Ambiq claims Arm Cortex-M4 power record

Ambiq Micro has topped EEMBC ultra-low power benchmark for microcontrollers, doubling the previous highest score (STMicroelectronics STM32L476RG). The Apollo MCU scored 377 on ULPBench.

BY Steven Bush, Electronics Weekly, Nov. 12, 2015 – 

The secret sauce is sub-threshold operation, where Ambiq appears to be succeeding where many others have failed.

"We have confirmed that the Apollo MCU scores were achieved in compliance with the ULPBench standard requirements. To state that the Apollo MCU's ULPBench results are impressive is an understatement, providing a practical demonstration of the device's nearly ideal logic gate voltage transfer characteristics and reduced gate input capacitance," said EEMBC president Markus Levy.

The benchmark simulates a typical low power design workload and measures the actual energy required to complete that workload."This approach normalises the many different behaviours of MCU operation such as active current, sleep current, wake-up time, core efficiency, and cache efficiency," according to Ambiq.

Apollo has a 24MHz Arm Cortex-M4 processor with floating point unit, up to 512kbyte flash and 64kbyte RAM. Peripherals include timing, I2C/SPI master and slave ports, and a UART.

Consumption is 34uA/MHz executing instructions from flash. Sleep is as low as 140nA.

Misfit has used the MCU in its Shine2 wearable fitness and sleep monitor.

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