The resistance of the conductor to the current is called the resistance of the conductor; Resistance is represented by R and the unit is ohm; The greater the resistance of the conductor, the greater the resistance of the conductor to the current.
Resistance is the effect of the conductor on the resistance of the current, R represents resistance, the unit is Ω. The SMD resistance is relative to the color ring resistance. In terms of use, it occupies a smaller PCB area, and the SMD resistor will be used in relatively high-end brand mobile phones.
1 size
The smallest SMD resistor package is 0075, (0.3mm*0.15mm). The package size is required when building a PCB package
2 Voltage
Usually in the application, we have to choose a suitable packaged SMD resistor, which can be based on the actual resistance that may flow.Voltage value and power selection, generally there are two powers in the same package, the larger one is higher than the price of the conventional power.
3 parameters
The following parameters need to be considered when selecting the resistance
1. Nominal resistance, such as 1002 means 10K resistance
2. Error range 10K 1% precision resistance range, (allowable error is the maximum allowable deviation of the resistance value from the nominal value difference)
3. Rated power refers to the maximum allowable power at a certain ambient temperature
4. Rated voltage According to the rated power and resistance, the rated voltage can be obtained
5. Temperature coefficient calculation formula TCR=\frac{R2-R1}{R1*(t2-t1)}*10^6(ppm/℃) TCR=R1?(t2?
t1)R2?R1??106(ppm/℃)
6. Classification Resistance characteristic category (fixed resistance, adjustable resistance, special resistance)
Manufacturing material categories (metal film resistor, wire wound resistor, non-inductive resistor, thin film resistor, thick film resistor), etc.
Installation method category (plug-in resistor, SMD resistor)
Function category (load resistance, sampling resistance, shunt resistance, protection resistance), etc.
Most of the resistance in all electronic products exist, simple and important!