Hello,
I am working on Ionization smoke dedector.
Schematic and pcb layout are attached.
I use RE46C152 ionization type smoke detector IC.
Problem is that when dedector operate, It gives alarm although there is no smoke.
I think it's about PCB layout that I draw, but I could not figure it out.

 

Can't open your files...post the circuit diagram please in. Pdf or. Doc

 

Hello,

I can not read the files.
Probably many on this forum can't read the files.

Post the schematic and PCB as screenshot of the project, if it can not export to an other format.

Bertus

 

hi,
I uploaded schematics and pcb drawing.I've hidden the GND polygon on "PCB.PNG"

 

Hello,

I can see the guardring on the PCB, but I do not see the sensor output.
The sensor output should be within the guardring.
In the datasheet there are schematics with guardrings shown.
Unfortunately they do not show an example PCB layout.

Bertus

 

Pins 15,16 are Guard Shield pins to prevent false triggering, the detect pin is 14, its probably the PCB design that isn't providing enough shielding.

Personally I would use an Optical design, never keen on Ionasation types....

 

Hello,

I can see the guardring on the PCB, but I do not see the sensor output.
The sensor output should be within the guardring.
In the datasheet there are schematics with guardrings shown.
Unfortunately they do not show an example PCB layout.

Bertus

Hi,
The sensor output is connected to ion smoke chamber sense pin directly.
The groudn polygon is close to guardrings.I'm worried that this is a problem, but I am not sure

 

Pins 15,16 are Guard Shield pins to prevent false triggering, the detect pin is 14, its probably the PCB design that isn't providing enough shielding.

Personally I would use an Optical design, never keen on Ionasation types....

Hi,
My optical smoke sensor design has worked fortunately.But I have to operate the ion detector.
I doubt about the ground polygon clearance.