High precision resistors in precision circuit design - shunt resistors

Selection of shunt resistor

The function of resistance in electronic circuits is nothing more than voltage division, shunt, and current limiting. Two resistors are connected in parallel, with equal voltage on each resistor and different resistance values and currents. Resistance parallel shunt, the larger the resistance, the smaller the current, achieving the effect of shunt. Shunt resistors can guide the current in a circuit to different branches. When it is necessary to control the current size, the appropriate shunt resistor value can be selected to control the current size in different branches, thereby meeting specific circuit requirements.
The more precise the circuit control is required in a scenario, the higher the precision and reliability requirements for the shunt resistor. In addition, with the improvement of electrical equipment functions, the installation density on circuit boards is increasing, which requires smaller volume and higher rated power of shunt resistors. In industrial and automotive scenarios, achieving high current detection accuracy through shunt resistors also places great emphasis on the high-temperature performance of devices.
In actual current detection, the shunt resistance value is often low, ranging from hundreds of micro ohms to hundreds of milliohms, and needs to be paired with operational amplifiers or differential amplifiers to improve the sensitivity and accuracy of detection. Otherwise, the voltage drop will be too small, making it difficult for the MCU to detect the voltage. There are many typical applications, such as overcurrent protection, 4-20mA systems, battery level detection, high brightness LED control, motor control, and so on.
When selecting a shunt resistor, it is also necessary to be very careful. Firstly, the resistance value must be determined based on the circuit requirements and the required current size. Nowadays, many circuit boards require a higher rated power of the shunt resistor, and it is necessary to choose an appropriate power capacity. If the power capacity is too small, it will cause the shunt resistor to overheat, while if the power capacity is too large, it will unnecessarily increase the circuit cost and volume.
Temperature is also a consideration, and the impact of temperature on device performance should be minimized as much as possible. In addition, accuracy and voltage resistance are also parameters that need to be determined when selecting a shunt resistor. In high current sampling, it is necessary to ensure that these parameter indicators meet expectations and ensure long-term stable device performance.

A shunt resistor that provides miniaturization and energy-saving assistance for application products

In the fields of battery management systems, power equipment, industrial control equipment, and automotive electronics, shunt resistors are widely used. Appropriate shunt resistors can effectively provide miniaturization and energy-saving assistance for application products.
Not long ago, ROHM launched three new products with a rated power of 5W and resistance values of 0.5m Ω, 1.0m Ω, and 1.5m Ω in the standard 6432 size metal plate shunt resistor PMR100 product lineup for applications such as motor control circuits and power circuits in automotive equipment, industrial equipment, and consumer electronics.
These new products use new materials with excellent temperature characteristics and pin temperature reduction, which enhances the rated power capacity and provides larger power products with smaller dimensions, making it convenient for miniaturization of application equipment. At the same time, ROHM's unique non adjustable resistance structure design suppresses the temperature rise problem caused by local current concentration, and its performance can be said to be a benchmark in the industry.
The replacement space for domestic resistors is now quite broad, and many domestic enterprises are rapidly launching attacks on the high-end market. Like the Ruisi brand under Kaibu Electronics, it has a high current and high-precision shunt resistor product matrix, with current capacity ranging from 10A to 20000A, overall accuracy of ± 0.5%, and temperature drift not exceeding ± 100ppm. The high rated current, low temperature drift, and high-precision characteristics can also perfectly cover various power equipment and industrial control equipment.
Focusing on precision micro resistance resistance, Sime Microelectronics has demonstrated the high performance of domestic resistors in shunt resistors with its unique structure and process design. Its shunt resistor series has launched automotive grade products, such as APSRP25, with a TCR of ± 75-250 and power levels covering 5-7W. Technological breakthroughs in materials, design, manufacturing technology, and other aspects have led to the continuous evolution of its products in high-precision, miniaturization, high-power, and other aspects.

Summary

With the trend of miniaturization and energy conservation in various electrical equipment, the role of shunt resistors is becoming increasingly important. The continuously improving performance of shunt resistors will bring convenience to the energy-saving and miniaturization of application products.