The answer to giving smart meters a backup power source? A low-power and bypass converter, says a Texas Instruments applications engineer in a recent blog posting.
US-based Chris Glaser commented that while small coin cell batteries are an easy choice for a backup power source, the electronics in a smart meter needs 3.3V to operate in case of a power interruption, but a coin cell battery only gives between 2V and 3V.
Mr Glaser said: "A boost converter is a viable solution, but this power converter draws some operating current, which reduces the battery life by consuming power. How do we solve this dilemma?"
Powering smart meter electronics
Glaser suggests that an ultra-low power boost and bypass converter is a good solution. He said: "When the meter is operating normally and the battery is not needed, the boost converter enters a bypass mode and consumes 15 nA (yes, that’s 15 nana-Amps or 0.015 micro-Amps).
He concludes: "In this mode, the electronics remain powered. When a power failure occurs, a micro-controller turns on the boost converter to power the electronics effectively.
"Since the meter operates normally with power for most of its life, the coin cell battery can last 10 years or more."