5V PDM sensor, convert to analog, capacitor help

Thread Starter

Vincent Deniros

Joined Apr 2, 2019
7
Hi

I need a little help with a temp/rh sensor that I bought for a Raspberry Pi with a Widgetlords Pi-SPi-8AI (extension board with analog inputs)

The sensor is a T9602-5-A
In the datasheet it looks like this:

t9602.PNG

Then, it also says that users can refer to Application Guide AAS-916-127, to find the processes to convert the Pulse Density Modulated (PDM) outputs to analogue outputs.
The whole guide is about 40 pages, but I think that its something like this that I need:

diagram.PNG

pdm.PNG

My analog 0-5 VDC (0-6.6) input board supports 12 bit resolution.
I tried to connect the sensor as is, but I was getting values like all over the place... (but a steady 2.06V on the input with a cheap multi meter)
So I guess is that I need a low pass filter to even the signal out.

So my questions is:
Can I just buy a couple of 1600nf capacitors and 10k resistors and the signal would be fine?
1600nf/1,6uf isnt the most popular capacitor on the market. Can I for example use 2.2uf?

Thanks in advance :)
 

OBW0549

Joined Mar 2, 2015
3,551
I'd say just about any kind of capacitor, provided its specifications are appropriate for your operating environment. If aluminum, I'd use something rated for 25 or 35 volts, or even more, to keep leakage current down. If ceramic, be aware that capacitors with that much capacitance will usually use dielectrics that are very temperature sensitive and could therefore affect performance at temperature extremes.
 
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