NTC Thermistor noise disturbance

Status
Not open for further replies.

funnyKedougou

New Member
Hello, I am new in this community and I am glad to a membre.
Actually I am bloked since almost 1 mouth on a problem. Look at the circuit below


the NTC thermistor returns wrong values due to disturbance coming from nearby MOSFET. see below

I tried to create a filter by changing the C105 value to 200n or to add a 10k R to create a PI RC filter. But noise reduced but stay high.

Can please give some new ideas ?

Thanks
 
funnyKedougou said:
I tried to create a filter by changing the C105 value to 200n or to add a 10k R to create a PI RC filter. But noise reduced but stay high.
Click to expand...
Is the filter close to the MOSFET input, where it should be?
Have you tried increasing the value of the capacitor?
 
Yes the CTN and RC very close to the Mosfet, the reason is to have better measure of the Mosfet heating.
increasing the C105 value was my first idea, but this reduce the noise just a little.
 
Your circuit shows it having a ground remote to the MCU. If it wired like that, it could well be ground noise.

Try power and ground connections directly at the MCU, and no connections to anything else away from the MCU.
 
I have used 3 values: 10n, 222n (100+100+22n) and 400n (200+200n). In the final try, I added a 10k R and I have now a better result but not good yet :-I
 
funnyKedougou said:
I have used 3 values: 10n, 222n (100+100+22n) and 400n (200+200n). In the final try, I added a 10k R and I have now a better result but not good yet :-I
Click to expand...
You can go a lot higher than that since the thermistor resistance changes slowly, so even a large RC value won't affect the measurement accuracy.
 
Status
Not open for further replies.

Similar threads

F
  • Question
50 Ohm NTC will degrade over the years?
Replies
0
Views
1K
Flyback
F
M
  • Question
Low noise TEC driver design - adjustable linear voltage regulator
2
Replies
26
Views
7K
Tony Stewart
U
  • Question
Generate continuous random bit stream from noise
2
Replies
20
Views
4K
BobW
B
Is relay paralel to NTC termistor even worth it?
2
Replies
21
Views
5K
MacIntoshCZ
D
IC to Control Fan PWM via Thermistor
Replies
1
Views
2K
Ian Rogers
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…