The AEM20940 on a PCB. Image from e-peas
This PMIC is designed to help engineers take advantage of an often ignored source of energy that might well be available at the site of an IoT node. That untapped potential source is heat, which is converted to electricity through a process called thermoelectric generation.
How Does Thermoelectric Generation Work?
A temperature gradient is present when one side of an appropriate surface is hotter than the other side is. Heat will flow from the hotter side to the cooler side, causing movement of charge carriers. This creates a voltage difference between the two edges, and it can generate a not-insignificant amount of electrical power.
Image from e-peas
The left side of the above diagram illustrates the TEG that is the electrical power source. The center of the diagram is the e-pease IC that controls the disbursement of that power.
Advantages Conferred via the AEM20940
One of the main benefits of the IoT is the ability to monitor conditions at points that are difficult to access or even dangerous to the personnel that would otherwise be tasked to the job. But, those benefits are compromised if it is necessary to periodically enter those areas to change batteries.
A thermoelectric generator controlled by the e-pease AEM20940 can eliminate the need to change batteries at remote, inaccessible and potentially dangerous IoT node sites.
Diagram of the AEM20940. Image from the datasheet.
Geoffroy Gosset, co-founder and CEO of e-peas goes one step further when he explains that “it means that our clients will be able to design IoT systems that can efficiently extract energy from their surrounding environment whatever the available sources.”
AEM20940 Specs and Evaluation Board
The AEM20940 is available in 5 mm by 5 mm 28-pin QFN package. It is capable of extracting power from sources generating up to 110 mA. It will supervise the storage of electricity into easily chosen external rechargeable elements. It will also simultaneously supply energy to the system via two different regulated voltages:
- 1.2/1.8V, used for driving the system's microcontroller
- 2.5/3.3V, used for the RF transceiver
The eval board for the AEM20940. Image from e-peas via Publitek
It will only require external power during cold startup, either:
- 100 mV input voltage and 80μW input power with the optional external module (typical)
- 380 mV and 3μW input power without the optional external module (typical)
A detailed product sheet for the AEM20940 can be found here.
Other Thermal Energy and Energy Harvesting PMICs on the Market
- Analog Devices offers a range of chips to manage energy harvesting from thermoelectric, solar and other sources as detailed here. One example is the LTC3109 for TEG.
- STMicroelectronics offers the SPV1050, which also works with sources such as TEGs. It offers output voltages in the 1.8V and 3.3V ranges, as well as an unregulated output
- Maxim Integrated offers the MAZ17710 for energy harvesting. It provides a regulated output selected from 3.3V, 2.3V, or 1.8V.
Have you ever worked on an application that required TEG? What specifications were most important to you in your component selection? Share your experiences in the comments below.