Energy Harvesting PMICs enable electronic systems to operate autonomously by converting solar, thermal, vibration, or RF energy into stable, usable electrical power. The core value is not only power conversion—it is energy continuity, ultra-low-power regulation, storage optimization, and reliability under intermittent input conditions.
This topic is a dedicated sub-page of the Power Management ICs (PMIC) Hub , and focuses exclusively on energy harvesting architectures, cold-start behavior, MPPT techniques, storage management, and 7-brand IC selection guidance for IoT, wearables, automotive sensors, and remote monitoring devices.
Navigation Context: This page is part of a structured PMIC ecosystem. Each sibling page focuses on a separate function (eFuse, Charger PMIC, Supervisors, Battery Protector). Together they form a complete knowledge system for low-power and energy-autonomous electronic designs.
Energy Harvesting PMIC — Intro & Standards
Energy harvesting PMICs cold-start from tiny inputs, track the best operating point (MPPT/IV-tracking), convert and regulate power, then charge storage (battery/supercap) or directly feed low-power loads. Typical use cases: wearables, remote sensors, asset trackers, and outdoor nodes.
Standards: EN 60529
Use IP65/67 for outdoor nodes to protect against dust and water ingress.
Standards: IEC 61800-9
Adopt energy-efficiency evaluation ideas at the system level; minimize idle Iq.
Key Metrics
Cold-start Vin, MPPT range, Iq, storage type, peak load buffering.
System Architecture
A complete path: Sources (PV/TEG/vibration) → PMIC modules (cold-start, MPPT, DC-DC, protections, policy) → Storage (battery/supercap) → Load (MCU/radio/sensors). Power lines are bold; control lines are dashed.
Choose MPPT Strategy
VOC-ratio (fast), P&O (robust), or power-estimate (sensor-light). Match to source dynamics.
Supercap Reality Check
Account for ESR, leakage, and balancing. Validate hot/cold to size burst buffers.
Peak Current Buffering
Use local caps and priority policy to cover radio TX peaks without brown-outs.
Energy Harvesting Sources
Compare photovoltaic, thermoelectric, and vibration sources by power density, dynamics, and impedance. Pick an MPPT/IV-tracking strategy that matches your source, then size storage for burst loads.
| Source | Typical Power | Dynamics | Impedance | Tracking | Best Use Cases |
|---|---|---|---|---|---|
| Photovoltaic | Indoor: ~10–200 µW/cm² Outdoor: ~1–10 mW/cm² | Slow-medium; shading/angle sensitive | Low-mid | VOC-ratio / P&O | Labels, sensors, outdoor nodes |
| Thermoelectric | ΔT 5–20 °C → tens to hundreds of µW | Medium; ΔT may reverse polarity | High | IV-tracking; flip detection | Pipes, boiler walls, engine bay edges |
| Vibration | µW–mW near resonance (0.1–1 g) | Pulsed; frequency-selective | High | Rectify + boost/charge-pump | Industrial machinery, bridges, motors |
Quick Estimator
E/day ≈ Pavg × 24 h; target storage = 2–3× daily need for cloudy/idle periods.
Risk Notes
Do 24h logging; seasonal derating; validate MPPT at temperature corners.
Design Tip
Match source voltage window to PMIC cold-start/MPPT range to avoid missed energy.
Power Conversion & Storage
From rectification and cold-start to DC-DC conversion and charging: build a power path that is efficient at light load, safe under temperature, and durable for the chosen storage (battery or supercapacitor).
Cold-start First
Confirm minimum Vin/startup power and time; ensure start succeeds at winter low-light.
Light-Load Efficiency
Prefer PFM/skip; gate-leak and Iq dominate at µW levels—measure below 50 µA load.
Charging Safety
Follow JEITA for Li-ion; supercaps need balancing and ESR/temperature checks.
Policy & Priority
Define good/brown-out thresholds and burst windows so RF peaks never brown-out MCU.
Load Regulation & Efficiency
Keep the output stable with robust voltage/current regulation and quantify losses across light, nominal, and peak loads. Track load regulation (%/A), η vs Iout, and thermal hotspots to define derating.
Load Regulation
Measure ΔV/ΔI across ±10/30/50% steps; target fast recovery with minimal overshoot.
Light-Load Focus
At µW–mW levels, Iq dominates. Prefer PFM/skip and minimize leakage paths.
Thermal Path
Use copper pours + via arrays; validate hotspot temps on coil, rectifier, and switch.
Derating Policy
Define temp thresholds with hysteresis; reduce power under poor alignment or high ΔT.
Communication & Integration
Connect the PMIC to the host via I²C/SPI and map status/alerts to your firmware policy. Design the hardware partition for low-noise signals and ensure level compatibility and proper pull-ups.
Bus & Levels
Confirm I²C pull-ups and voltage levels (1.8/3.3 V). SPI mode/freq within PMIC limits.
Events & Policy
Use interrupts for UVLO/OCP/thermal; gate non-critical loads until storage is ready.
Layout & Noise
Separate power and signal domains; route clocks away from the coil/inductor current.
Firmware Hygiene
Probe device ID, read OTP/defaults, log faults, add watchdog and brown-out recovery.
Layout & EMI Design
Minimize high-frequency power loops, preserve continuous return paths, and isolate noisy switching nodes from sensitive I/O. Use filtering, shielding, and sound grounding to keep emissions low and measurements clean.
HF Loop Area
Route rectifier→switch→inductor→cap tight; shrink SW copper and avoid long antennas.
Return Continuity
Keep solid reference ground; avoid crossing splits; provide via arrays under power paths.
Filtering & Snubbers
Add π/CMC at input, RC snubbers and gate resistors to tame ringing and dV/dt.
RF Coexistence
Separate RF/clock lines from SW; use shields/ferrites; add test pads for probes.
Validation & Testing
Validate cold-start, MPPT stability, efficiency, and charging behavior across source types (PV/TEG/vibration). Log power, temperature, and events; define pass/fail thresholds and a clean retest plan.
| Test Item | Method | Metric | Pass/Fail Guide |
|---|---|---|---|
| Cold-start | Low-light/low-ΔT start | Start time, Vin(min) | Start < X s at Y lux / ΔT |
| MPPT stability | Step light/frequency | Power tracking error | Within ±Z % over steps |
| Efficiency | µA→mA load sweep | η @ points | Meet curve spec ±Δ |
| Charging | CC/CV or balance | Temp, time, EOL | JEITA limits / ESR OK |
| Compatibility | PV/TEG/vibration | PG/UVLO events | No false trips |
Repeatability
Lock ambient, fixtures, and scripts; log firmware build and board rev.
Safety Margins
Set thresholds with hysteresis; validate hot/cold corners and aged storage.
Source Sweeps
Sweep lux/angle (PV), ΔT polarity (TEG), and freq/acc (vibration).
IC Selection (7 Brands)
Match source type, cold-start ability, MPPT strategy, and storage support. Choose telemetry (I²C/SPI) only when policy or logging needs it—otherwise favor lowest Iq.
Source Fit
Indoor PV → ultra-low Iq, VOC-ratio MPPT; TEG → flip-safe input; Vibration → rectifier + boost.
Storage Strategy
Li-ion needs CC/CV & JEITA; supercap needs balancing and ESR checks for bursts.
Telemetry or Not
Use I²C/SPI for logs/policy; otherwise prefer GPIO-only parts to save quiescent power.
| Brand | Family / Example | Power Class | Cold-start / MPPT | Storage Support | Interface | Notes / Use Cases |
|---|---|---|---|---|---|---|
| TI | BQ255xx / BQ256xx family | µW–mW | Ultra-low start • VOC-ratio / P&O | Li-ion • Supercap (balance ext.) | I²C / GPIO | Indoor PV tags, sensor beacons |
| ST | SPV / PMIC front-ends | µW–mW | Cold-start • MPPT assist | Li-ion • Supercap | I²C / GPIO | PV nodes, loggers, low-ΔT aid |
| Microchip | MCP EH/Charge mgr. | µW–mW | Low-start • IV-tracking | Li-ion • Supercap | GPIO / I²C | Simple policy, long shelf life |
| NXP | PMIC front-ends | mW (burst) | P&O / telemetry | Li-ion • Supercap | I²C / SPI | IoT gateways, richer logging |
| onsemi | Boost/ideal diode family | mW+ | Cold-start assist | Li-ion • Supercap | GPIO | Outdoor nodes, higher peaks |
| Melexis | Low-power sensor/EH front-end | µW | Ultra-low Iq focus | Supercap / Micro-bat | GPIO | Sensor tags, duty-cycled RF |
| Renesas | ISL / RAA power front-ends | µW–mW | MPPT options • robust prot. | Li-ion • Supercap | I²C / GPIO | Industrial telemetry, mixed sources |
FAQs
Short answers to common questions on efficiency, input needs, compatibility, and EMI suppression for energy harvesting PMIC designs.
Why is indoor efficiency lower than outdoor?
Indoor lux is orders lower; converter Iq and leakage dominate. Use VOC-ratio MPPT, minimize Iq, and size storage for long idle.
Cold-start fails at low light—what to do?
Verify minimum Vin and input power, pre-charge storage if allowed, and consider larger PV/TEG area or lower-loss rectifiers.
Which source fits my device?
Indoor PV for labels/tags, outdoor PV for higher duty, TEG for ΔT sites, vibration for machinery; match MPPT method to source dynamics.
How to size storage for burst radio loads?
Compute E=½CV² and ensure 2–3× the burst demand; add local caps near RF and define brown-out thresholds with hysteresis.
Can I mix battery and supercap?
Yes—battery for energy density, supercap for peak current; add balancing and ideal-diode OR-ing to prevent backflow.
What JEITA rules should I follow for Li-ion?
Respect temperature zones for CC/CV, taper current near full, and derate in hot/cold to protect lifetime.
I²C vs no-bus—how to choose?
I²C/SPI offers telemetry and policy control; no-bus saves Iq. If logging/remote updates matter, use I²C; otherwise GPIO-only.
UVLO/PG thresholds—any tips?
Calibrate to your storage and load peak needs. Add margin and hysteresis to avoid chatter in variable sources.
TEG polarity flips—how to handle?
Use input OR-ing or bridge, detect flips in firmware if available, and validate cold-start with small ΔT.
Vibration harvester doesn’t deliver enough energy.
Re-match frequency/acceleration, reduce rectifier loss, add charge-pump/boost, and log duty to adapt reporting.
EMI disturbs my wireless module.
Shorten SW loop, add π/CMC filters, keep RF away from high dV/dt nodes, and verify with near-field probe/SA scans.
What should I log for validation?
Vin/Pin, Vout/Iout, η, temperatures, MPPT mode, PG/FAULT events, and firmware build + board revision for traceability.
Energy Harvesting PMIC
Convert weak and fluctuating sources—light, heat, and vibration—into usable power: achieve fast cold start, maximize energy via MPPT/IV tracking, and ensure longevity through charging & protection, backed by system-level layout and validation for end-to-end reliability.
This page follows the chain “Source → PMIC → Storage → Load” and provides a practical guide—from architecture, layout, and EMI to validation and IC selection—plus downloadable resources.
Resources & RFQ
Download the test sheets and calculators, then verify cold start, MPPT, efficiency, and charging step by step. Submit your BOM to receive 48-hour selection advice.
EH Test Sheet (XLSX)
Covers cold start, MPPT, efficiency, charging phases, and alarm logging.
DownloadPower Ramp Log (PDF)
Logging sheets for power step/hold, thermal rise, and stability.
DownloadStorage Calculator (XLSX)
Supercap/battery capacity and ESR estimation, peak-current buffering calculations.
Download