3920 0.004R(4m Ohm) 4W Metal Shunt Chip Resistor: Ideal Choice for High Precision and Strong Surge Withstanding
In modern electronic power systems, current sensing resistors play a critical role. Especially in high-power, high-precision applications, the requirements for stability, temperature coefficient, and surge robustness of resistive components have become extremely stringent. To meet these market demands, the 3920 0.004R(4m Ohm) 4W metal shunt chip resistor (model: ESR39F4WR004F02G) has been developed. Utilizing advanced FeCrAl alloy material and precision manufacturing processes, it achieves ultra‑low resistance, high power density, and excellent reliability, making it an ideal sensing element for power management, motor drives, and battery protection. This article comprehensively introduces its technical parameters, material advantages, electrical characteristics, and environmental compliance.
Recommended shunt resistor: Yineng ESR series
1. Product Overview and Package Benefits
The 3920 0.004R(4m Ohm) 4W belongs to the metal shunt chip resistor family, with a 3920 imperial package size (9.8mm × 5.0mm metric). It delivers 4W rated power in a compact footprint, achieving far higher power density than traditional thick‑film or thin‑film resistors. The resistance value is as low as 0.004Ω (4 milliohms) with a tolerance of ±1%. The suffix ESR39F4WR004F02G identifies its series and packaging configuration. Compared to common current sensing resistors, this product features a shunt structure with uniform metal current paths and extremely low parasitic inductance, making it particularly suitable for current sampling in high‑frequency switching power supplies. Moreover, the 3920 large package provides excellent heat dissipation, and with 4W power capability, it can sustain DC currents from several amperes to tens of amperes without significant temperature rise, laying a solid foundation for long‑term system stability.
2. Core Technology of FeCrAl Material
The core competitiveness of the 3920 0.004R(4m Ohm) 4W stems from its resistive element material – iron‑chromium‑aluminum (FeCrAl) alloy. This alloy offers remarkable advantages: First, its moderate resistivity allows precise control of the 4‑milliohm value, and laser trimming achieves ±1% high accuracy. Second, FeCrAl has excellent oxidation and corrosion resistance, maintaining stable resistance even in harsh environments such as high humidity or salt spray, extending service life. More importantly, the thermal expansion coefficient of FeCrAl matches well with the ceramic substrate, avoiding mechanical cracking over the operating temperature range of -55℃ to +170℃. Compared with common manganin or nickel‑copper alloys, FeCrAl exhibits a more stable crystal lattice at elevated temperatures, with long‑term aging drift below 0.5%, ensuring consistent and reliable measurement throughout the product’s lifetime.
3. Low Temperature Coefficient and High Precision
For current sensing resistors, the temperature coefficient of resistance (TCR) directly determines sampling error under varying temperatures. The 3920 0.004R(4m Ohm) 4W achieves a low TCR of better than 50ppm/℃ thanks to the FeCrAl material. This means that when the ambient temperature rises from 25℃ to 125℃, the resistance change is less than 0.5%, far lower than the 100–200ppm/℃ typical of ordinary alloy resistors. Combined with the initial ±1% tolerance, the total error over the full temperature range is kept within 1.5%, making it ideal for high‑accuracy constant‑current sources, battery management system (BMS) coulomb counters, and current‑loop feedback in servo drives. Additionally, each resistor undergoes 100% pulse testing and resistance screening before shipment, ensuring consistent low‑TCR behavior and traceability for mass production.
4. Excellent Surge Withstanding Capability
In transient overcurrent scenarios such as motor startup, hot‑plugging of power supplies, or lightning‑induced surges, ordinary resistors often burn out or suffer resistance drift due to localized overheating. The 3920 0.004R(4m Ohm) 4W features a reinforced surge‑withstanding structure: the metal shunt has a large thermal mass and cross‑sectional area, capable of absorbing short‑duration pulse currents of hundreds of amperes without fusing. Specifically, it withstands a single surge of 100A for 10ms width with a resistance change less than 1%. Moreover, the shunt and end terminations are integrated via a one‑piece welding process, eliminating the risk of solder joint melting found in traditional resistors. This makes the product exceptionally suitable for phase‑current sensing in brushless DC (BLDC) motors, input overcurrent protection in onboard chargers (OBC) for electric vehicles, and surge suppression circuits in industrial power supplies. Practical tests show that after 1,000 successive surge pulses, the resistor still maintains accuracy within ±2%, demonstrating outstanding robustness.
5. Environmental Compliance and Application Fields
With the increasing environmental requirements in global electronics manufacturing, the 3920 0.004R(4m Ohm) 4W fully complies with RoHS and REACH regulations and is lead‑free. No restricted substances are used in its production, enabling end devices to pass EU CE certification and China RoHS testing. The product is also designated as “low temperature coefficient” (low TCR), further emphasizing its suitability for high‑reliability applications. Typical application areas include:
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New Energy Vehicles: Battery pack current sensing, DC‑DC converters, motor controllers.
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Industrial Automation: Variable frequency drives, servo drives, PLC analog inputs.
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Telecom Power: Base station power modules, load sharing in server redundant power supplies.
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Consumer Electronics: High‑power fast‑charging adapters, protection boards for power tools.
Whether in high‑altitude, strong vibration, or high‑humidity environments, the FeCrAl material and robust package guarantee long‑term, trouble‑free operation.
6. Summary and Selection Advice
In summary, the 3920 0.004R(4m Ohm) 4W metal shunt chip resistor (ESR39F4WR004F02G) combines a compact 3920 package, ultra‑low 4‑milliohm resistance, 4W high power rating, ±1% tolerance, and the low TCR and strong surge immunity enabled by FeCrAl material. It is an optimal choice for medium‑to‑high current sensing applications. At the same time, it meets RoHS, REACH, and lead‑free environmental requirements, aligning with global green manufacturing trends. For engineers designing high‑performance power supplies or motor drive systems, selecting this resistor not only simplifies PCB layout (using the larger pads of the 3920 size for enhanced heat dissipation) but also significantly improves the linearity and long‑term stability of current sensing. It is recommended to use a four‑wire Kelvin connection during prototyping to further eliminate lead resistance effects and fully exploit the high signal‑to‑noise ratio of the 0.004R value. As devices become smaller and power densities increase, such metal shunt chip resistors will gradually replace traditional sensing solutions, and this product is undoubtedly at the forefront of that evolution.
