A low value current shunt is a resistor device used for precise measurement of large currents. Its core principle is to indirectly calculate the current flowing through the circuit by measuring the voltage drop across the resistor (Ohm's law \ (I=V/R \)). Its resistance is usually extremely low (in the milliohm range, such as 0.1m Ω to 100m Ω) to minimize power loss and adapt to high current scenarios.
1、 Core Structure and Materials
Material selection:
Manganin alloy: Low temperature float (TCR as low as ± 20ppm/℃), corrosion-resistant, widely used in precision splitters.
Nickel chromium alloy: resistant to high temperatures, suitable for industrial environments.
Copper alloy: Low cost, but requires coating treatment to reduce temperature sensitivity.
Structural form:
Surface mount (SMD): such as 2512 and 1206 packages, suitable for PCB integration (such as consumer electronics).
Metal strip type: high-power design, fixed by bolts (such as electric vehicle battery management system).
Four terminal (Kelvin connection): Separate the current path from the voltage detection terminal, eliminate lead resistance errors, and improve accuracy.
2、 Key performance parameters
|Parameters | Description | Typical Values|
|Resistance range | Extremely low resistance value, avoiding significant impact on circuit power consumption | 0.1m Ω -100m Ω|
|Rated current | Maximum continuous operating current, to match application scenario | 10A – 1000A+|
|Accuracy | Resistance tolerance, high-precision splitter can reach ± 0.1% | ± 0.1% - ± 5%|
|Temperature coefficient (TCR) | Resistance drift caused by temperature changes, requiring low-temperature drift materials | ± 20ppm/℃ - ± 100ppm/℃|
|Power dissipation | The power that the resistor can withstand (P=I ² R), requiring heat dissipation design under high current | 1W-100W+|
3、 Core application scenarios
Battery Management System (BMS):
Monitoring the charging and discharging currents of electric vehicles and energy storage systems directly affects the battery life and safety.
Industrial power supply and motor control:
Real time feedback of current in frequency converters and servo drives to achieve closed-loop control.
Renewable energy system:
Current detection of solar inverters and wind power converters to optimize energy conversion efficiency.
Consumer Electronics:
Fast charging adapters, overcurrent protection and power management for laptops.
4、 Selection and Design Considerations
Resistance and power matching:
Calculate the resistance value (R=V_ {sense}/I2 {max}) based on the maximum current (I2 {max}), ensuring that the voltage drop is measurable (usually 50mV100mV) and the power (I ² R \) does not exceed the device limit.
Temperature management:
High current scenarios require the use of heat sinks or forced air cooling to prevent resistance drift caused by temperature rise.
PCB layout optimization:
The four terminal shunt needs to be independently wired to avoid interference from the main current in the detection path (Kelvin connection).
Signal amplification and processing:
Low voltage signals need to be amplified by high-precision operational amplifiers (such as instrumentation amplifiers) and sent to ADCs to reduce the impact of noise.
5、 Comparison with other current detection technologies
|Technology | Advantages | Disadvantages | Applicable Scenarios|
|Diverter | Low cost, high accuracy (± 0.1%), fast response | Generating power loss, requiring isolation design | High current, high-precision measurement (such as BMS)|
|Hall sensor | contactless, lossless, isolated measurement | high cost, susceptible to magnetic field interference, low accuracy | ultra-high current (>1000A)|
|Current Transformer | Strong Isolation, Suitable for AC Measurement | Limited to AC, Low Frequency Response | Power Grid Monitoring, Industrial AC Systems|
6、 Industry leading brand
Isabellenh ü tte (Germany): Precision micro European grade splitters (such as BVS, IVT series) used in automotive and industrial applications.
Vishay (USA): WSBS and WSLP series patch splitters, suitable for high-density PCB design.
TAI (Dayi, Taiwan): Anti sulfide alloy resistor, suitable for harsh environments.
SUSUMU (Japan): Thin film precision splitter, medical and aerospace fields.
Low resistance shunt is a key component for high-precision current detection, which balances the requirements of low power consumption, high precision, and reliability through material science and structural design optimization. In the fields of new energy, electric vehicles, and industrial automation, its role is irreplaceable. When selecting, it is necessary to comprehensively consider the current range, temperature drift, packaging form, and signal processing scheme to ensure the optimal match between system performance and cost.