Magnetics Business & Technology - March/April 2025 - 6

FEATURE ARTICLE
Power-Hungry Automobiles Stimulate Advancements in Magnetic Current Sensing that Apply
Widely to Electrification Markets
New magnetic sensing ICs from Allegro Microsystems deliver higher isolation in a markedly reduced footprint, yielding exceptional power
density for design engineers working EV and other applications.
Led by demands of the electric vehicle market but extending widely
to many other applications, magnetic current sensors are increasingly
replacing sense resistors and current transformers. A few
examples of new magnetic current sensing products illustrate the
rapid-fire developments that are bringing change.
Semiconductor companies Allegro Microsystems and MultiDimension
Technology (MDT) have both developed important new advancements
in integrated circuitry lately but they are by no means
alone as many product developers harness Hall Effect and tunnel
magnetoresistance (TMR) technologies to address the opportunities
for current sensing on different levels, fueling continued advancements
and competition. This article highlights several new
ICs from Allegro and MDT as well as new magnetic current sensor
products and capabilities from others including Littelfuse, Vacuumschmelze
and TDK.
Modern cars have become increasingly power hungry, points out
Allegro. Even the least electrified vehicles include advanced electronics
for infotainment, safety, and engine control. Fully electric vehicles
further add high-voltage power domains to charge and drive.
Each of these systems shares the need for power monitoring and
control, and this is where current sensors are used.
Safety systems and powertrain electrification OEMs are implementing
electrified steering and braking systems to increase vehicle
6 Magnetics Business & Technology * March/April 2025
safety and enable automated driving. These systems encompass
one or more high-current motors to actuate the steering rack or
brake caliper. Safety systems require current sensors to be small
and have low heat generation.
A basic electric vehicle powertrain encompasses a charging system
and a drive system. A charging system may experience 100A at
400V or 800V, while the drive system may need to deliver several
hundred amperes of current to the traction drives. Current sensors
require isolation and high current capability, while also operating
from DC to a high bandwidth for efficient power conversion and system
protection.
Current sensing needs have historically been met using sense resistors
and current transformers, explains Allegro. The sense resistor
(and associated shunt amplifier) provides V=I×R but suffers due to
large size, high power dissipation, slow bandwidth, and no inherent
isolation. The current transformer provides an isolated, high- speed
measurement, but has drawbacks of large component height, no
DC sensing, a narrow frequency band, and needing many external
components to operate.
Magnetic current sensors are non-contacting sensor integrated circuits.
This means the sensor silicon is not touching the conductor
carrying the current. Isolation does not require extra components,
and ranges from 100V to several thousand volts. The sensor meawww.MagneticsMag.com

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Magnetics Business & Technology - March/April 2025

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