How EM Microelectronic's Energy Harvesting ICs Enable Battery-Free IoT Devices

Introduction – Why Energy Harvesting Matters for IoT Engineers

The proliferation of IoT devices has created a maintenance nightmare for engineers designing connected systems. Battery replacement in remote sensors, industrial monitoring equipment, and wearable devices represents both a significant operational cost and environmental burden. EM Microelectronic's latest energy harvesting solutions directly address this challenge by converting ambient energy sources into

reliable, continuous power.

The company's approach centres on three core energy sources: solar photovoltaic cells optimised for indoor lighting conditions, thermoelectric generators (TEGs) that exploit temperature differentials, and emerging technologies for vibration and AC harvesting. Their silicon solutions have already proven themselves in commercial applications from Tissot solar watches to Urbanista's solar-powered headphones.

Features Addressing Energy Autonomy Challenges

EM Microelectronic's energy harvesting portfolio tackles the fundamental engineering challenges of ambient energy conversion:

Ultra-Low Voltage Operation

• AT8900 thermal harvesting IC operates from 5mV input

• Proprietary boost converter architecture maximises efficiency under small temperature differentials

• Compatible with standard Coilcraft transformers for simplified design integration

Intelligent Power Management

• AT8502 features dual storage capabilities with automatic switching

• Integrated USB charging for hybrid power scenarios

• Wake-up timers and power gating to minimise system consumption during low-energy periods

Optimised Solar Performance

• Maximum Power Point Tracking (MPPT) algorithms specifically tuned for indoor lighting conditions

• Support for both single-cell and multi-cell solar configurations

• Fast start-up capability even with depleted energy storage

Complete Development Ecosystem

• Comprehensive evaluation boards (EMEVB8900, EMEVB8502) with four different configurations

• Energy budget simulation tools available on EM's website

• Application notes covering TEG selection and solar system optimisation

The AT8900's standout capability lies in its thermoelectric harvesting performance. Operating from temperature differentials as small as 1°C, it can power wireless sensor nodes using nothing more than the heat differential between a radiator valve and ambient air. This has enabled applications like connected heating controls that never require battery replacement.

Product Portfolio Snapshot

Part	Application	Key Features
EM8500	Solar (single cell)	PMIC, dual storage, ultra-low consumption
EM8502	Solar (multi-cell)	Software-based DC/DC, MPPT, hybrid light optimised
EM8504	DSSC harvesting	Designed for dye-sensitised single cell
EM8506	Compact solar	Ultra-low power, small coil support
EM6890	MCU with harvesting	Mid-high power range, true MPPT
EM8900	Thermal harvesting	Ultra-low voltage boost for TEGs

Industry Applications and Use Cases

Wearables

• Solar watches (e.g., Tissot T-Touch Connect).

• Solar headphones (Urbanista).

• Wearables benefit from EM’s fast cold-start and hybrid indoor light support.

Smart Home & Consumer

• Solar remote controls and toll tags show how everyday devices can avoid battery swaps.

• BLE advertising mode powered by thermal harvesting enables battery-free smart sensors.

Industrial & Automotive

• Thermal harvesting supports connected valves, condition monitors, and predictive maintenance nodes.

• EM PMICs integrate with BLE platforms to deliver wireless, battery-independent IoT nodes.

Conclusion – Enabling the Next Generation of Autonomous Devices

EM Microelectronic's energy harvesting solutions represent a significant step towards truly autonomous IoT systems. The AT8900's ability to extract useful power from minimal thermal gradients, combined with the AT8502's sophisticated solar power management, provides engineers with proven technologies to eliminate battery maintenance across a wide range of applications.

The technology has already demonstrated commercial viability in demanding consumer applications, from luxury Swiss watches to premium audio equipment. As the IoT ecosystem continues to expand, particularly in industrial monitoring and smart building applications, energy harvesting will transition from a premium feature to an essential capability.

For engineers evaluating energy harvesting for their next project, EM's comprehensive development ecosystem significantly reduces the typical barriers to adoption. The combination of proven silicon solutions, detailed simulation tools, and extensive application support makes it feasible to integrate energy harvesting into products where battery replacement would otherwise represent a significant operational challenge.

Ready to eliminate battery replacement from your IoT designs? Contact our technical team to discuss how EM Microelectronic's energy harvesting solutions can transform your next project into a truly autonomous system.

---

Technical FAQs

Q: What's the minimum temperature differential needed for the AT8900 to operate?

A: The AT8900 can begin harvesting energy from temperature differentials as low as 1°C, though practical applications typically see 3-5°C differences. Output power scales with the square of the temperature differential, so even modest thermal gradients can provide sufficient energy for low-duty-cycle wireless applications.

Q: How does the AT8502 handle varying solar conditions throughout the day?

A: The AT8502 incorporates intelligent Maximum Power Point Tracking that continuously optimises energy extraction as lighting conditions change. Its dual storage system maintains power availability during extended low-light periods, whilst the wake-up timer system ensures the device remains responsive even when energy storage is depleted.

Q: Can these ICs work together in a hybrid energy harvesting system

A: Absolutely. The AT8900 and AT8502 can be combined to create systems that harvest from both thermal and solar sources simultaneously. The switch control functionality allows automatic source selection based on availability, maximising energy capture across different environmental conditions.

Q: What solar cell technologies are compatible with EM's harvesting ICs?

A: The portfolio supports conventional silicon solar cells, dye-sensitised solar cells (DSSC) through the AT8504, and Exeger's Powerfoyle technology. Each IC variant is optimised for specific cell characteristics, ensuring maximum energy transfer efficiency.

Q: How do these solutions compare to competitors in terms of efficiency?

A: EM's benchmarking data shows their ICs maintain over 85% efficiency across a broader range of input power levels compared to competitive solutions. This is particularly evident in indoor solar applications where competing solutions often drop below 60% efficiency under low-light conditions.

Q: What development support is available for engineers evaluating these technologies?

A: EM provides comprehensive development platforms including evaluation boards, energy budget simulation software, and detailed application notes. The company also offers direct technical support for custom transformer design and system optimisation, particularly valuable for high-volume applications requiring bespoke energy harvesting solutions.

Q. How do EM PMICs achieve ultra-low start-up?

A. Devices like the EM8900 operate from <10 mV input, enabling energy capture from very small thermal gradients.

Q. Can EM controllers manage both supercaps and batteries?

A. Yes, most EM850x devices feature dual-storage paths with switch and LDO management.