Comprehensive Introduction to 3920 0.005R(5m Ohm) 3W Metal Shunt Chip Resistor

Comprehensive Introduction to 3920 0.005R(5m Ohm) 3W Metal Shunt Chip Resistor

Recommended shunt resistor: Ellon ESR series

In modern electronic design, current sensing accuracy and power handling capability are critical. The 3920 0.005R(5m Ohm) 3W metal shunt chip resistor (model: ESR39F3WR005F02G) is an excellent component designed to meet high‑power, high‑precision current sampling requirements. Featuring a large 3920 package, an ultra‑low resistance of 0.005R (5 milliohms), a rated power of 3W, and a tolerance of ±1%, it is an ideal choice for power management, battery protection, motor drive, and many other applications. This article provides a detailed analysis of the core technical characteristics, material advantages, environmental compliance, and application scenarios of the 3920 0.005R(5m Ohm) 3W.

1. Basic Parameters and Package Advantages

The 3920 0.005R(5m Ohm) 3W follows the standard metric 3920 package (equivalent to imperial 1505, approximate dimensions 10.0mm × 5.0mm). The large footprint effectively enhances heat dissipation. With a resistance of 0.005Ω (5 milliohms), the extremely low value minimizes voltage drop when carrying high currents, thereby reducing power loss. A rated power of 3W means this resistor can continuously handle up to 24.5A (calculated from P=I²R, I=√(3/0.005)≈24.5A). Meanwhile, the ±1% initial tolerance ensures consistency in current sensing, which is vital for systems requiring tight error control. The “F” in the model number denotes 1% tolerance, and “R005” directly indicates the resistance value for clear identification.

2. FaCrAl Alloy Material: The Performance Foundation

The core technology of the 3920 0.005R(5m Ohm) 3W lies in its resistive element made of FaCrAl (iron‑chromium‑aluminum) alloy. This alloy offers several outstanding benefits:

• Extremely low Temperature Coefficient of Resistance (TCR) : The TCR of FaCrAl can be as low as ±50ppm/°C or less, allowing the 3920 0.005R(5m Ohm) 3W to exhibit minimal resistance variation over the operating temperature range of -55°C to +155°C, fulfilling the “low temperature drift” requirement.

• High oxidation and corrosion resistance : The alloy forms a dense aluminum oxide protective layer that resists moisture, salt spray, and other harsh environments.

• Excellent surge withstand capability : Compared to conventional thick‑film resistors, the bulk‑structured FaCrAl alloy has higher heat capacity and melting point, absorbing transient high‑current shocks without resistance drift or open‑circuit failure. This is crucial for surge protection at power inputs.

3. High Precision and Low Temperature Drift

For current sensing applications, resistor precision directly determines measurement accuracy. The 3920 0.005R(5m Ohm) 3W offers a standard ±1% tolerance, and higher precision (e.g., 0.5%) can be achieved through selection. More importantly, its low TCR ensures that accuracy remains stable across temperatures. Assume an ambient temperature rise from 25°C to 125°C (100°C delta). With a TCR of ±50ppm/°C, the resistance change is only ±0.5%, which is well within the 1% initial tolerance. Therefore, the 3920 0.005R(5m Ohm) 3W serves as a high‑precision shunt for temperature‑sensitive closed‑loop control circuits such as battery fuel gauging and motor phase current sensing.

4. Surge Withstand Capability Explained

Surge current is a common destructive factor in electronic systems. The 3920 0.005R(5m Ohm) 3W, thanks to its monolithic FaCrAl alloy construction (rather than the granular structure of thin‑ or thick‑film resistors), offers far superior surge immunity compared to standard chip resistors. When a surge occurs, the resistive body heats uniformly, avoiding local hot spots that could cause burnout. Actual tests show that this series can safely withstand short‑term overloads several times its rated power. For example, with a 10ms pulse width, the 3920 0.005R(5m Ohm) 3W can tolerate peak powers up to 100W without failure. This makes it especially suitable for capacitor pre‑charge circuits, hot‑swap protection, and motor drive loops with inductive loads.

5. Environmental Compliance and Certifications

The 3920 0.005R(5m Ohm) 3W fully meets international environmental regulations:

• RoHS : Free from lead, mercury, cadmium, hexavalent chromium, PBB, PBDE, and other hazardous substances.

• REACH : Does not contain any SVHC (Substances of Very High Concern) listed chemicals.

• Lead‑free and environmentally friendly : Terminations use lead‑free plating, and the soldering process is RoHS‑compatible. It also meets halogen‑free standards (Cl ＜900ppm, Br ＜900ppm).
  These certifications ensure that the 3920 0.005R(5m Ohm) 3W can be freely sold in environmentally regulated markets such as the EU, USA, and Japan, while also meeting green product labeling requirements. Additionally, the manufacturing process is certified under ISO14001 for environmental management, further reinforcing sustainability.

6. Typical Application Fields

With the above characteristics, the 3920 0.005R(5m Ohm) 3W is widely used in:

• Switching power supply output current sensing : In DC‑DC converters, it serves as a high‑side or low‑side shunt resistor, feeding back to the control IC for constant current or current limit protection.

• Battery management systems (BMS) : In power tools and energy storage batteries, it monitors charge/discharge current in real time to prevent overcurrent or short circuits.

• Motor drivers : It senses phase current for closed‑loop regulation in FOC (field‑oriented control) or trapezoidal commutation algorithms.

• Automotive electronics : Such as on‑board chargers and DC‑Link capacitor pre‑charge circuits that must withstand high temperatures and transient surges.

• Telecom equipment : Hot‑swap protection circuits in base station power modules.

7. Conclusion

In summary, the 3920 0.005R(5m Ohm) 3W ESR39F3WR005F02G metal shunt chip resistor combines comprehensive advantages: a large 3920 package, 5 milliohm low resistance, 3W high power, 1% high precision, FaCrAl alloy construction, low temperature drift, strong surge withstand capability, and RoHS/REACH/lead‑free environmental compliance. Whether for design engineers selecting components or procurement teams sourcing parts, this product is an excellent choice for high‑reliability current sensing solutions. Its outstanding performance parameters and environmental compliance make it an irreplaceable role in high‑power electronic equipment. For further technical documents or sample support, please contact the original manufacturer or authorized distributors.