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Posted by: Ravik on

Hi,

I used product selector for below specification

Input 230v AC, 50Hz, Output 5V & 550ma.

I got LNK623PG  with EEL16 core.

The things I observed that transformer is little bit complicated for

production ( due to shildwinding , four parallel string ,small size)

but

If I use TNY284PG I get EF12.6 core and simple two winding ( no shild winding,no parallel winding )

The question is,

1) Can I go with TNY284PG  design?

2) For TNY284PG software suggest AWG 37 & AN-23 says do not use wire thinner than 36 AWG

3) Isp = Ip x (Np/Ns) and Ip equals to maximum ILIMIT but for TinySwitch III & 4 software select minimum ILIMIT,

    its also effect on secondary RMS and ripple current.

4) Why software suggest shild winding for LNK623 and not for TNY284

  does EMI is less in TNY284?

Thanks

Ravik

 

Comments

Submitted by PI-Kenobi on 08/09/2016

1. When you create a new design using the PIExpert tool, you will be prompted for 'Default Design Settings'. See attached image. In case of the LinkSwitch-CV design, the 'Use Shield Windings' option is checked and in case of TinySwitch-4, this option is unchecked, which is the reason you see the cancellation windings in one case and not the other. The choice of one design over the other is based on what your design requirements are. If you do not want the shield windings, feel free to uncheck them.

2. The application note is a general guideline. If you decide to use a wire thinner than AWG37, then you may or may not have issues as outlined by AN23.

3. ILIMITMIN selected by the software is the minimum possible value of the current limit under STD/RED/INC conditions. I am assuming you have used the increased current limit for your design. If this is true, then the software selects the value of the current limit under the worst case tolerance. This can be verified by referring to the datasheet (Tiny 3/4).

 

Hope this helps!

Attachment Size
Default design settings 30.9 KB