# obtaining 1206 chip resistor voltage rating

1. ## obtaining 1206 chip resistor voltage rating

Isnt it simply V=sqrt(P*R) thus a 1k chip resistor rated to 250mW would have a voltage rating of sqrt(1e3*.25) = ~16v ?

Does this mean that even at 1uA the resistor cannot handle anything beyond ~16v?

Trying to figure out how to determine ebay 1206 resistor voltage rating because they aren't specified.

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2. ## Re: obtaining 1206 chip resistor voltage rating

Resistors have a wattage limit and a package or element limit. Package limits typically begin at 25-50V. Generally I’d expect 1206 to handle 50V minimum.

But check the data sheet of course.

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3. ## Re: obtaining 1206 chip resistor voltage rating

Isnt it simply V=sqrt(P*R) thus a 1k chip resistor rated to 250mW would have a voltage rating of sqrt(1e3*.25) = ~16v ?
A very interesting observation indeed. You are right that a 1k 250mW resistor cannot have more than 16V on a continuous basis. But you ignore transient effects.

Say I apply 1kV pulses every second for 1us; then the power will be only 1mW (for the same 1k resistor)- within the safe limits, right?

But the small physical size may not stand 1kV even for 1us; it may cause breakdown (internal or external; but that is not the main point). You will need a resistor with a larger body (perhaps).

That is what we commonly understand by the voltage rating; it is not related to the power consumed.

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4. ## Re: obtaining 1206 chip resistor voltage rating

Does this mean that even at 1uA the resistor cannot handle anything beyond ~16v?
Considered ohms law? 16V across 1k resistor causes 16 mA of current, isn't it?

Voltage rating is relevant for higher ohmic chips. Even if the voltage rating isn't specified for noname products, you can refer to ratings of similar major manufacturer types. A typical spec is 150 or 200V operation voltage for 1206 thin film chips.

Breakdown voltage spec. typically > 300V for standard types. Notice that special high voltage types are available in 1206 from some manufacturers.

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5. ## Re: obtaining 1206 chip resistor voltage rating

As per my understanding, Resisters won't have voltage rating for operational purposes, they will have only Current limt/Wattage limit not the voltage limit. Voltages will be indirectly handled.
They will maximum voltage which can cause resister material will break down. This is not for operational purposes it is for safety or breakdown specification.
What is your application, why you are targeting for voltages.

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6. ## Re: obtaining 1206 chip resistor voltage rating

As per my understanding, Resisters won't have voltage rating for operational purposes, they will have only Current limt/Wattage limit not the voltage limit. Voltages will be indirectly handled.
They will maximum voltage which can cause resister material will break down. This is not for operational purposes it is for safety or breakdown specification.
Not true. As already mentioned, resistors have both, maximal operational and breakdown voltage, e.g. 150 and 300V for 1206 chips. The operational voltage becomes relevant for resistance values above 100k. Exceeding the operational voltage may cause degradation and resistance drift.

7. ## Re: obtaining 1206 chip resistor voltage rating

Hi,

As per my understanding, Resisters won't have voltage rating for operational purposes, they will have only Current limt/Wattage limit not the voltage limit.
No need for "understanding", "guessing" ....
Just look into a common 1206 resistor datasheet: YAGEO/PHYCOMP RC1206 series

On the following datasheet pages they even explain the different specifications and give additional inormations like test methods.

Klaus

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8. ## Re: obtaining 1206 chip resistor voltage rating

Got it. I agree with you.

Klaus, can you tell me is this package specification or every resister has specific voltage value.

What i want to say is,
I say it is package specification/family specification. Not related to resister value.
Resister's purpose is current limit/control (basic purpose), so, specifications needs to be considered are current & power handling.

For a 2 Ohms resister, and 200 Ohms resister in same family(0.25W), actual operational voltage will be different (SQRT(power*R)). But maximum voltage will be same.

For a resister, current, Resistance & power specifications will define indirectly voltage specifications(for operation).

"Does this mean that even at 1uA the resistor cannot handle anything beyond ~16v?"
@ 1uA with 1K resistance , V=IR = 1mV is the voltage drop across. You consider powers @ 1uA with 1K - power disspated = 1nW, it can handle many times more power than this.
please take more care more about power dissipation, unless these resisters used in high voltage transient environments,
In that case consider worst case transient across resister (across is must) and frequency of transients - then calculate transient thermal characteristics like what will be the average power, temperature rise with such frequency of transients.

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9. ## Re: obtaining 1206 chip resistor voltage rating

Voltage rating is partly dependent on resistor technology, not only package dielectric strength. That's one reason why you see so many different specifications, the other is different safety margins.

Dynamic rating is even more complicated.

10. ## Re: obtaining 1206 chip resistor voltage rating

Voltage rating is partly dependent on resistor technology, not only package dielectric strength.
In addition, I would like to mention that the mounting, in this particular case, the PCB solder pads, the substrate material, residual flux, the solder resist also work to reduce these limits. If the underlying design is lacking in resistance, the overall voltage rating of the resistor will be severely compromised.

But then the original objective of the question remains unclear.

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