suddenly drops at low-line, you can try to reduce Lprimary so that the power supply will be slightly less CCM than the previous design.

PI Expert Online tool helps with your InnoSwitch3 transformer design.

You may use it to ensure the adjustments you make will still result in a valid design (flux density not exceeding saturation, etc)