Resistors

Reading time : 2 minutes
Published on 19 Jun 2020 - Updated on 09 Mar 2021

Normalized values

E3 (± 20 %)
100, 220, 470

E6 (± 10 %)
100, 150, 220, 330, 470, 680

E12 (± 10 %)
100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820

E24 (± 5 %)
100, 110, 120, 130, 150, 160, 180, 200, 220, 240, 270, 300, 330, 360, 390, 430, 470, 510, 560, 620, 680, 750, 820, 910

E48
100, 105, 110, 115, 121, 127, 133, 140, 147, 154, 162, 169, 178, 187, 196
205, 215, 226, 237, 249, 261, 274, 287
301, 316, 332, 348, 365, 383
402, 422, 442, 464, 487
511, 536, 562, 590
619, 649, 681
715, 750, 787
825, 866
909, 953

E96 (± 1 %)
100, 102, 105, 107, 110, 113, 115, 118, 121, 124, 127, 130, 133, 137, 140, 143, 147, 150, 154, 158, 162, 165, 169, 174, 178, 182, 187, 191, 196
200, 205, 210, 215, 221, 226, 232, 237, 243, 249, 255, 261, 267, 274, 280, 287, 294
301, 309, 316, 324, 332, 340, 348, 357, 365, 374, 383, 392
402, 412, 422, 432, 442, 453, 464, 475, 487, 499
511, 523, 536, 549, 562, 576, 590
604, 619, 634, 649, 665, 681, 698
715, 732, 750, 768, 787
806, 825, 845, 866, 887
909, 931, 953, 976

Pulse loads

Resistors have a well known limit for mean power, but they have also a limit regarding power and voltage depending on duration. Here is data extracted from standard SMT resistors datasheet. This can be useful to choose package for resistors that are used to absorb transient loads or ESD.

Single pulse

Maximum single pulse power on a resistor This curve is only valid when average power dissipated inside resistor is close to 0.

Continuous pulse

Maximum continuous pulse power on a resistor This curve is valid when mean power dissipated inside resistor is not null but under allowed average limit but not null

Voltage pulse

Maximum voltage pulse on a resistor This curves gives an idea of maximum allowed voltage on a resistor during small amount of time.

Shunts

Shunts resistors are not really 0 Ohms, typical value for shunts is 50 milliOhms. Theses components are made to be used as configuration straps. It is not recommended to use them on power rails.
If a shunt is absolutely required on a high power trace, use a precision resistor with a known and precise value.