Among the technical parameters of various types of resistor, the resistor value of the resistor and the allowable error of the resistor value are the technical parameters that must be identified. The identification method has three different identification methods: digital direct identification method, digital identification method, and color code identification method. As the size of smd resistor is getting smaller and smaller, among these representation methods, the smaller and simpler the marking method, the more popular it is.
When using the digital direct identification method and the digital identification method, the size of the allowable error of the resistor value, or the accuracy of the resistor value, generally
uses uppercase English letters instead of numbers
M, K, J, G, F, D, C, B, A
Respectively, the allowable error of resistor value is:
±20%, ±10%, ±5%, ±2%, ±1%, ±0.5%, ±0.2%, ±0.1%, ±0.05%.
In general, the resistor value digital direct identification method is only used for larger-shaped resistor, because only larger-shaped resistor have enough surface area for direct printing of numbers. When using digital direct identification, in order to prevent the decimal point from being unclearly printed or being neglected because the symbol is too small, sometimes 2.2Ω±10% is expressed as 2R2K, as shown in Figure 2.14. The "R" here is the abbreviation of the decimal point (Round), the last "K" does not mean kn, but-a code that indicates the allowable error level of the resistor value is ±10%. For example, 4.7kn ± 5% can be expressed as 4R7J, where J indicates that the allowable error level of the resistor value is±5%.