Silicon Labs applies “energy-friendly” approach to USB MCUs

May 14, 2015 // By Graham Prophet
Silicon Labs has configured the “Happy Gecko” microcontroller family to simplify USB connectivity for power-sensitive, battery-operated IoT applications.

Positioning them as the most energy-friendly USB-enabled microcontrollers, Silicon Labs’ EFM32 32-bit MCU Happy Gecko MCUs are designed to deliver the lowest USB power drain, enabling longer battery life and energy harvesting applications. Based on the ARM Cortex-M0+ core and low-energy peripherals, the Happy Gecko family offers USB connectivity for a range of IoT applications including smart metering, home and building automation, alarm and security systems, smart accessories and wearable devices.

USB is, the company says, the fastest growing interface for consumer applications and is also gaining significant traction in industrial automation, “In today’s IoT world, developers have discovered that adding USB interfaces to portable, battery-powered connected devices can double the application current consumption. Silicon Labs’ Happy Gecko MCUs provide an ideal energy-friendly USB connectivity solution for these power-sensitive IoT applications.”

Happy Gecko USB MCUs have an energy management system with five energy modes enabling applications to remain in an energy-optimal state by spending as little time as possible in active mode. In deep-sleep mode, Happy Gecko MCUs use 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 drops down to 130 µA/MHz at 24 MHz with real-world code (prime number algorithm). The USB MCUs further reduce power consumption with a 2-microsecond wakeup time from standby mode.

Happy Gecko family includes the Peripheral Reflex System (PRS) feature, which greatly enhances overall energy efficiency. The six-channel PRS monitors complex system-level events and allows different MCU peripherals to communicate autonomously with each other without CPU intervention. The PRS watches for specific events to occur before waking the CPU, thereby keeping the Cortex-M0+ core in an energy-saving standby mode as long as possible.

Happy Gecko MCUs feature many of the same low-energy precision analogue peripherals included in other family devices. These low-energy peripherals include an analogue comparator, supply voltage comparator, on-chip temperature sensor, programmable current digital-to-analogue converter (IDAC), and a