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FurkanDursun , 05-04-2020, 09:51 PM

Hello,

I would like to ask one question about the resistor.

I saw several kinds of resistors while I was watching the first part of the Advanced PCB Layout Course.

My question is what is the precise resistors, what is the calibration resistors, what is the serial termination resistor?

What is the difference between them? What case must we use them?

I've been searched on google but I want to learn from this forum. Because this forum includes clever and experienced persons.

Thank you for the response.

FurkanDursun , 05-04-2020, 09:52 PM

TYPO in title- A lot of*

beamray , 05-05-2020, 09:52 AM

I may jump in.
Every resistor has it's tolerance of nominal resistance (ex. 10kOhm+-10%). So precise resistors have small tolerance range, usually less than 0,5%. In most of PCB I use 1 to 5 % tolerance resistors. One may one more precise resistors for analog circuits, jitter cleaners, in PLL loops, and so on. calibration resistors usually used in analog circuits, usually for amplfires' tunning or in filters.
serial terminations used to..terminate lines. Usually one will use general use resistors for that ( 10% tolerance).
https://www.youtube.com/watch?v=OuiVpscr1tE&t=68s - nice video about termination.
Hope it will help.

robertferanec , 05-08-2020, 08:40 AM

Thank you @beamray.

Precise: as @beamray mentioned, these are with smaller tolerance (so the real value of resistor is more accurate). When you buy 100OHM 5% resistor, the real value can be also 95 or 105OHMs. More precised resistor would be 100OHM 1%, so the real value would be between 99 - 101 OHMs

Calibration: I just call them this way, these are also precise resistors, but they are connected to pins which are used to calibrate something (e.g. currents or voltages in some interfaces). So ideally you would like to place them as close as possible to the pins (otherwise the bad connection could influence reliability of that specific interface or feature)

Termination resistors: again, this is about how resistor is connected to a signal. Serial termination = resistor is placed close to output pin to improve quality of the signal.