Proving the Business Case for the Internet of Things

Toshiba microcontroller ups accuracy for smart meters

Steve Rogerson
March 16, 2015
To increase the precision of current and voltage measurements in smart meters, Tokyo-based Toshiba has introduced a microcontroller using the ARM Cortex-M3 core.
Sample shipments of the TMPM311CHDUG are scheduled for April with mass production due to start in September 2015.
A power measurement analogue front-end for single-phase and three-phase smart meters requires simultaneous high-precision current measurement, voltage measurement and power calculation. A four-channel 24bit delta-sigma type A-D converter incorporated in the product enables high-precision current measurement, voltage measurement and power calculation at the same time.
The A-D converter measures current and voltage simultaneously. The allowance for measurement error of single-phase power calculation is within 0.1%. Simultaneous current and voltage measurements for up to eight channels are supported by using two units of the microcontroller in an interlocking manner.
A built-in low-noise variable gain amplifier in each conversion channel of the A-D converter enables high-precision measurement for current from a current sensor. This supports both power calculation meters and various sensor equipment. There is also a built-in temperature sensor that enables temperature corrections.
In combination with the company’s TMPM411F20, which incorporates two Cortex-M4F cores and performs measurement and communication controls on one chip, and enables tamper detection in the power failure and interrupt detection for measurement and communications at low power consumption, this device can realise a smart meter system that integrates measurement and communications on a board.