MCU claims lowest current in every mode

"We are not cherry-picking a low-power spec, like the lowest sleep current or the lowest active-load current," said Shahram Tadayon, product marketing manager of MCUs at Silicon Labs. "We are claiming to consume the industry's lowest current in every mode."

Silicon Labs claims its F900 series controllers achieve the lowest available active-mode current consumption, at 160?A/MHz (up to 20MHz), which saves power when a system is running, and the lowest current in sleep mode—300nA with a real-time clock and just 10nA when using an external interrupt, both while maintaining full RAM retention. Those specs amount to more than a three-year battery lifetime—compared with a year and a half for the Silicon Labs family's nearest competitor—in apps where the controller awakens twice a second, takes a measurement with its integrated ADC, calculates a result and then goes back to sleep.

The F900's 12bit ADC has an autonomous power-saving burst mode that enables readings to be taken without awakening the CPU core. The series provides 25MIPS performance and up to 16Kbyte of flash memory for programs.

Tadayon said the microcontroller also has "an integrated DC/DC converter that lets you run on just a single AAA battery."

Normal batteries only put out 1.5 volts, requiring two for 3V electronics, even if very little current will be consumed. But the F900 series' on-chip DC/DC converter can transform any voltage to 3.3V, including that from a partially discharged AAA battery that supplied 1.5V when new but has dropped to as low as 0.9V. An external pin allows the microcontroller to provide up to 65mW from the 3.3V to power external components.

Silicon Labs targets the F900 family at smart meters, RFID tags, personal medical devices, sensor interfaces, energy harvesting, home security systems, and smoke and fire detectors. The company's EZRadio single-chip wireless transceiver can be added to configure the controller for wireless sensor nodes on weather stations, water and gas meters, and home automation and security systems.

- R. Colin Johnson
EE Times

For application notes on microcontroller click here.