New Current-Sensor ICs Check the Pulse of Power Electronics

Oct. 13, 2023
Can current-sensor ICs win out against the shunt resistor and other passive components? Check out some of the latest offerings on the market in this Products of the Week gallery.

For any electronic control system, current sensing is one of the most important forms of performance feedback. Whether the current measurements are used for real-time protection (against short circuits and other surges of current), control loops (e.g., peak-current mode or average-current mode control in power electronics), or power management (e.g., charging and discharging high-voltage battery packs), understanding the ins and outs of the current traveling to loads is vital.

A wide range of current-sensing technologies exist, each one with a long list of pros and cons that must be considered in the context of the overall system and the environmental conditions it is operating in.

But the most common method for measuring current is to put a shunt resistor—also called a current-sense resistor—in the path of the load. Depending on the resistance value, the device outputs a voltage signal that’s proportional to the current traveling through it. Using Ohm's Law, where the relationship of voltage equals current times the resistance (V = I × R), and assuming a stable resistance, the voltage signal can be used—once it’s sufficiently gained and conditioned—to interpret the current.

Shunt-based current sensors are so widespread thanks to their ease-of-use and ability to accurately measure AC and DC currents from milliamps to several hundred amps. While they come with a wide range of form factors and resistance values, shunts can struggle to handle large amounts of power and aren’t galvanically isolated. Thus, they’re not the best fit for every situation. But current transformers and other passive components can fill in for them in many cases.

As power levels continue to rise in everything from electric vehicles (EVs) to solar and other renewable-energy systems to new power-hungry AI processors inside vast data centers, semiconductor companies think they can do better. Allegro Microsystems, ROHM Semiconductor, Texas Instruments, and many others are rolling out current-sensor ICs that they say bring more to the table than traditional passives. In this product roundup, we will review some of the latest offerings to hit the market.

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