ACS, ACST negative voltage schematics ?

[FloSolio]

I found the ACS108-6SA that seems to fit my needs.

1) I will control the gate with my stm32G0B1 uC.

I really don't understand why I have to connect the 24VAC Neutral to the +3.3VCC of the MCU ! It sounds like dangerous no?

i can understand that the current for the gate need to loop somewhere but why to connect the +3.3v to the neutral ?

This device seems to fit my needs and seems to have been designed for this purpose, but the schematics looks really strange at the moment to me.

2) Concerning my need to switch on / off big pump grundfos sba3-45a that is 230vac. this pump looks to have a big capacitor Should i use triac like T410 ACST1235-7GTR for example or ACST1635-8FP ?

I have also pure inductive 88W air bubble to connect on it that pollute a lot the 230vac line when switch off.

[Peter BENSCH]

1. This is the usual procedure when controlling via an MCU. Details can be found in AN2986.

2. If I remember the specifications of your pump correctly, it has starting currents of up to 12A, so a T410 will be too weak. The ACST1235-7GTR should just about suffice, but with the ACST1635-8FP you will have more reserve. Due to the large 12µF capacitor and also with inductive loads, you must provide a snubber to avoid possible dv/dt problems.

Does that answer your questions?

Regards
/Peter