hi guys,

I don't really understand thermistors so help required please.

I need one to go between a line filter and a pcb mount SMPS. The max input voltage is 260 VAC. The SMPS is rated at 167mA

The second application is again between line filter and SMPS but this time there are 2 x 420mA SMPS being fed by the line filter.

Can someone please please me select the correct thermistor for both applications.

 

Why do you think you need thermistors?
Not just because nobody else does that, because nobody can select a thermistor for a purpose they don't know.

 

Why do you think you need thermistors?
Not just because nobody else does that, because nobody can select a thermistor for a purpose they don't know.

Looking at the spec sheet for the SMPS the manufacture recommends using one for good EMC practice. The thing is I just don't understand the different resistance levels the come in and why it makes a difference.

 

I think he is asking about surge current limiters such as these:
http://www.digikey.com/products/en?FV=fff4000a,fff80391&k=surge protection

 

the spec sheet for the SMPS the manufacture recommends using one for good EMC practice.

Can you give us a link to the datasheets? Or the model numbers? or the manufacturer's name? or why your product needs EMC compliance? or which EMC regulation you are trying to meet?

 

Do you mean "varistor"?

 

I think he is asking about surge current limiters such as these:
http://www.digikey.com/products/en?FV=fff4000a,fff80391&k=surge protection

Yes that looks like what I am after, just don't know which one I need.

 

Do you mean "varistor"?

The recommendation is a MOV after the fuse but before the filter and a thermistor between the filter and the SMPS.

 

http://docs-europe.electrocomponents.com/webdocs/14ae/0900766b814ae925.pdf

This is the SMPS, I am looking at the EMC application but using a filter that does not have the MOV built in.

 

Yes that looks like what I am after, just don't know which one I need.

I like red ones.

 

Can you give us a link to the datasheets? Or the model numbers? or the manufacturer's name? or why your product needs EMC compliance? or which EMC regulation you are trying to meet?

http://docs-europe.electrocomponents.com/webdocs/14ae/0900766b814ae925.pdf

http://docs-europe.electrocomponents.com/webdocs/141c/0900766b8141c3ba.pdf

The product need EMC compliance because in Europe CE marking is mandatory and EMC testing is part of that. It is an industrial water level sensor. The standard is EN61326-1

 

Here are the part numbers. Now the mystery is, "Who makes them and who sells them?"
External input NTC is recommended to use 12D-5;
External input MOV is recommended to use S14K350

 

Here are the part numbers. Now the mystery is, "Who makes them and who sells them?"
External input NTC is recommended to use 12D-5;
External input MOV is recommended to use S14K350

I have seen the part numbers, the 12D-5 seems to only be available in China and the S14 is obsolete Epcos

 

I have seen the part numbers, the 12D-5 seems to only be available in China and the S14 is obsolete Epcos

You knew the part numbers before you typed your first post?
And it took us an hour to pry them out of you?

I need to go work on something else now.