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TOP258Y not switching

Posted by: mehmetel on

Hello;
We are designing a flyback converter using top258y with the gudance of an example design :

http://ac-dc.power.com/design-support/reference-designs/design-examples…

We designed the primary side similarly, just the transformer and and secondary side designed for 24 V output. We see the input voltage on drain pin, however control pin is always stays at 1.78 volts, so top258y is not switching. In datasheet, control pin should be between 4.8V-5.8V interval. We set up the test circuit,but again we see 1.78 V in control pin again.Do you think our top258y are fake?

Comments

Submitted by PI-Terry on 01/27/2015

Hi,

Would you please let me know what is the detail modification (transformer structure both secondary side and primary side, components...etc.) you made from the DI197 to your design with 24V output?

Submitted by mehmetel on 02/10/2015

In reply to by PI-Terry

Hi; we have solved the problem, the switch is fake.We replaced it and see working.Thanks for help.

Submitted by Anjana Salgaonkar on 03/10/2015

hi .. i have designed 30W smps with top switch 258Yn of input range 40 to 100VDC. i want to know about current limit and power limit calculations in detailed.... can u explain me with detailed example?...... please help....

Submitted by PI-Terry on 03/18/2015

Hi,
Thanks for contacting PI.
The current limit is basically fixed by the device, that you can refer to the data sheet. With certain current limit, depending on the design working under discontinuous mode or continuous mode, the power limit could be very different. I would recommend you to read the data sheet and the application note from us for a starting point. Moreover, PI actually provides very helpful software tool to help the engineer to do the design. Please find the related information as following:
http://ac-dc.power.com/design-support/product-documents/data-sheets/top…
http://ac-dc.power.com/design-support/product-documents/application-not…
http://ac-dc.power.com/design-support/pi-expert/

Hope this is helpful.

Submitted by kpratik on 06/18/2015

At times not all types of cores are suitably available..
When we try to change the core as per availability is there an source or documentation that would clear out all our doubts on chosen cores and proceed with the design ?
Agreed that PI Expert Suite provides the necessary details.. Not only cores even the choice of wire and no. of cores in wire matter which are an subject to availablity ... How does one clear this aspects out ??

 

Please help...

Submitted by PI-Kenobi on 06/19/2015

I think you are trying to use a custom core and want to add your core parameters into PIExpert. If this is true, then you can do the following:

1. Start PIExpert, but do not create/open any designs

2.  Go to Tools->Component Library...

3. You must now see the 'Transformers' tab. Click 'Add' and enter your custom core details.

4. This custom core will now be available for design in PIExpert

 

As for wire, once your design is complete, you can easily go to Active Design->Edit Design->Winding Construction->Primary and Bias...

Here you can change the wire size per requirements,