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I've been looking at the Datasheet of the TPIC6C596 and I'm not sure if the DMOS that is mentioned in the package can be used as a potential free.

I also don't know in general if a DMOS can be used as a potential free contact.

According to this functional Block Diagram the DMOS will just switch the Drain to GND if powered. So I wondered if this counts as a potential difference in the switched circuit.

FromDatasheet

Here's an example of what the circuit with the TPIC6C596 would look like:

schematic

simulate this circuit – Schematic created using CircuitLab

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According to this functional Block Diagram the DMOS will just switch the Drain to GND if powered. So I wondered if this counts as a potential difference in the switched circuit.

What is not drawn in that Block Diagram is that the GND connection is also used for every other block in the circuit. All the latches, AND gates and inverters also use this GND.

There is only one GND pin on the chip.

So no you cannot assume that the DMOS switches are in some way isolated from the rest of the circuit. In your example circuit, the GND of the TPIC6C596 must be connected to the ground of V1 at the left. Without that connection you will get unexpected results.

Also if you would still do this and create a voltage difference between left and right sides the ESD protection diodes will start to conduct if you make a voltage difference of more than 0.6 V.

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  • \$\begingroup\$ So in essence I read that datasheet wrong. Thanks for the answer. \$\endgroup\$
    – HackXIt
    Jun 5, 2019 at 12:38

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