Harness Ambient Power with EM Microelectronic’s Energy Harvesting Solutions

Introduction – Capturing Ambient Power for Autonomous Electronics

Harvesting ambient energy, whether from light, heat or vibration, enables truly autonomous electronics by removing the need for battery replacements or mains power. EM Microelectronic’s silicon-based energy harvesting portfolio integrates high-efficiency front-end converters with power management functions such as storage switching, low-drop-out regulation and wake-up timers in a single package. This reduces component count, board area and design complexity, while delivering continuous operation from minimal input voltages .

System Architecture and Component Chain

A typical energy harvesting system comprises five stages:

1. Harvester

   • Photovoltaic cell, thermoelectric generator (TEG) or piezoelectric element

2. Front-End Converter

   • Boost or buck converter with maximum power point tracking (MPPT) or cold-start capability

3. Energy Storage

   • Thin-film battery or supercapacitor

4. Power Management

   • Integrated switch control, low-drop-out (LDO) regulator and wake-up timers

5. Load

   • Sensor node, microcontroller, radio module

EM’s solutions combine stages 2 and 4 to streamline design and maximise conversion efficiency.

Solar Energy Harvesting with EM8502

Parameter	EM8502 Specification
Input Voltage Range	0.3 V – 3 V (1–3 cells)
Maximum Conversion Efficiency	> 90 % at 1 V input, light load
Integrated Functions	DC-DC converter, dual storage switch, LDO, wake-up timers
Quiescent Current	< 1 µA in storage mode
Development Platform	Solar Development Platform: real-time voltage survey, plug-and-play

• Cold-Start and MPPT EM8502 initiates from as little as 300 mV and employs adaptive MPPT to maintain peak extraction under varying illumination.

• Integrated Storage Switching Dual outputs allow charging a buffer capacitor or thin-film battery while supplying the load.

• Wake-Up Timers Internal timers reduce average consumption by powering the load only on scheduled intervals.

Thermal Energy Harvesting with EM8900

Parameter	EM8900 Specification
Cold-Start Voltage	≥ 5 mV from TEG
Integrated Functions	Ultra-low-voltage boost converter, storage control, wake-up timer
Quiescent Current	< 200 nA in sleep mode
Matching Components	Coilcraft LPR6235 transformers for AC harvesters; TEGs with 30 K/W thermal resistivity

• TEG Impedance Matching For a typical TEG (Seebeck coefficient ~10 mV /K, internal resistance ~2 Ω), a ∆T of 30 K yields ~300 mV open-circuit. EM8900 cold-starts at 100 mV and matches internal resistance for optimum power transfer.

• AC and Vibration Harvesting Using planar transformers (1 : 20 to 1 : 100 ratios), EM8900 can also rectify and boost AC from piezoelectric or electromagnetic vibration sources.

Design Considerations and Best Practices for energy harvesting solutions

• Energy Budgeting Use the EM online simulator to model harvested energy versus load requirements before hardware prototyping .

• Storage Selection Supercapacitors offer high cycle life but higher self-discharge; thin-film batteries provide stable supply at the cost of limited cycle count.

• Leakage Management Minimise PCB leakage currents with high-resistance coatings and by placing sensitive nets away from moisture-prone areas.

• Wake-Up Scheduling Match wake-up timers to application events: e.g. 1 Hz for environmental sensing or longer intervals for infrequent status updates, reducing average load.

Development Tools and Workflows

• Solar Development Platform (EM850x) Real-time voltage and current monitoring, corner-case control, battery hot-plug detection and DC 5 V USB interface for lab use .

• TEG Development Platform System-level prototyping board with access to thermal budget model and on-board connectors for TEG or vibration harvesters.

• Online Energy Budget System Simulator Web-based tool to define harvester type, environment profile and load to predict energy balance over time.

Application Examples with Power Budgets

1. BLE Beacon

   • Sleep current: 1 µA

   • Transmission burst: 10 mA for 10 ms every 10 s

   • Average load ~1.01 µA

   • Solar cell at 200 lux yields ~10 µW (≈2 µA at 5 V) → surplus energy for long-term operation.

2. Thermal-Powered Valve Controller

   • ∆T ~15 K on pipeline → ~150 mV from TEG

   • EM8900 boosts and charges a 10 mF supercapacitor

   • Actuation event (20 mA for 50 ms) drawn from stored energy, with wake-up timer for periodic status update.

3. Wearable Health Monitor

   • Photovoltaic harvester on clothing illuminated by indoor lighting (~500 lux)

   • Thin-film battery handles sleep and burst-mode sensing; EM8502 manages seamless switching.

Choose EM Microelectronic for the ultimate energy harvesting solution

EM Microelectronic’s energy harvesting solutions deliver a compact, integrated approach to exploit solar, thermal and vibration sources. By combining cold-start converters, storage switching and low-power timers into single ICs, engineers can deploy battery-free sensor nodes, wearable devices and industrial monitors with minimal board real estate and accelerated time to market.

To explore sample hardware, access the online simulator or discuss custom integration, please contact Ineltek today.