How to use a Zener diode to protect ADC/MCU analog inputs

Maker, DIY
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Hi,

I am using MMSZ5226CT1G to clamp the sensed analog input voltage to a uC. I had used a 1.2k series resistance between the zener diode and the sinusoidal input. The zener diode voltage gets clamped at 2 V instead of 3.3V. I dont understand why. If anyone could give some insight, it would be really great.

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Hello neetusha26,
Welcome to the DigiKey TechForum.
Hopefully the Maker.io_Staff can shed some light on this situation, or one of the Engineers that monitor the TechForum.