TO with T shaped Tab

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I hope this is the right place to ask this... feel free to move it if it is not.

What should I do with a TO surface mount part that has a T shaped tab.

This is the example I am looking at: http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/PD070096.PDF

Here the top of the tab is full width but the majority of it is not.

The Calculator appears to assume a uniform width, but when the tab is not a rectangle, what width is best to use to base the footprint on?

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DaveCowl Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 18 Oct 2012 Location: Santa Clara, CA Status: Offline Points: 161	Post Options Post Reply Quote DaveCowl Report Post Thanks(0) Quote Reply Topic: TO with T shaped Tab Posted: 30 Oct 2012 at 6:05pm
	I hope this is the right place to ask this... feel free to move it if it is not. What should I do with a TO surface mount part that has a T shaped tab. This is the example I am looking at: http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/PD070096.PDF Here the top of the tab is full width but the majority of it is not. The Calculator appears to assume a uniform width, but when the tab is not a rectangle, what width is best to use to base the footprint on?



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 30 Oct 2012 at 6:16pm
	You use the mfr. recommended pattern for your pad shape. National Semi is calling it a "Lead Position Overlay". You may have to tinker with the thermal tab size to auto-generate a close match to the recommended thermal pad pattern size.