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Help me make surface mount resistors operate in 5V DC

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dkace

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Surface mount resistors

I want surface mount resistors to operate in 5V dc .
Any suggestions?
D.
 

Re: Surface mount resistors

use bourn resistores 1206, 0805, 0603 0r 402
 

Surface mount resistors

For 5Vdc you can use just about evry SMD resistor avaiable, I think they can all handle more than 5V, so I don't really understand your question.
What are you asking for?
 

Re: Surface mount resistors

The limiting element voltage for SMT resistors is at least 50V, so there is no problem with using them at 5V, as long as they are operated within their power dissipation capability.
 

Surface mount resistors

A rule of thumb is to never stress resistors with over 50% of their power dissipation capability.
Another rule of thumb is to never use resistors over 1Mohm. Resistors over one 1Mohm can easliy break (open circuit).
I have often seen >1Mohm resistors break, while working in a service repair department of a larger consumer electronics company. In this company there's a design rule to never use resistors over 1Mohm and never dissapate more than 50% of the rated power dissapation. These rules increases reliability a lot.
I've seen two times that a new engineer had forgot about the old in-house rule of never desing with >1Mohm resistors., and both times it cause problems with lots of retuned products with a broken (open circuited) resistors. There was never anytinhg else wrong with these defect products than the unmotivated open-circuited >1Mohm resistors.
The resistors was normal carbon resistors, I can't tell if high ohm metal-film resistors has the same weakness.
If more than 1Mohm was required then the engineers should always use two or more resistors in series no mater the voltage over the resistors. This rule has been in this company for many years, but recently one or two new engineers had missed this rule and it caused a lot of extra repairs after a short time. This could easily be avoided if the rule was followed, so there were some persons in the company that wasn't very popular after this.
This is not something you learn in universities, but many years of experience in this comapny had showed that high ohm resistors could easily open-circuit without beeing stressed at all.
 

Re: Surface mount resistors

Pretty much all SMD resistors will be capable of operating at 5VDC. Generally, you're looking at 50V operating voltage. However, the power rating is much more important. I've seen heaps of resistors burn out, not because the voltage was too high, but because it was trying to dissipate too much power. (P = V*I).

In general, power ratings are: 0402(1/16W), 0603(1/10W), 0805(1/8W), 1206(1/4W), 1210(1/3W), 2010(3/4W), 2512(1W), 3616(2W), 4022(3W)
 

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