Hall Effect against Shunt Sensing on the High Side
High-side shunts deliver superior low-current accuracy under high temperatures, while integrated Hall sensors reduce high-current thermal power loss.
Current Sense Resistor
Resistive Transduction
Inline electrical conductors designed to produce a measurable voltage drop proportional to the flowing current provide the fundamental means for monitoring power distribution in sub-circuits. Employing a current sense resistor allows systems to convert high currents into millivolt-level signals for amplification. The devices operate on Ohm’s law where the resistance value is kept low to minimize power dissipation.
Accuracy is limited by the initial tolerance and the stability of the resistive material under load.
Terminal Configuration
Connections with four distinct terminals separate the current path from the voltage measurement circuit to eliminate the resistance of the lead wires. In a high-current path, a standard two-terminal current sense resistor introduces contact resistance errors that skew the voltage reading. The four-terminal Kelvin structure bypasses these contact resistances by routing the sensing lines directly to the resistive element.
This configuration isolates the feedback loops and preserves measurement integrity.
Temperature Sensitivity
Thermal drift in the resistive alloy changes the resistance value as current heats the component or ambient conditions fluctuate. The temperature coefficient of resistance determines the magnitude of this drift, typically measured in parts per million per degree Celsius. Metal strip and metal alloy elements offer lower coefficients than thick-film alternatives, preventing measurement divergence at high currents.
Heavy copper terminals draw heat away from the active region to maintain stable operation. If the resistor operates beyond its rated temperature boundary, the thermal stress causes permanent resistance shifts, destroying the calibration accuracy and leading to system-wide overcurrent false alarms.
Parasitic Inductance
High-frequency circuit applications require minimal internal inductance to prevent voltage spikes and phase shifts during rapid switching events. When current changes rapidly, the parasitic inductance of a current sense resistor generates an unwanted inductive voltage component. Using metal plate geometries reduces this self-inductance to sub-nanohenry levels.
Fast-switching power converters depend on this low inductance for accurate feedback.