Problem with charge pump voltage

[OlivierD]

Hello,

I am currently using the TMC603 to evaluate the use of brushless motors in an industrial application. I created my own board for this application, but I am currently encountering a severe issue with the charge pump circuit. I used the circuit example in the datasheet. It seems I can't attach it to this post from my computer but I will gladly send you screenshots and oscilloscope measurements by email. The issue is that if I connect the double diode (I used a BAV99) a shortcircuit happens. I tried to replace it with two normal diodes, but whenever I connect the upper one (the one connected to VCP) nothing works anymore.If I don't connect this diode then everything else works but the TMC remains in error mode because the charge pump voltage is not generated.

For information, I am using a 24V DC supply and I didn't use the optional filter connected to VCP.

Best regards,

Olivier

[TRINAMIC_BD]

Hello, you could try adding a second power supply for supplying the charge pump voltage. Probably not the diode is the problem, but a different component or short circuit in the system. I guess you will find it getting hot, once you supply the voltage with an additional supply

[OlivierD]

Hello,

I thought of that and I tried it just now. The circuit works with an external power supply for the charge pump (and without the diode). However, I still don't get why the circuit doesn't work. I thought of something, but I'm still not sure. Does the driver disable the outputs when the error state is activated? Or do we absolutely have to disable the Enable pin? It might have something to do with the Reset parameters of my MCU.

Regards,

Olivier

[TRINAMIC_BD]

Hello,
for some MOSFET configurations this might be the issue: The error output should be coupled to the enable input. One other issue - in laboratory environments circuits are often powered on by plugging the connector to the lab supply. This leads to a very high dU/dt and can even destroy some components, as it also induces overvoltages and overcurrents. It is better to first plug the connector, then switch on the power supply. Did you check the charge pump input current? It should only be a few mA.
If the charge pump is still not willing to work, please first check the switching events with a scope.
I hope this helps.