Sampling resistors are current sampling and voltage sampling. For current sampling, a resistor with a smaller resistance is connected in series, and for voltage sampling, a resistor with a larger resistance is connected in parallel. This type of resistor is divided according to the function of the product. It is used as a reference in function and is often used in feedback circuits. Taking the regulated power supply circuit as an example, in order to keep the output voltage constant, a part of the voltage should be taken from the output voltage as a reference (usually in the form of a sampling resistor).
If the output is high If the output is low, the input terminal will automatically reduce the voltage to reduce the output; if the output is low, the input terminal will automatically increase the voltage to increase the output. It is generally used in power supply products, or the power supply part of electronic, digital, and electromechanical products, with powerful functions. The characteristics of sampling resistors are often seen in many electronic products: sampling resistors are generally divided into plug-in resistors, cement non-inductive sampling resistors, and chip resistors according to the requirements of specific circuit boards. Sampling resistors have low resistance and high precision.
Generally, the resistance precision is within ±1%, and 0.01% precision resistors are used for higher requirements. Most of the plug-in resistors produced by domestic factories are made of constantan and manganese copper. However, the majority of users need high-precision chip resistors to realize the sampling function. This is to meet the production of miniaturized products. automation requirements. There are few manufacturers that can produce resistors with low temperature coefficient, high precision, and ultra-low resistance that meet user requirements. Generally, the resistance value of the sampling resistor will be selected below 1 ohm, which is a milliohm non-inductive resistor.
However, some EBW shunt resistor
resistors have requirements such as sampling voltage, and a large resistance value resistor must be selected. However, the resistance base is large and the error generated is large. In this case, it is necessary to select a high-precision non-inductive resistor (up to 0.01% accuracy, that is, 1/10,000 accuracy), so that the sampled data can be very credible. SMD ultra-low resistance resistors (0.0005 ohm, 2 milliohms, 3 milliohms, 10 milliohms, etc.), SMD alloy resistors, high-power resistors (20W, 30W, 35W, 50W, 100W) and other products, the temperature coefficient can be Reach plus or minus 5PPM.