Hello, I can't decide wether I should connect the GND and VDD pins of my analog switch ADG774 (https://www.analog.com/media/en/technical-documentation/data-sheets/ADG774.pdf) to my digital GND/VDD or analog GND/VDD... The chip is part digital part analog...

Thanks !

 

That's a good question.
The switching currents go to the GND/VDD pins so that would suggest connecting to the digital power and ground, but there can be a small value of capacitive coupling between the GNS/VDD, which could cause some coupling of any digital noise to the analog channel.

How often will the switches be commanded to switch?

 

Every 5ms, ideally every 500us...

I am using 3 capacitance (22uF, 0.1uF and 0.01uF) between VDD and GND, a ferrite bead between GND and GNDA and another ferrite between VDD and VDDA

At this point no noisy digital signal (no SPI, I2C, or other serial), just the uC's clock

PS: My understanding is that the ADG774 has been out there for a while. Any recent/better alternative ?

Thanks !

 

My understanding is that the ADG774 has been out there for a while. Any recent/better alternative ?

Not aware of any.