The key features that make one-time programmable memories ideal for a range of IoT devices.
By 2020 more than 50 billion devices will be connected to the Internet, according to Cisco’s latest forecast. Smartphone traffic will exceed PC traffic and broadband speeds will nearly double by 2021. And by the next Winter Olympics (Beijing 2022), 1 trillion networked sensors could be embedded in the world around us. While tech experts offer slightly different projections of actual numbers, it’s clear that the Internet of Things (IoT) will grow exponentially. And this explosion means new opportunities for one-time programmable (OTP) non-volatile memory (NVM).
With billions of sensors and processors gathering and analyzing massive amounts of information, there is a mounting need for embedded memories to store yottabytes and, soon enough, brontobytes of data. Traditionally NVM has been used for secondary/mass storage. But it’s getting faster and the cost per byte is going down, making NVM an option for primary storage as well.
OTP memory is used increasingly in networking and data-security applications such as code storage, encryption keys, analog trimming, RFID tags, and integrated circuit configuration. The use cases span the entire IoT ecosystem, from medical and industrial to financial and automotive markets.
To help us keep pace with the IoT explosion, memory experts have outlined some key requirements of devices using OTP NVM:
Secure data storage
With increasing hardware/software interdependencies and personalization features, efforts are redoubling to ensure the highest code security, key security, and data security across everything from automotive infotainment systems to medical wearables to mobile finance apps on our smartphones. The memory inside these IoT devices must also have the highest level of physical security.
Since NVM doesn’t depend on charge storage, once programmed it can’t be un-programmed by environmental or electrical upsets. Certain kinds of OTP (like anti-fuse one-transistor) are inherently secure against reverse-engineering approaches and offer tamper detection. Since programming does not visually change a bit cell, it’s almost impossible to detect bit-cell states. This makes one-transistor-OTP ideal for safe storage of encryption keys for secure wireless communication.
For automotive applications, where safety is paramount, OTP NVM provides the highest level of resistance from side-channel attacks and physical attacks. It’s already used as the storage mechanism in set-top boxes for securing the keys to broadcast content. Beyond security keys, OTP NVM is an excellent fit to store configuration parameters and settings for the engine control unit and the sensors it controls.
Minimize cost and area
For mass market appeal, personal IoT devices need to be smaller and more power-efficient, and they need to have a reasonable price point. This puts pressure on electronics companies to shrink the silicon footprint and minimize manufacturing costs without sacrificing performance.
OTP NVM is relatively low in cost because it’s easier to manufacture―it doesn’t require the additional masks or process steps of, for example, a Flash-based storage solution. OTP NVM can also track historical data streams more cheaply, making it perfect for IoT sensors, infrastructure tracking, and wearables. Certain types of OTP NVM―like one-transistor―are especially area-efficient.
An electronic device or embedded system is considered field programmable when its firmware (stored in NVM) can be modified without having to dismantle the device or return it to the manufacturer. This reduces cost and turnaround time for replacement of buggy or obsolete firmware.
Field programmability is especially useful for RFID tags, implantable medical devices, HDMI, and other consumer and automotive electronics products.
Minimize start-up time
OTP NVM is fast enough and consumes low enough power that code doesn’t need to be copied from external memory into on-chip SRAM. It offers the advantage that code can be executed in-place, quickly.
Low voltage, low power
Many IoT devices run on small batteries. In remote locations, replacing or recharging a battery may be difficult or even impossible. The sensor, processor, and any embedded memory should have low standby and operating power dissipation.
Certain kinds of OTP NVM consume 10x less active power and 40x less standby power. In particular, one-transistor-OTP memory uses a low read voltage, which further keeps the power usage down, making it ideal for battery-backed remote devices.
Nearly every IoT device can use some amount of OTP NVM. Power-sensitive designs—synonymous with nearly all designs in the IoT era—have a need for OTP memories. High-security apps benefit from OTP NVM because it’s extremely difficult to extract programmed data via visual inspection or power analysis.
As the numbers of connected devices scale up, OTP NVM is ready to handle the IoT explosion and bring about cost, size, performance, and security benefits with it.