Gecko range of “energy-friendly” MCUs gains ARM Cortex-M0+ Core-based chips

October 10, 2013 // By Graham Prophet
Following its acquisition of Energy Micro, Silicon Labs has introduced the EFM32 Zero Gecko MCUs that provide low-energy operation, with 32-bit processing, at prices down to $0.49 in high volume.

Calling them the industry’s most energy-friendly 32-bit MCUs based on the ARM Cortex-M0+, Silabs says that EFM32 Zero Geckos are designed to achieve the lowest system energy consumption for a wide range of battery-powered applications such as mobile health and fitness products, smart watches, activity trackers, smart meters, security systems and wireless sensor nodes, as well as battery-less systems powered by harvested energy. The family includes 16 variants; as with previous Gecko chips, its designers say that lowest overall power usage comes from attention to each of active power, standby power and the power needed to wake the device ton active from any of its four sleep modes. Support continues to include an energy-profiling tool that will accurately predict battery life for a given application.

In deep-sleep mode, Zero Gecko MCUs have 0.9 μA standby current consumption with a 32.768 kHz RTC, RAM/CPU state retention, brown-out detector and power-on-reset circuitry active. Active-mode power consumption scales down to 110 µA/MHz at 24 MHz with real-world code (prime number search algorithm) executed from flash. Current consumption is less than 20 nA in shut-off mode. The EFM32 MCUs further reduce power consumption with a 2-microsecond wakeup time from standby mode.

Carried over from previous parts is the Peripheral Reflex System (PRS) that helps system-level energy efficiency; it monitors complex system-level events and allows different MCU peripherals to communicate directly with each other and autonomously without involving (waking) the CPU. Also continued from Tiny Gecko, Giant Gecko and Wonder Gecko devices are low-energy analogue peripherals include an analogue comparator, a supply voltage comparator, an on-chip temperature sensor and a 12-bit ADC with 350 μA current consumption at a 1 MHz sample rate. New is a programmable current digital-to-analog converter (IDAC), and Silabs says the EFM32 Zero Gecko devices are the only Cortex-M0+ MCUs with this facility on-chip. It generates a biasing current from 0.05-64 µA with only 10 nA overhead. The IDAC provides an