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ACST1635 AC Switch reference design help

DTuls.1
Associate

Hello experts,

I've been trying to build a small home automation project using ESP32, PubSub client and an MQTT broker on Android. Rest all is fine, but I was trying NOT to use a relay for controlling the appliances. While considering Solid State Relays, I came across ACST1635 from ST Microelectronics. Looks to be a great component since it can handle upto 16A AC load and can be directly controlled using a uC. All that in a small TO220 package.

My trouble is that, I'm unable to understand the design correctly from the datasheet (please excuse my hobbyist electronics skills). Of what I could see, the "COM" terminal is common to the Vdd of the uC board, and also to the Line. But I'm not 100% sure if that is how the setup is. And if that is the setup, wouldn't it be risky to have the Line neutral connected directly to the uC board GND? Is there a better way to isolate both Vdd and Line Neutral? I wonder if there is some sort of short circuit or leakage on the AC side, it might enter the uC board and blow it up.

I looked at the Evaluation Board here but that also did not enlighten me much.

Would someone be able to help me with better understanding how the design is, whether my schematic is correct, and what best to do to ensure safety?

Attached is my reference schematic.

0693W000006HmbrQAC.jpgThankyou so much in advance for your help.

Regards,

Deepak

2 REPLIES 2
DTuls.1
Associate

Hi,

Anyone out there who could possibly offer some kind help?

Regards,

Deepak

Peter BENSCH
ST Employee

Hi, @DTuls.1​ 

You need to drive the TRIAC using a phototriac, which is described e.g. in AN5114.

Regards

/Peter

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