Signal
Current Sensor
Measure DC or AC current without breaking the wire — Hall-effect and shunt-based options.
What is it?
A current sensor converts the current flowing through a conductor into a measurable voltage signal. Two main technologies: (1) shunt resistor + amplifier — small resistor in series with the load, amp reads the voltage across it; (2) Hall-effect IC — measures the magnetic field around the conductor, completely isolated. Used in motor control, battery management, power metering, and over-current protection.
When do you need it?
- Motor-drive phase-current sensing for FOC (Field-Oriented Control).
- Battery management — measuring charge / discharge current for SoC tracking.
- Power-rail current monitoring for active load balancing.
- Over-current fault detection in industrial drives.
- AC mains energy metering (smart meters, plug-in monitors).
How to pick the right one
- Technology
- Shunt + amp: cheap, accurate at low/medium current, non-isolated. Hall-effect: isolated, no insertion loss, but more expensive and noisier.
- Current range
- Match to your expected current including transient peaks. Hall sensors range up to thousands of amps; shunts typically <100 A.
- Bandwidth
- DC for battery / steady current; >100 kHz for motor PWM.
- Accuracy
- 1-3% typical at full scale, better with offset / gain calibration.
- Isolation rating
- Critical for high-voltage systems. Hall-effect sensors offer kV-level isolation by design.
What Magnias offers
Magnias offers current sensor ICs for motor control and battery management — typically integrated shunt-amp solutions with selectable gain and digital outputs. Consult your FAE for application-specific recommendation.
Common questions
Hall-effect or shunt?
Hall when you need isolation, high current, or zero insertion loss. Shunt for low cost, accurate low-current measurement, and where isolation isn't required.
Why does shunt-based sensing dissipate power?
P = I² × R_shunt. A 100 mΩ shunt at 10 A dissipates 10 W — significant. Pick the smallest shunt that still gives readable voltage at your minimum current.
Can I use a current transformer instead?
Yes for AC only. CTs don't pass DC. Suitable for mains metering but not motor / battery.