Low power MCUs target wearable applications

The devices allow engineers to design or redesign wearable devices to operate for months or years rather than days or weeks. The expanded power budget also provides engineers with the opportunity to add features or use a smaller battery.

The Apollo MCUs, which optimise both active and sleep mode power, consume 30µA/MHz when executing instructions from flash and feature average sleep mode currents as low as 100nA. Due to the ARM Cortex-M4F core, this low energy consumption does not affect performance. The processor offers the computational power required in an IoT world, where algorithmic processing requirements are increasing due to the growing use of sensors, audio and automation sources.

Operating up to 24MHz, the devices are available with up to 512kB of flash and 64kB of RAM, accommodating radio and sensor overhead. I2C/SPI ports and a UART enable communication with sensors, radios and other peripherals, as well as an optional host processor. On-chip resources include a 10 bit, 13-channel, 1MS/s ADC and a temperature sensor with ±2ºC accuracy. The Apollo MCUs are available in two packaging options: a 64-pin, 4.5x4.5mm BGA package with 50 GPIO or a 2.4x2.77mm, 42-pin CSP with 27 GPIO.

Rather than using transistors that are turned all the way ‘on’ at 1.8V, Ambiq Micro’s SPOT platform operates transistors at subthreshold voltages of less than 0.5V. To compute in both digital and analogue domains, the platform uses the leakage current of ‘off’ transistors. The challenges of noise susceptibility, temperature sensitivity and process drift previously associated with subthreshold voltage switching, is addressed by the technology.

Mark Foley, CEO and President, Ambiq Micro, commented: “The energy efficiency of MCUs has been getting better over the last few years but nobody has delivered the near order-of-magnitude improvement made possible by our SPOT platform. The technology, proven in our real-time clocks over the last couple of years and now applied to Apollo MCUs, delivers the breakthrough in battery life that designers of portable devices have been demanding. Looking ahead, we predict that semiconductor energy consumption will be halved every two years. The trend starts here.”

The Apollo MCUs are sampling now and will be available in production quantities in spring 2015. The devices will be priced from $1.50 each and sold in 10,000 quantities.