Author Topic: KiCAD: Replace a component with a compatible in library, schema, netlist, PCB  (Read 4310 times)

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Offline jancumps

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I created a schema using an IDT IDTQS3VH16245 ic.
In the final design, I want to use the pin-compatible TI SN74CBT16245DGGR, because the IDT chip doesn't work in my context.

What is the right way in KiCAD to replace the IDT chip with the TI one, so that schema, netlist and PCB are correct?
I created the IC and footprint in a KiCad custom library.

I tried to copy the library element and replace the ones in schema, netlist and PCB without loosing connections and traces, but seem to be taking the wrong approach.
 

Offline Bassman59

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I created a schema using an IDT IDTQS3VH16245 ic.
In the final design, I want to use the pin-compatible TI SN74CBT16245DGGR, because the IDT chip doesn't work in my context.

What is the right way in KiCAD to replace the IDT chip with the TI one, so that schema, netlist and PCB are correct?
I created the IC and footprint in a KiCad custom library.

I tried to copy the library element and replace the ones in schema, netlist and PCB without loosing (sic) connections and traces, but seem to be taking the wrong approach.

What is it about the IDT part that "doesn't work in your context?" They seem to be the same device, in the same package.

So to that end, the simplest way to make things sync up is the change, in the schematic, the name of the part in the symbol's value field. There's no need to touch the PCB or regenerate a netlist. Then you can regenerate your BOM from the schematic and it will have the new part number for these parts.


 

Offline jancumps

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I'll try your suggestion.


Quote
What is it about the IDT part that "doesn't work in your context?" They seem to be the same device, in the same package.
Weird, isn't it? GadgetFactory had to spin a new version of their buffer because of this (documented on their site, and also experienced in real life by myself :) :
These ICs are bus switches, they can switch 8 signals at the same time, very fast. As a side effect, you can use them as voltage droppers to turn 5V signals into 3.3V signals, just by applying a particular power supply value to the IC.
But that works for the TI, not for the IDT version.
Documented on Gadget Factory forum, and confirmed by my experience.

 

Offline Bassman59

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I'll try your suggestion.


Quote
What is it about the IDT part that "doesn't work in your context?" They seem to be the same device, in the same package.
Weird, isn't it? GadgetFactory had to spin a new version of their buffer because of this (documented on their site, and also experienced in real life by myself :) :
These ICs are bus switches, they can switch 8 signals at the same time, very fast. As a side effect, you can use them as voltage droppers to turn 5V signals into 3.3V signals, just by applying a particular power supply value to the IC.
But that works for the TI, not for the IDT version.
Documented on Gadget Factory forum, and confirmed by my experience.

Huh, interesting. I haven't used a FET bus switch in awhile.

So what I'd do is to create a new schematic symbol for the part you need to use, then replace all instances of the old symbol with the new one. Make sure the reference designators aren't changed.

There's still no reason to regenerate the netlist or modify the artwork (assuming that nothing actually changes). Then spit out the new BOM from the schematic.
 


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