For example, AC0603FR-071K21L is marked 09B. “09B” is a resistance code which includes the first significant digits of the resistance value followed by the number of zeros. Using the EIA-96 Making Standard, you can identify the number of zeros from the third letter. Note that “09” is not, itself, the resistance code - this is important! It’s instead used to find the actual resistance value in the datasheet.
According to the Table 2 EIA-96 Marking Rule from Yageo Document “Datasheet Chip Resistors Marking”
- “09” calls out 121 Ohms Value
- “B” calls out the multiplier 1x10
Therefore, this marking code “09B” calls out a resistance value of 1210 Ohm, or 1.21k-ohms.