How to choose the main parameters of the chip adjustable resistor

What is called a patch adjustable resistor is actually a patch type adjustable resistor, which is often used in communications, intelligent security, instrumentation, digital technology electronic devices, etc. SMD adjustable resistors have many main parameters, models and specifications, so how to choose the model for the main parameters of SMD adjustable resistors, and what basic knowledge and model specifications are there. The okplazas.com web editor summarized five methods of model selection, and I look forward to helping everyone.

Method one, installation

Use surface mount adjustable resistors as much as possible. Surface mount chips are not only highly efficient in production and small in size, but also inexpensive for many applications. In order to save indoor space, surface-mounted integrated adjustable resistors can also be used.

Method two, accuracy

At this stage, the accuracy of selecting resistors is not recommended to exceed 0.1%. The common thick film resistors are all 5%. The accuracy above 1% specifies the resistance, and the thick film resistor is recommended; the accuracy of the following 1% specifies the resistance, and the plastic film resistor is recommended. In the design scheme, there is no need to blindly follow the trend of pursuing the precision of the perfect resistance itself, even if the high-precision resistance is harmed by the natural environment, it will exceed its scope. Therefore, more attention should be paid to the index value of the reliability test.

Method three, the metal material of the lead surface

Sn/Pb or Sn is selected as the metal material of the pin surface, which has good electric welding characteristics and low price. Try to reduce the use of precious metal pins or external-level adjustable resistors.

Method four, derating application

Different types of resistors have different insulating layer materials and curing systems, and there are differences in the derating levels for bearing ground stress (mainly working standard voltage, output power consumption and working temperature), but generally they will be 0.6 times rated The value bears the application under ground stress and does not exceed 0.75 times. Derating application is the most important way to improve the reliability and service life of adjustable resistors. The output power of the resistor depends on the size of the package. The output power of the plastic film resistor is not large, generally less than 1W. When the resistor is used, the output power must be derated.

Method 5: Do not use limit and edge specifications

The limit specification models of the adjustable resistors of each category are not used. For example, the edge specification model with the larger minimum resistance value in the actual series of adjustable resistors.

The above is the main parameter model selection method of the chip adjustable resistor. It is very possible that some people will ask that the SMD adjustable resistor is only one type of adjustable resistor, and how should the main parameters of other plug-in resistors be selected. In fact, the method is exactly the same, only some key points are slightly different. Next time, okplazas.com will be edited for everyone.