In electronic circuit design, shuntingresistance(Shunt Resistor) is a common measuring element mainly used to measure current. By adding a shunt resistor to the circuit, the current flowing can be calculated by measuring the voltage drop across the resistor. Correct connection of the shunt resistor is crucial to ensure measurement accuracy and circuit safety. This article will introduce in detail the connection method of the shunt resistor and related precautions to help you better understand and apply the shunt resistor.
1. Understand the basic principles of shunt resistorsA shunt resistor is aLow value resistorThe resistor usually has a very small resistance (such as a few milliohms to a few ohms), and its function is to convert the current into a voltage signal proportional to it. According to Ohm's law, voltage = current × resistance, so as long as the voltage across the shunt resistor is measured, the current value flowing through the circuit can be calculated. Since the resistance of the shunt resistor is very small, the impact on the circuit can be minimized.
2. Connection method of shunt resistor - series connectionThe shunt resistor must be connected in series with the current path of the circuit. Generally speaking, a shunt resistor is connected on the circuit line between the power supply and the load, and the current flows through the resistor to form a voltage drop. Only series connection can ensure that all current passes through the shunt resistor and the current value can be accurately measured.
3. Select the appropriate connection location for the shunt resistorThe common access locations of shunt resistors are high-end (power side) and low-end (ground side). The high-end connection method places the shunt resistor on the positive side of the power supply. When measuring voltage, you need to pay attention to the problem of high common-mode voltage. The low-end connection method connects the shunt resistor to the ground terminal. The measured voltage signal is relatively small and the circuit design is simpler. Different connection methods are selected for different application scenarios, and measurement accuracy and circuit complexity need to be weighed.
4. Pay attention to the power and resistance selection of the shunt resistorThe resistance of the shunt resistor should be small enough to avoid causing a large voltage drop in the circuit and affecting the load power supply. At the same time, the shunt resistor must be able to withstand the power flowing through it. The power calculation formula is P=I²×R. Choose a resistor with an appropriate power level to avoid damage due to overheating or measurement errors.
5. Connection method of measuring endThe voltage signal at both ends of the shunt resistor needs to be amplified by a differential amplifier or operational amplifier before it can be accurately read by devices such as a microcontroller. The measurement lines should be as short as possible to avoid noise interference, and shielded wires or twisted pairs should be used to improve signal stability.
6. Connection diagram and actual installation suggestionsDuring specific installation, the shunt resistors should be connected closely to avoid poor contact. The schematic should indicate the direction of current flow, the location of the resistor, and the measurement port. When installing, try to be as close to the load or power supply as possible to reduce measurement errors caused by line resistance.
7. How to connect multi-channel shunt resistorsIn multi-channel current measurement, each load needs to be connected with a separate shunt resistor in series to avoid signal confusion. When measuring multiple channels, the layout should be reasonable to avoid interference and crosstalk.
8. Frequently asked questions and solutionsThe shunt resistor is seriously heated: check whether the power matches and replace if necessary.High power resistor。
The measurement signal is unstable: Check the wiring and shielding of the measurement lines to minimize interference.
Large measurement deviation: Confirm whether the resistance value and wiring method are correct.
：The correct connection of the shunt resistor is an important step in ensuring accurate current measurement and circuit safety. It must be connected in series in the current path, choose the appropriate resistance value and power level, and choose the high-end or low-end connection method according to the actual application. The measurement end should be matched with a differential amplifier to obtain a stable signal. Through reasonable layout and attention to details, the shunt resistor connection method can effectively improve the accuracy and reliability of current measurement. I hope the content of this article can help you better understand "how to connect a shunt resistor" and provide strong support for your electronic design.
