Urgency Sensors Enable Reliability as a Service for EVs

If you’re an electronics professional old enough to remember watching new episodes of Mork and Mindy or Salvage 1 on TV, you’re probably familiar with the humble urgency sensing circuit (USC). It’s a component commonly found in copy machines, home appliances, and other electronic products of 1970s.

Surprisingly, that obscure and nearly forgotten electronic component is enjoying newfound popularity with automakers. USCs now are being used to solve an emerging problem with their EVs.

At its simplest, a USC consists of an op amp and a Murphy junction diode (see “It’s Not Just the Law: A Brief History of Urgency Sensing, below), which can detect a user’s levels of concern and anxiety, and produce an output voltage proportional to the criticality of the task being performed in their general proximity (Fig. 1).

One of the earliest, and most popular, applications for these circuits was generating field service calls for the large high-speed photocopiers that were essential equipment for nearly every office during that era. Rather than use a simple random number generator to trigger paper jams, toner leaks, and other faults, a USC would enable the copier to operate reliably most of the time. It would only require an expensive visit from a field service technician when the customer was eager to pay for the service.

Demand Downslide for USCs

Demand for USCs declined as photocopiers became smaller and inexpensive enough whereby most offices could have several machines, each being replaceable for less than the cost of an extended service contract. Appliance manufacturers continued to use them in washing machines and refrigerators for another decade or so, until the growing complexity of so-called “smart” washers and refrigerators introduced enough naturally occurring random failures to make the sensors unnecessary.

By the end of the1980s, demand for USCs dwindled to the point where nearly all semiconductor makers stopped manufacturing them, except for YoYo Dyne semiconductors. The company kept them in limited production at its Grovers Mill, N.J. facility for a handful of legacy customers.

On a sidenote, YoYo Dyne’s facilities were pressed into service during the early days of the COVID-19 pandemic when it was discovered that emissions from dark emitting diodes (DEDs), a variant of the USC, proved to be a highly effective way to kill the deadly Corona virus.

USCs Making a Comeback

Recently, however, interest in USCs has grown dramatically as automakers struggled to adjust to the challenging economics of the electric-vehicle market.

Several legacy manufacturers were caught by surprise when their new EVs required drastically lower levels of maintenance and repairs. While customers were attracted to the EV’s higher reliability and negligible maintenance costs, dealers suffered as the revenue streams traditionally generated by oil changes, tuneups, and other routine service work evaporated.

“The damned EVs are so much simpler that, besides replacing tires and the occasional brake job, the only time we see them in the shop these days is when they’ve gotten into an accident” said Brad Thayer, VP of customer service for Bavarian Mechanical Works’ (BMW), North American division.

Faced with rapidly dwindling profits, BMW and other legacy carmakers experimented with various ways of generating semi-random faults in their EV’s drivetrains, climate controls, and infotainment systems. After exploring several approaches, several leading companies, including BOTCH, a European automotive components manufacturer, concluded that USC-based fault generators would be a cost-effective and reliable technology for strategically moderating EV reliability.

USCs Become Programmable

As part of a strategic partnership, BOTCH and YoYo Dyne developed a line of programmable, single-chip USC devices that are less expensive and more compact and energy-efficient than their 70s-era predecessors. The sensors are also equipped with a CANbus interface, which allows their urgency threshold to be set by one of the vehicle’s ECUs or via remote over-the-air (OTA) software update (Fig. 2).

Thanks to variable thresholds, programmable USCs made it possible to offer different levels of reliability as part of the various trim and option packages they offer to their customers. Most EV makers have chosen to have their vehicles delivered to the dealer with a default “ICE-grade” reliability setting. This can be easily adjusted upwards, when the firmware that supports other optional features, such as autopilot, extended range, or advanced safety capabilities, are enabled.

“This gives our customers the option to spend a little more up front to unlock the full level of reliability the manufacturer’s vehicles can offer,” explained Janice Harrigton, a senior business strategy consultant at Boozy-Ellen Humbelton.

RaaS Subscriptions  

Some automakers have taken a different approach to marketing their premium reliability services by offering them on a subscription basis. BMW, for example, has announced plans to offer monthly subscriptions for three different levels of Reliability-as-a-Service (RaaS) for its 2027 EV products.

“The subscription model we offer for our heated seats proved to be so successful that extending it to this area of the BMW experience seemed like the logical next step,” said VP Thayer.

Beginning with the 2027 model year, the company’s EVs will be programmed to support full reliability for 12 months at no charge, with the option to continue the premium service or opt for lower levels of driving confidence.

“This win/win strategy allows us to deliver our company’s legendary quality in a cost-effective manner that’s tailored to our customer’s budget,” concluded Thayer. Several other EV makers are expected to adopt RaaS strategies for their EV products before the close of the 2026 model year.