MCU Provides 10x Energy Improvement with Subthreshold Tech

Each year, microcontroller (MCU) companies announce upgrades or additions to new and improved MCU families

However, one company’s recent announcement is producing more excitement and discussion than normal.

Ambiq Micro, a company that produces ultra-low power integrated circuits, just revealed a family of four 32-bit ARM Cortex-M4F microcontrollers that typically consume 5 to 10 times less energy than MCUs with similar performances.

According to Mike Salas, vice president of marketing at Ambiq Micro, the more electronics pervade the lives of people worldwide, the more important battery life becomes. “Consumers don’t want to recharge their wearables after less than a day of using them. Anything that has a battery is what we’re looking to improve upon.”

The company claims that wearable devices that might otherwise run for days or weeks on a battery can be redesigned to function for months or years with their new MCUs.

Ambiq Micro’s new Apollo family of microcontrollers is based on subthreshold technology – a technology that has been around for 30 years; however, Ambiq is the first company to bring it to the MCU realm.

The company’s Subthreshold Power Optimized Technology (SPOT) allows their new line of Apollo MCUs to run at 0.5 V, compared to the 1.8 V that other leading MCUs use. Essentially, the energy consumed is directly proportional to the square of the voltage used.

In 2005, Ambiq first evaluated subthreshold technology. The company wanted to achieve low-power and apply it on a wide-spread scale across an entire chip – across millions of transistors. It took several years, but by 2010, they finally found the formula. Ambiq’s SPOT-based real-time clock (RTC) device is already on the market, with millions of units sold.

The Apollo MCUs are low power, both in active and sleep modes. The active consumption of the devices is 30 µA/MHz, while the sleep mode consumption is 100 nA.

In addition, the Apollo MCUs operate at up to 24 MHz and are available with up to 512 kB of flash and 64 kB of RAM to accommodate radio and sensor overhead, as well as application code.

Ambiq Micro claims their new family of MCUs will benefit consumers in three different ways. “First, our technology can be used to extend the battery life of an existing product,” explains Salas. “The second thing we could enable is allowing manufacturers to reclaim the power budget and free up room for more features and functions. The third thing we enable is the possibility of reducing the size of a battery or eliminating batteries in general.”

The company is currently testing samples with key consumers and will begin production in spring of this year. “In the future, we’re going to continue to drive power down,” says Salas. “We’re going to try to cut power in half every two years, which is going to be a pretty big goal, but we think we can do it.