FEDEVEL
Platform forum

ha123 , 01-01-2025, 08:32 PM

Hello,
I'm planning to power an ESP32 module with 3.3V using a buck-boost converter. My goal is to reduce noise, especially during transients from Wi-Fi or Bluetooth activity. I don't want to use an LDO because it's too inefficient for my application.

I'm considering using an LC filter to clean up the output of the buck-boost converter, but I'm unsure if this is the best solution. Has anyone tried this? If so, should I just pick the largest low-ESR capacitor and inductor, or are there specific values I should aim for?

Any advice would be greatly appreciated!

QDrives , 01-02-2025, 03:17 AM

What is the reason for "My goal is to reduce noise"?
If you need low noise for analog, just make that section low noise.
Adding a filer makes the system slow to respond to the transients. So you make trade-offs between the dV caused by switching versus the (easily 100x more) dV caused by the transient.
The faster you make the VRM (Voltage Regulator Module), the lower the current transient will be. But in order to get it fast, your ripple voltage from the switching will be higher.

ha123 , 01-02-2025, 03:36 AM

Thanks for the explanation! My main concern is avoiding brownouts for the ESP32 module during transients caused by Wi-Fi or Bluetooth activity. I'm not as worried about noise for analog sections; I just want to ensure the ESP32 stays powered reliably without voltage drops disrupting its operation. Would an LC filter help with that, or should I focus more on improving the VRM's transient response?

QDrives , 01-02-2025, 04:06 AM

An LC filter makes it **worse**!
What is the nominal supply voltage of the ESP and what is the tolerance?

Robert Feranec , 01-02-2025, 11:19 AM

I agree with @QDrives . You may not want to use LC filters in powers especially if higher currents are needed. A good power supply (properly rated based on your maximum current) + decoupling capacitors and their placement should be enough. EPS32 doesn't need so much current. I would recommend to watch this https://youtu.be/HaLMjVkKYMw?si=5nDPnih1_b7BDFdV

Robert Feranec , 01-02-2025, 11:19 AM

and this

Robert Feranec , 01-02-2025, 11:19 AM

https://www.youtube.com/watch?v=ARwBwHZESOY

ha123 , 01-03-2025, 08:46 PM

Thank you for the help. I'll be using a 3.7 volt Lipo

ha123 , 01-03-2025, 08:47 PM

These videos are really helpful thank you. Qdrives is right, It seems that I'd actually want to reduce inductance so that during current load transients I get smaller voltage spikes. So I won't be using an LC filter but just a capacitor

ha123 , 01-03-2025, 08:47 PM

ha123 , 01-03-2025, 08:49 PM

I'll be using a 1.5 to 2.5 Mhz regulator aswell since based off the equation I will get a lower voltage spike.

ha123 , 01-03-2025, 08:50 PM

Based on that I decided to use a TPS6380 buck boost converter since it seems to have a good load transient response

ha123 , 01-03-2025, 08:50 PM

ha123 , 01-03-2025, 08:54 PM

As extra protection, I will put a low ESR 470uf capacitor next to the module.

ha123 , 01-03-2025, 08:56 PM

Do you think I would be missing anything or would this method work?

QDrives , 01-03-2025, 09:04 PM

I assume you simply mean on the input?

ha123 , 01-03-2025, 09:05 PM

Yes