DYP-ME003 on a coin cell / 2xaa battery

[LastSamurai]

Hi, I found several threads for similar pir sensors but none of them helped me solve my problem.
I am designing a small mysensors board that support different kinds of sensors. I plan to run it of of a coin cell or if thats not working 2 aa batteries.

One of the sensors I want to use is a DYP-ME003 PIR sensor. It has a onboard voltage regulator but there is a small pad (H) that can be used to deliver 3.3V volt (and the output is 3V anyways). I connected a stable wall powered 3 V source and it worked without problem.
Now I need to get it to work with my batteries/coin cell though. As a single coin cell falls under 3V I tried to use a boost converter. That only gives strange random results though. Removing the onboard voltage converter of the PIR and adding a pulldown resistor to the data output as well as a LC filter like this one did not help either.
Any ideas how to fix that? Thanks a lot for your help!

[scalz]

Hi.

I have not so much experience with pir modules. I use an homemade pir, which works well and I am doing my own software for programmable features like nb of pulses for validating a trigger, blindtime etc..And it's a coincell board without any regulator, so..

But in your case, what I would do..(and it's easier with a scope !), is:

• LC filter, and you could add one capa before inductor too
• in some case, and maybe in this case, it's better to place the LC filter near the chip you want to clean (like radio or your pir module for instance). This is when you have enough room. But when you have not enough room, so it's easier to place the LC filter just after the booster, for all the board.
• use a good PSRR etc LDO for you PIR module. I think if you power directly the PIR module from the booster, without LDO that could be difficult..because of the mV PIR variation of analog part. Having a good ldo could help to smooth a bit too..
• adding multiple, different small capa value near your pir module, for smoothing some frequencies...And you could add a 100u to absorb some voltage fluctuations too.

So, you have to choose values for capa vs frequencies you want to filter. And another thing too, you need to choose the right inductor, they are not all equal..(datasheets curves and frequencies you want to filter ...)

I hope this helps a bit