current sense resistor diagram

How Different Configurations of Current Sense Resistors Affect Performance

Bylydiaczystech@gmail.com

Introduction

Current sense resistors play a vital role in precise current measurement across a wide range of electronic applications—from power supplies to motor controls. However, the configuration of these resistors within a circuit can dramatically impact their performance, accuracy, and reliability. This article explores the most common configurations and how each affects the overall system.

⚡ High-Side vs. Low-Side Sensing

High-Side Sensing

  • Placed between the power supply and the load.

  • Offers better fault detection and system protection.

  • Requires a more complex design due to higher common-mode voltage.

  • May introduce challenges for low-voltage signal processing.

Low-Side Sensinghigh-side vs low-side sensing

  • Positioned between the load and ground.

  • Simpler and less expensive to implement.

  • However, it may not detect certain faults, and can introduce ground disturbances.

📌 Design Tip: Choose high-side sensing for safety-critical applications and low-side for simple cost-sensitive circuits.

🧲 Impact of Kelvin Connections

Kelvin (4-terminal) connections separate the current path and voltage sensing path, which greatly improves measurement accuracy.

Benefits:

  • Reduces error due to PCB trace resistance.

  • Enhances precision in low-ohm resistor designs (e.g., <1 mΩ).

  • Ideal for high-current or precision current sensing applications.

🌡️ Thermal Management and Placement

  • Resistor placement near heat-generating components can lead to resistance drift.

  • Good layout design minimizes self-heating effects and enhances stability.

  • Use resistors with low TCR (Temperature Coefficient of Resistance) for consistent results under load.

📶 EMI and Parasitic Effects

  • High-frequency switching circuits may induce EMI in the sense lines.

  • Long traces and poor layout can cause parasitic inductance, distorting fast transient measurements.

  • Shielded traces and proper ground referencing help mitigate noise issues.

✅ Conclusion

The performance of current sense resistors is not only defined by their material and size, but also how and where they are implemented in a circuit. Choosing the right configuration—be it high-side, low-side, or Kelvin-sensed—can significantly affect your system’s accuracy, thermal stability, and EMI robustness.

For high-precision applications, always evaluate configuration trade-offs during the design phase. The right setup ensures safer, more efficient, and longer-lasting electronic systems.