Unlocking Efficient Power Conversion with TMR Current Sensing

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Published June 9, 2026

While much of the conversation around power electronics focuses on the impressive power-handling capabilities of silicon carbide (SiC) and gallium nitride (GaN) transistors, power electronics’ control circuitry is also undergoing an important generational leap.

DC fast electric vehicle (EV) chargers, traction inverters, and high-density DC-DC converters benefit from faster switching speeds that reduce switching losses at high voltages up to 1200V. To take full advantage of the speed of SiC and GaN transistors, control circuitry must also be fast. Traditional Hall-effect sensors often lack the bandwidth and response time needed to capture fast current transients accurately in modern power stages. When sensors lag behind switches, control loops lose visibility, efficiency suffers, and protection mechanisms may react too late.

In this week’s New Tech Tuesdays, we examine how high-bandwidth tunnel magnetoresistance (TMR) current sensors enable faster, more accurate control loops in modern SiC and GaN power systems by capturing rapid current transients that traditional Hall-effect devices miss, improving efficiency, protection, and overall system performance.

In fast-switching systems, current information plays a critical role in real-time control, protection, and optimization. High-bandwidth current sensing provides enough resolution to quickly identify and act on current changes, enabling tighter control loops, more accurate over-current detection, and better visibility into switching behavior that would otherwise be invisible to slower sensors.

As switching frequencies rise, missed or delayed current information can result in increased losses, electromagnetic interference (EMI), or even device stress. This is especially true in applications like EV traction inverters and fast chargers, where transient behavior directly impacts efficiency, reliability, and safety.

The shift toward SiC and GaN demands sensing technologies that offer both speed and precision. Hall-effect current sensors are widely used in power electronics and offer isolation and simple integration, but they are not fast and accurate enough to capitalize on the speed of SiC and GaN. TMR current sensors provide faster measurements than conventional Hall-effect sensors, making them a compelling alternative in applications where minimizing switching losses is a priority.

TMR sensors leverage quantum mechanical tunneling effects to detect magnetic fields with high sensitivity, providing fast and accurate measurements with high isolation from conducting elements.

Compared to Hall-effect solutions, TMR-based sensors can deliver faster response times, enabling designers to accurately monitor rapid current changes associated with modern switching devices. This makes TMR particularly attractive for control loops operating at high frequencies, where timing and accuracy are paramount.

Allegro MicroSystems ACS37100 10MHz TMR current sensors address the sensing challenges of high-speed power electronics head-on. Built around TMR technology, the ACS37100 sensors deliver up to 10MHz of bandwidth, allowing them to capture fast current transients that conventional Hall-effect sensors may miss. Two TMR bridges within the device differentially sense current, helping subtract interfering common-mode magnetic fields (Figure 1). Built-in temperature sensing and compensation maintain stability across the wide operating range of -40°C to 150°C.

Figure 1: Allegro Microsystems ACS37100 TMR current sensors provide fast and accurate current sensing while maintaining safe isolation from the conducting lines. (Source: Allegro Microsystems)

These current sensors provide fast response times suitable for closed-loop control in systems using SiC and GaN transistors, making it a strong fit for applications like DC EV chargers, traction inverters, and high-frequency DC-DC converters. By maintaining accurate current visibility at high switching speeds, the ACS37100 helps designers implement tighter control strategies and more responsive protection mechanisms.

Because the ACS37100 devices are designed specifically for high-speed current sensing, they enable engineers to leverage the performance benefits of wide-bandgap power devices without compromising measurement fidelity or system stability.

As power electronics continue to evolve, sensing technology cannot be an afterthought. Wide-bandgap semiconductors push switching speeds forward, and current sensors must advance alongside them. With TMR-based solutions like the ACS37100 current sensor, designers gain the bandwidth and responsiveness needed to see what is really happening inside fast power stages and get the best performance possible out of power semiconductors.