Significance of primary side sensing to IoT

In November 2015, 196 nations have reached the Paris Agreement, regarding the reduction of climate change. The key goal: to limit global warming to less than 2°C compared to pre-industrialisation records. To meet this goal, there must be a net zero anthropogenic greenhouse gas emission during the second half of the 21st century. Under current energy usages, this is a tall order.

In fact, consumer demand is pushing the dial the other way. The so-called "Internet of Things" (IoT), is expected to connect an estimated 30 to 90 billion electronic devices by 2020. The IoT will be made up of a network of connected things such as sensors, monitors, measuring devices, computing devices, and wearables of all sorts (think small, integrated electronics). All of these "things" will require additional power. At present, the global electric grid would have to expand by 2 times with current power supply efficiencies in order to meet this demand. So, the question is how these billions of things will be powered efficiently enough that world governments can meet the Paris Agreement targets and put a hold on global warming.

Traditional power supply technology, popular for the last 20 years, uses flyback topology and secondary feedback control through opto-isolation, which has impeded the full deployment of the IoT. This technology contains too many components, which requires a large footprint – and each electronic part (discretes) presents its own drag on energy efficiency. Therefore, "parts reduction" is one key element to increasing the efficiency of things powered by the grid. In addition, the power supplies for IoT applications need to be able to fit into a small space and should be highly efficient.

Moreover, while power supplies used to be the last sub-system engineered, now an energy-efficient power supply is becoming a prerequisite for any electronic device coming into the market. IoT devices are no different. Consumers want to reduce their monthly energy bills, while governments and utilities want to limit the demand on the grid and its impact to global warming, with the additional burden of IoT devices. To accomplish this, a new approach is needed.

Tronium Primary Side Regulation (PSR) has been deeveloped with an eye on the power demands of the future. PSR helps reduce the part count in an under 50 W power supply from the typical 48 to 50 in a typical flyback configuration to less than 25.

Lower part count means not only a lower overall cost in end applications but an extreme reduction in size. For example, a typical 60-inch television has over 500 parts in it – 300 electronic parts and 200 mechanical. The size reduction benefits of the TRONIUM PSR solution promise to reduce part count by up to 90 per cent. This part reduction is of extreme importance for the sensors and small IoT devices that will be hooked up directly to the grid, especially since TRONIUM allows them to be connected, monitored or controlled either wired or wirelessly.

Three main goals
PSR technology achieves three main goals: runs at over 90-per cent efficiency at very low-medium-high load currents and provides almost zero load at a half a milliwatt of standby power. This, in turn, helps consolidate a fragmented industry by using fewer discrete parts – as currently it typically takes fourteen or more vendors to provide all of the parts to a power supply. Cutting the number of parts in half, partly by eliminating the opto-isolation parts, not only reduces the size of the footprint but also simplifies the inventory and design side of the process.

Let's take a closer look.

Out with the old...
As previously mentioned, the power supply solution commonly used in the industry today is flyback topology and secondary feedback through opto-isolation – typically with 9 to 11 parts that support optocouplers, which are electronic components that connect two separate electrical circuits by means of a light sensitive optical interface. An optocoupler includes an LED, which produces infra-red light and a corresponding semiconductor photo-sensitive device that detects and interprets the emitted infra-red beam. In this fashion, an electronic signal can come from the secondary side of the power supply circuit to the primary side of the circuit without breaching the transformer isolation barrier.