CT40x: Redefining Sensor Performance

The demand for higher performance in industrial applications will most likely lead to a replacement of Hall effect sensors by…TMR sensors, which in turn will have to become more affordable.

– IOPscience Scientific Paper

CT40x: Redefining Sensor PerformanceThe advantages of TMR current sensors over legacy solutions like Hall effect or shunt are well documented. The CT40x revolutionizes current sensing in today’s dynamic and demanding environments with unparalleled performance and exceptional accuracy addressing all contact and contactless current sensing applications.

TMR current sensors are the ideal choice for today’s application demands for high bandwidth, dynamic range, and lifetime performance. TMR sensors boast higher resolution, which means they detect smaller current values in the mA range. They have a wider dynamic range, so they can measure current values with high resolution. And TMR sensors are also more stable over temperature, so they provide more accurate measurements in challenging environments.

So what’s the catch? Price.

Until now.

Crocus Technology has just shattered the price barrier with the release of their CT40x sensors, leveraging ten years of deep XtremeSense® TMR R&D.

The result is a new class of CMOS-compatible sensor <1% total error,500kHz bandwidth, Common Mode Field Rejection, and 3kV Galvanic Isolation. This powerful TMR performance can be factory trimmed, and is available to all markets, especially price sensitive ones that were stuck with low performance legacy-hall. Finally, the transition from Hall has become simple, as CT40x is pin-to-pin compatible with many legacy Hall products.

Like all of Crocus’ TMR sensors, the CT40x maximizes power conversion efficiency with lower heat dissipation and a smaller footprint in power converters. To protect your system, they deliver fast, precise overcurrent detection and optimization by measuring power consumption.


The CT40x caters to a broad spectrum of applications, from low-power devices to high performance systems and will be available in multiple package options for contact current sensing (figures 2 and 3) with an impressive range of ±10A to ±65A.

Contactless CT405x
The Contactless CT405x is capable of high resolution measurements thanks to its high SNR with detectivity at ~ 5μT. It also offers immunity to stray magnetic fields in its differential configuration without the need for shields and concentrators. (figures 4 and 5)
When the powerful performance of TMR is targeted at high-volume, cost-constrained segments, the applications are numerous. (figure 6)
performance of TMR

Why Crocus Excels

Crocus Technology’s unique “three pillar” system (figure 7) ensures a solid foundation that enables industry leading performance and an efficient manufacturing advantage.
  • A Magnetic TMR Stack is expertly designed to provide the exact performance targets of the sensor including sensitivity range, temperature drift characteristics and reliability. Crocus Technology’s dedicated magnetics R&D team, solely focused on TMR development, continues to push the frontier by developing new materials and processes.
  • The Sensor Design leverages the magnetic TMR stack to build a half-bridge or a full-bridge structure using multiple interconnected stacks. This allows for enhanced temperature drift performance and reliability. It also delivers unparalleled noise optimization.
  • CMOS integration gives a decided manufacturing advantage to Crocus Technology enabling monolithic, single die, products, with integrated Analog-Front End (AFE) to leverage the Half or Full bridge TMR sensor design using Crocus Technology’s proprietary circuit design and integration IP.

Why CT40x Wins


  • Immunity to common-mode fields(-40dB)
  • 500 kHz Bandwidth
  • Supports AC & DC Current
  • Ratiometric output from supply voltage
  • Factory-trimmed sensitivity and quiescent output voltage
  • 3V to 5.5V single supply operation
  • Current range ±10A to ±65.0A
  • Typ. Total Error: ±3% FS (-40 ̊C to +125 ̊C)
  • 3kV Isolation
  • Operating Temperature:
    • -40°C to +125°C


  • Immunity to external interference
  • <1% Total error over temperature
  • UL & IEC Isolation Rated

The Crocus Technology Portfolio

These efficient CT40x sensors complete Crocus technologies’ portfolio of TMR Sensors (figure 8), including the CT43X, which focuses on higher end application uses. The CT43x delivers >1MHz, while CT40x performs at 500KHz. Now high performance is available at every price point.


On Key

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