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All capacitors are measured in Farads. The scale of which they are measured can sometimes be different. If they are measured in Farads, Microfarads, Nanofarads, or Picofarads can be determined by the physical size and type of the capacitor.
Larger parts might spell this outright as the product has the space to do it. When they do there are a couple of things to be careful of.
You may see the units of millifarad referenced as MF instead of mF like the convention tells us it should be. with that said, millifarad is rarely used.
Even though the proper way to call out microfarads would be ĀµF, there will be times that is specified using an āMFDā
As the parts get smaller, the specifications tend to be conveyed by a code. The type of capacitor and the convention of the code used on it will play a part in decoding what it actually means.
These are usually large enough that their specifications will be printed on them but there are expections to this. The most notable example would be the surface mount version.
Standard-tolerance SMD capacitors use a 3-digit code to mark the capacitance value on the part. The first two numbers will indicate the significant digits, and the third will be the multiplier. āRā is used to indicate the position of a decimal point.
To get our value we multiply our significant digits against our multiplier. We simply add that number of zeros on to the end. This value is in picofarads. To change to to microfarads, simply move the decimal point to the left six spaces.
Similar to the three digit EIA, the four digit format uses the beginning values to indicate the significant digits, the last digit as the multiplier and a letter designating a tolerance. āRā is used to indicate the position of a decimal point. The four digit format allows for higher precision.
Sometimes there is so little room on the part that even the standards are not practical. The EIA-198 system of part marking uses two characters (one number and one letter) in which the letter represents the value and number represents the multiplier. There are a couple of things to know.
*This system is case sensitive.
You will notice that by using some of the lower-case versions of letters they could eliminate many of the troublesome numbers such as I and O. They too easily get confused for 1 and 0.
The capacitance codes are not based upon the capacitance value like the others
The first digit is used for capacitance and correlate to the following tables.
Please be aware, While this system is still measured in picofarads, The multiplier code is one more than what we are used to in the other two methods.
I havenāt been able to find an answer to this question, so maybe youāve got it.
Iām trying to identify SMD caps on an existing assembly, and theyāre marked with what appears to be the two-character EIA-198 code, but followed by a caret (^), e.g. A5^ . Any idea what that might indicate? Voltage, manufacturer, tolerance, etc.?
Welcome to the Technical Forum. Can you post pictures with the part markings clearly shown? We can then try to see if we can identify them with the pictures. If you can give dimensions that would be useful also.
No pictures available. Itās just as I described, three characters, thatās all. The one marked A5^ (previously mentioned, and presumably a .1uF) is a 1210. This board is from the late 1980s.
I am not sure what the A5 is. You can look through the .1uf 1210 options we have on the website:
I would try to figure out with the circuit how much voltage this needs to handle. You can narrow the search by the voltage to get less options. If you are unsure you can just choose the highest voltage. Though doing this could make the tolerance worse. I am not sure with the information provided what the voltage would be.
I notified all our technical staff, to see if anyone can identify what this vintage caret symbol ^ would be. Hopefully someone will have knowledge on the importance of what this vintage symbol means. I am hoping we get a response today, but possibly this week sometime as we may have some currently out of office.
Thanks for your patience and look forward to one of our employees to hopefully have more knowledge on this.
I searched alot and will look some more but did notice that AVX uses ^ as a logo sometimes it is filled in like an arrow head and sometimes it is a sharp ^ however it always is on the left of the part but I do not know how they did it in the 80ās ā¦ I will keep looking and update If I find more.
