Semitrex: Efficient Power Conversion

Startup adds granularity for plug-in devices.


Power conversion is becoming a very big deal in the IoT world, as companies seek to connect the analog/physical world with the digital processing world.

Enter Semitrex, a Laguna Beach, Calif.-based startup led by Michael Freeman—the same guy who won Emmy awards for a mobile technology video. His latest incarnation uses what it describes as cascading capacitors in a multi-chip module (MCM), which requires as little as 0.5 milliwatts of standby power.

Like many of the new power-efficient approaches, this one provides more granular control over power, while also minimizing the number of parts and total area. By using muxcapacitor converters—capacitors, algorithms, switches and gate technologies—the company can reduce a higher DC voltage to a smaller one, rather than relying on transformers to step down the standard 170 volts in the United States and 325 volts in Europe.

“The difference is that we can use a tiny conversion ratio rather than a transformer,” said Freeman. “We decrease the number of parts from 40 to 50 per charger down to 20. We also reduce vampire power, which is responsible for about 400 terawatts per year across 10 billion to 12 billion devices. It draws less than 10 milliwatts in standby. Most people are trying to hit 30 milliwatts with a 5 volt charger.”

Wake-up time he said is currently 10 nanoseconds, but the goal is 5 nanoseconds. The company uses two architectures for its technology. One allows gates to be shared between capacitors. The second is a more precise gate technology that opens the gate all the way for charging, but which can close it partially when not all of the energy that has been stored is needed.

Freeman sees a need for these kinds of chips inside of SoCs for TV monitors, appliances such as washing machines and dryers, and inside of data centers. “Data centers are one of the big target markets because of the cost of air conditioning and heat distribution. These sites can run magnitudes cooler because of higher efficiency power conversion.”

The company was formed in 2012, but has been in stealth mode until this month. It is funded by private equity, but Freeman declined to be more specific.

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