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When to Use Multi-Slot Device vs. Hetero Type 2 Device?

Question asked by eric.brown on Jul 29, 2014
Latest reply on May 4, 2015 by eric.brown

Good day folks,

 

I reviewed the info at the Technote MG583318 and found it quite helpful, especially the videos.  I am using the DxDesigner with PADS 9.5 (the ES setup).

 

But, I am still not really sure when to set up a Hetero Type 2 part instead of using the Multi-Slot technique.

 

Let me take a simple example.  Let's say I've got a SN74LVC2G14DCKR (Dual Schmitt Trigger Inverter) and I would like to have two ways to use this device in a schematic.  One way I may want to use it (if, for example, the circuit is simple and I want to keep the gates and Power / GND pins together) is to make a symbol like this (the PKG_TYPE Property is set to TI_DCK for me when I go to layout with PADS):

 

Entire Device.png

 

In this first case the issue of HETERO or Multi-Slot is not a concern.  But, now let's say for the second kind of usage I want to split the gates into two pieces.  And whether I implement the first kind of usage or the second I want the Symbol(s) to reference the same PKG_TYPE going into PADS Layout.

 

Is it better to follow the Hetero Type 2 method, or the Multi-Slot method?  Why would I choose one over the other?

 

In any case, I want the ability to have the PADS 'forwarding' interface assign as many packages (physical parts) as needed and I would like to preserve the ability to swap pins and gates as necesary to make the layout as clean as possible.  Also, I would want to be able to make sure Power and Ground connections are assigned for each part package.  And, of course, I need to be able to overrride those pins with the specific Power Supply I am using (might be 5 VDC in one place on the circuit and 3.3 VDC at another place althoug it is is clear to me that the Designer will need to not mix those).

 

Many thanks for any advice and info!  Best, 
Eric

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