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Shenzhen Saiyiou Electronics Co., Ltd
Date: 2025-01-13Read: 9
A shunt resistor is a precision component inserted into a circuit to measure current. In an ammeter that uses a sensitive meter head to measure current, a shunt resistor is connected in parallel with the meter head to 'divert' some of the current from the meter head. Nowadays, it is common to "shunt" by inserting resistors into the circuit, which will correspondingly slightly reduce the current and voltage in the circuit. Then, a voltmeter or oscilloscope can be used to measure the voltage drop, and Ohm's law can be used to divide the measured voltage by the resistance value to calculate the current flowing through the circuit.
Application of shunt resistors
The shunt resistor has the advantages of simple design, low cost, and high performance, making it suitable for various applications. They are widely used in the following fields:
Routine testing and measurement:The shunt resistor can be embedded in an ammeter or connected in series with the measured load as an external device. Power supply and industrial equipment:Used for current monitoring and fault detection. Motor drive and control system:Used for measuring and regulating current, optimizing performance. Electric vehicles:High precision monitoring of charging and discharging currents. Mobile devices:Current sensing resistors are commonly used to monitor the current consumption of low current devices. The placement of shunt resistors in circuits In most applications, one pin of the shunt resistor should be placed near the ground side (commonly referred to as "low side current sensing"). This approach will reduce the common mode voltage applied to the voltmeter used to measure the shunt. Designers must be aware that the measured return path cannot be shared or coupled with the AC signal path, as AC signals can introduce noise during measurement. In some cases, grounding the shunt resistor may not be feasible or advisable. For example, recently automotive power designers have considered the advantages of directly connecting the splitter to the power supply, which allows them to quickly detect potential faults on downstream paths and thus has the opportunity to protect the circuit. This of course means that the shunt must be inserted into a non grounded node, so special attention should be paid to observing the common mode voltage specifications of the measurement system used to measure voltage drop.