Cortex-M3 microcontroller cuts energy consumption
By Robert Cravotta, Technical Editor -- EDN, October 29, 2009
Energy Micro’s new EFM32G Gecko microcontroller family sports an energy-efficient implementation of a 32-bit ARM Cortex-M3-microcontroller architecture. The family thus targets applications, such as meters, requiring extended battery life. The devices support five power modes with an operating-voltage range of 1.8 to 3.8V. Active-mode current consumption is as low as 180 μA/MHz at 3V when executing code from flash memory. Standby-current consumption is 900 nA at 3V with a real-time clock, a 32.768-kHz oscillator, power-on reset, brownout detection, and full RAM and CPU retention. Deep-sleep-mode current draw is 20 nA at 3V, and wake-up time from sleep mode is as fast as 2 μsec.
The 32-MHz microcontroller configurations include as much as 128 kbytes of on-chip flash and 16 kbytes of RAM. Low-power components include a 200-μA, eight-channel, 12-bit, 1M-sample/sec ADC; a 100-nA brownout detector; a 50-nA, 32-kHz real-time counter; a 100-nA-receive-mode, 9600-bps-capable UART; and a 50-nA watchdog timer with dedicated RC oscillator. The ADC supports single-ended or differential operation. The 12-bit, 500k-sample/sec DAC supports two single-ended channels or one differential channel. As many as two analog comparators are available with support for capacitive sensing with as many as eight inputs. As many as 90 GPIOs (general-purpose input/outputs) support a 20-mA drive strength. Hardware AES (Advanced Encryption Standard) with 128/256-bit encryption and decryption is available. The configurable LCD controller can drive an array of 4×40 segments.
The 22 EFM32G microcontrollers are currently available for sampling in QFN64 and BGA112 packages, and subsequent versions will also be available in QFN32 and QFP100 packages. The operating-temperature range for these devices is −40 to +85°C.The company plans production availability for February and March 2010. Prices for the 32-pin devices start at $1.55 (100,000).
