115Hz 60Hz flyback with Innoswitch

Posted by: treez on 04/18/2026

Hi,
We wish to use your Tinyswitch for our 92-130VAC input flyback. 10W.
Its class I, Cat II.
Its for industrial use in USA.
Please advise what is the primary to secondary clearance distance required?
Also, please advise what HiPot test voltage we will need to use for primary (L+N) to secondary?

Also, please advise what HiPot test voltage we will need to use for primary (L+N) to Earth?
Also, it has an earth connection from the mains input cable.
Please advise what is the clearnce distance required between Line and Earth?

By the way, the secondary ground will be earthed.
This SMPS will be in a metal enclosure.

Please also advise about App Notes you may have for similar 115VAC designs? (ie not wide mains, just 115VAC)

Comments

Hi treez,

Thank you for your continued support to Power Integrations solutions.

For us to further review we would like to ask the output specifications for this design.

Looking forward to your response.

Thanks, Vout = 24V

Hi treez,

Good day. For your application with 92–130 VAC input, Class I, Cat II, PD2, the following requirements apply under IEC 62368 1 standard:

1. Primary to Secondary Clearance: Minimum 2.54 mm
2. HiPot Test Voltage – Primary (L+N) to Secondary: 4 kV DC for 1 minute
3. HiPot Test Voltage – Primary (L+N) to Earth: 2 kV DC for 1 minute
4. Line to Earth Clearance: Minimum 1.27 mm

Additionally, the TinySwitch is a non-isolating device. For the primary and secondary requirements of your power supply design, we recommend referring to the IEC 62368 1 standard or consulting your compliance team or contact for further evaluation.

I hope this helps.

Hi treez,

As this inquiry relates to safety and standards, we recommend consulting your safety and standards team to confirm that the suggested values align with your certification requirements. These values are provided solely to support your process, and we will not accept responsibility for certification failures that may occur if reliance is placed exclusively on these suggested values.

Thanks very much.

The thing is the secondary ground is earthed in the application.

So its hard to understand how Line to earth can be just 1.27mm....but Primary to secondary clearance is 2.54mm?

Also, with a Line to Earth Clearance of 1.27mm, the Hipot test voltage of 2kV for one minute will bring about flashover.

(ie bearing in mind that (L+N) to earth Hipot test voltage is, by your kind words, 2kV for one minute.

Sorry, by the way, i forgot to say that inside the metal enclosure is potted, and as such, does this effect the clearances and HiPot test voltages at all? Also, does the use of potting make it a "Pollution Degree 1" product?

Hi treez,

Thank you for your responses. For any further safety‑related considerations, we strongly suggest that your safety team assess these details directly. We appreciate your understanding.