Detailed explanation of single chip shunt resistor sampling current circuit

In modern electronic design, current sampling is an important means to monitor and control the operating status of the system. As the control core, the microcontroller often shuntsresistanceImplement current sampling to achieve accurate measurement and management of current. This article will focus on the "MCU shunt resistor sampling current circuit" and introduce its principles, design points and application methods in detail to help readers deeply understand the implementation and optimization techniques of this circuit.

Shunt resistor sampling uses a low-value resistor connected in series in the circuit. When current passes through, a voltage drop proportional to the current will be generated across the resistor. The microcontroller collects the voltage signal through the ADC (analog-to-digital converter), and calculates the current value. This method is simple, low-cost and easy to implement, and is a common solution for measuring current by microcontrollers.

The resistance of the shunt resistor is usually small, generally between a few milliohms and tens of milliohms. It is necessary to ensure that the voltage signal is large enough to facilitate sampling, but not too large to cause circuit power loss and heat generation. The smaller the resistance, the lower the power consumption, but the smaller the sampling signal is, so signal strength and power consumption need to be weighed.

When the shunt resistor carries current, it will generate power loss. The power calculation formula is P=I²R. It is necessary to select a resistor with an appropriate power level during design to avoid resistance value changes or damage due to overheating. At the same time, reasonable layout and heat dissipation design are also very important.

The sampling points at both ends of the shunt resistor should be as close to the resistor as possible to reduce wire impedance and interference. The sampling signal line should be shielded or use differential sampling to improve the anti-interference ability of the signal and ensure measurement accuracy.

The ADC input of the microcontroller should have sufficient resolution and sampling rate to adapt to the dynamic range of current changes. The input impedance needs to be matched to avoid affecting the sampling voltage. At the same time, set the ADC reference voltage appropriately to ensure that the measurement range covers the current signal.

Since the amplitude of the signal sampled by the shunt resistor is small, it is often necessary to amplify it through an operational amplifier to improve the signal quality. The filter circuit can filter out high-frequency noise and ensure the stability and accuracy of ADC sampling.

The software part of the microcontroller should filter, convert and calibrate the collected voltage signals. The calibration process includes zero-point calibration and full-scale calibration to ensure the accuracy and stability of the measured values. Algorithms such as average filtering and median filtering can be used to reduce sampling errors.

Shunt resistor sampling current circuits are widely used in battery management systems, motor control, power monitoring and other fields. By monitoring current in real time, the microcontroller can implement overcurrent protection, energy consumption statistics and status diagnosis, improving system safety and reliability.

When designing, attention should be paid to avoiding common ground interference and reasonable wiring to prevent noise coupling. The temperature drift effect of the shunt resistor needs to be considered, and resistance materials with low temperature coefficients should be selected. If the sampling signal is too small, the amplification factor should be appropriately increased or a high-precision ADC should be replaced.

The microcontroller shunt resistor sampling current circuit is widely used because of its simple structure and low cost. Through reasonable selection of shunt resistors, optimized sampling circuit design and complete software processing, high-precision and high-stability current measurement can be achieved. Mastering these core points is of great significance to improving the performance and reliability of electronic systems. I hope that the detailed explanation in this article can help readers better understand and apply the microcontroller shunt resistor sampling current circuit.