by Richard Dixon, iSuppli

March 11, 2010 – Back in February 2009, iSuppli’s MEMS and sensor team reported on trends in the automotive magnetic sensor market, and has since completed a comprehensive report on the whole market for silicon magnetic sensor elements and ICs — predominantly Hall, asymmetric magnetoresistive (AMR) and giant magnetoresistive (GMR) based devices. This article provides the cliff notes of our special report and briefly compares different technologies and highlights just some of the many applications for this very pervasive sensor.

Where do these sensors play? The fields are broad and include:

• High-cost applications like industrial motors that require accurate knowledge of rotor position to control loads
• Mid-priced automotive sensor ICs that measure rotation speed angle, and position
• Low-cost consumer and mobile phone products

Because of this wide variety of uses and products, pricing for such sensor ranges from less than $0.10 for simple switches to $0.50 for automotive sensors like wheel speed sensing up to several US$ for sophisticated programmable sensor ICs used in automotive or industrial motor control.

By technology, Hall sensor elements and sensor ICs make up by far the largest part of this market. A smaller proportion of the market for silicon sensors is for AMR ICs targeting higher performance markets, while a very small fraction of the market is served by GMR sensor ICs and switches, which will emerge over the next four years. iSuppli has also examined tunneling magnetoresistive (TMR) sensors and MEMS magnetic switches, but today these devices respectively serve closed markets for read-write heads or niche medical.

Hall dominates a tough market space

Silicon devices have many competitors. In particular, the Hall sensor IC — a low-cost CMOS based device that benefits from high-volume batch processing, integration of electronics, and non-contact operation — must fight on price with established, low-cost incumbents including potentiometers, microswitches, and Reed switches, not to mention inductive and optical approaches. For certain applications such as steering wheel angle measurement (used for vehicle dynamics systems), the number of competing solutions can be five or more.

But silicon solutions, whether Hall effect or magnetoresistive, are increasingly taking market share from incumbent solutions which can no longer compete as the demands on performance grow — to reduce the emissions in cars, or to make smaller, highly-integrated sensors for the densely packaged PCBs of handsets. The more exotic 2-chip magnetoresistive, e.g. AMR and GMR (which can be single-chip) devices cost more than Hall mostly for processing reasons but perform better and find their way into applications where performance outweighs cost, particularly the automotive and industrial markets, for example.

Hall devices also extend their performance using various techniques that concentrate the magnetic field and allow more axes of measurement (simple Hall is only sensitive to the perpendicular magnetic field) such as with AMR. This has led to 3D joysticks that begin to serve manual (and automotive) transmissions for gear selection, or as an advanced PC mouse or gaming interface. Another trend is the use of linear Hall sensors to replace two or more (Hall or other) switches.

Hockey stick

Following a flat period in 2007 to 2008, the silicon magnetic sensor market is set to commence a period of strong growth in 2010 as demand surges from the automotive, industrial and consumer markets. As we reported in our last issue, 2008 and especially 2009 were very bad years for sensors, and the expected inflexion would have happened earlier — in 2009 — if it were not for the recession which afflicted many markets.

Figure 1. Market by segment for magnetic sensors 2006 to 2013. (Source: iSuppli)

Global silicon magnetic sensor revenues are projected to reach US$1.36 billion in 2013, up from $821 million in 2009, a CAGR of 13%. This equates to slightly more than five billion magnetic sensor ICs and switches, up from about 2.8 billion units in 2009. So, what is driving the market in the next four years?

Generally, the fast pick-up in shipments that began in the second half of 2009 and will now accelerate in 2010 and 2011 is a result of the refilling of inventories as the demand comes back online in automotive — but also as consumer confidence grows and sales of all kinds of consumer goods recover and indeed grow overall, as predicted by iSuppli analysts. In fact, the magnetic sensor market only fell by -6% compared to the whole silicon industry, which was down by -12% overall, largely on the strength of the varied application supply base. Some applications are covered below.

Automotive applications drive sensor sales

Many sensors are needed in today’s cars, and many more will be required in the future. The body and powertrain segments show the greatest potential for new magnetic sensor penetration and will be important target markets for silicon sensors in the future. In the automotive body segment alone, the number of magnetic sensors and switches will grow from 6.7 on average in 2008 to 9.4 in 2013.

Figure 2. Applications for magnetic sensors in today’s cars. (Source: iSuppli)

In engine management, emissions regulations require crankshaft and camshaft rotation speed sensors to be increasingly precise — and older technology such as inductive sensors will no longer make the grade. One reason is that such devices cannot measure position at zero rotation and need high speeds for precision. This is good news for Hall and AMR sensors, and even GMR in the future. Many other sensors are needed for position sensing of turbochargers, which will grow as engine downsizing gains in popularity, in addition to exhaust gas recirculation, electronic throttle position, etc.

Hall or other sensors are used to indicate the gear position at stop in a manual transmission. As transmissions become more sophisticated and the requirements of efficient operation grow, more sensors will be used for position and ration speed, not just in automatics.

In the body (cabin) domain there are over 35 applications and growing for sensors and switches, mainly Hall is competing with low-cost microswitches, Reed switches, and potentiometers. Brushless DC motors are a major user of sensors when loads need to be measured, i.e. in an electric window. Stop/start systems are another interesting application that is gaining in significance.

Consumer electronics and appliances

Major categories for magnetic sensors include:

• Mobile phones
• White goods (washing machines, dishwashers, refrigerators, coffee machines….)
• Personal electronics (cameras, camcorders, MP3 players…)
• Audio / video / gaming
• Desktop and mobile PCs, external HDD, servers…

Inexpensive switches are needed to indicate when a washing machine or refrigerator door is shut, or a folding display in a phone, notebook, or digital camera is open to control the display and save power, or to adjust motors that help a deliver sharp, blur-free pictures.

Figure 3. AMR sensors attach to the spray arm in a dishwasher to detect jamming. (Source: Danby)

Linear sensors and switches are used to provide fluid levels in automatic coffee dispensers found commercially or in the home. Meanwhile, mobile phones use sensors to control the display in clap and sliding phones and in emerging camera autofocus systems for linear position. PCs are another huge source for magnetic sensors.

Cell phones are a key device for magnetic sensor ICs and switches, especially because of the overall size of the market. The abovementioned display control is augmented by emerging applications for camera phone dust-cover status switches, angular sensors to detect the angle of a swivel display phone, and linear sensors for auto-focus and zoom functionality. Generally these are very low-cost sensors in the single-digit $US cents range.

Electronic compass is a market hit in 2009

A major new product category emerged in 2009: the electronic compass for GPS-equipped handsets. Many new GPS enabled smartphones feature 3-axis silicon magnetometers in electronic compasses. Examples include the Apple iPhone 3GS, Nokia N97 and new N900, and recent Motorola Droid and Google Nexus 1 phones, to name a few.

This represents a significant magnetic sensor market driver in the coming years, especially as the performance demands drive high prices toward the same cost structure as high-end automotive sensors today. Interest in this market is of course high and new players like STMicroelectronics have recently jumped in through a partnership with Honeywell.

The pedestrian application requires heading measurement resolution of around 5°/s or lower, which is fine for Hall sensors (e.g. from market leader Asahi Kasei Microsystems today) but also down to 1°/s or better for LBS services using pointing devices. This has allowed companies supplying high performance AMR devices like Sensitec (supplies AMR die to MEMSIC) to enter the market in volume in 2009 to help serve these applications.

Figure 4. An electronic compass aids an augmented reality program to display information about scenes viewed through the mobile phone camera. (Courtesy LAYAR)

Industrial and medical applications

The industrial market is smaller (in units) than those for consumer, white goods, or automotive, but the components can command much higher prices — from several dollars up to $10 depending on resolution. This allows technologies like Reed, Hall, and also higher-performance AMR and GMR sensors to play. Often one AMR sensor can replace three Halls in a motor.

Major applications include industrial encoders and HVAC valve position sensing. Encoders convert rotary motion or position to a series of electronic pulses in a great variety of applications like computer numerically controlled (CNC) machines, robotics position and factory automation.

There are numerous brushless DC motors, and while not all require magnetic sensors to measure position of the rotor (as in this case there is only constant speed operation and no load changes), many use sensors where changing loads need to be monitored and managed.

Figure 5. Endoscopic capsule that can be swallowed. (Courtesy Given Imaging)

Medical applications are highly varied but include defibrillators and pacemakers, hearing aids, prosthetic joints, smart pills, e.g. capsule endoscope, diagnostic or drug delivery fluid flow monitoring, syringe pumps (position or level) and general automation of lab equipment (e.g. electronic pipettes) to name just a few. Prices are again higher than the mass-market applications.

Supply chain

The vast majority of unit shipments of magnetic sensors are for low-cost switches used in consumer electronics and appliances, PCs and notebooks — areas dominated by companies like AKM and Allegro.

Asahi Kasei Microsystems in 2009 stole the top spot in magnetic sensor revenues from Allegro Microsystems thanks to its leadership in the fast-growing electronic compass market. AKM is also the largest supplier in the world of Hall elements, e.g. for PC fans and all kinds of small motors used for example in DVD spindles, although the company begins to move upstream by adding addition electronics to make Hall ICs for more advanced monitoring in motors. It has a very diverse product portfolio, with only a small proportion for automotive, which helped it safely navigate the recent downturn. Likewise, Allegro splits its sales between automotive and consumer commodity markets.

Other major magnetic sensor players include Micronas, Infineon, NXP, and Melexis, as well as emerging companies like MEMSIC, Sensitec, and austriamicrosystems. The first four companies have strong automotive focus, although Melexis also serves some cell phone suppliers with switches, for example. The latter three have more diverse portfolios — e.g., Sensitec is a die supplier and partners to supply automotive applications such as wheel speed and mobile phone compasses. Unlike the MEMS market, there is little foundry offering (X-Fab and Advanced Microsensors are prominent) and cooperation often takes place among the component suppliers.

Conclusion

Silicon sensors are outgunning competition from potentiometers, Reed switches and micro-switches by eliminating issues with wear, by incorporating electronics on-chip for more intelligence per area, on robustness, and on cost and size. Hall Effect sensors ICs and switches largely dominate the silicon magnetic sensor IC market, but increasingly, AMR and also GMR sensors are used for high-performance applications. Added to this, new applications opening up and the market perspectives for magnetic sensors look very attractive bright in future.

For more information, see iSuppli’s special report from 2H09: "Magnetic sensors heading for big times."

Richard Dixon received his doctorate in semiconductor characterization from Surrey University and degree in materials science from North Kent University, and is senior analyst for MEMS at iSuppli, Spiegelstr. 2, 81241 Munich Germany; ph +49-89-207-026-070, e-mail [email protected].