LTC3440EMS#TRPBF is a high-efficiency, micropower, synchronous step-up (boost) DC/DC converter designed and manufactured by Analog Devices Inc. (ADI) — formerly Linear Technology (acquired in 2017). It belongs to the ultra-low-power LTC34xx family, engineered specifically for energy-harvesting, battery-powered, and space-constrained portable applications, where delivering regulated output voltage from deeply discharged or low-voltage sources (e.g., single-cell Li-ion, NiMH, alkaline, or harvested ambient energy) with minimal quiescent current and high light-load efficiency is essential.
The “EMS” suffix denotes the 10-lead MSOP package (3 mm × 3 mm) — a compact, surface-mount, thermally enhanced, and widely manufacturable package; the “#TRPBF” indicates tape-and-reel packaging (2,500 units per reel), lead-free (Pb-free), RoHS-compliant, and halogen-free, qualified for industrial temperature range (–40°C to +85°C ambient).
⚠️ Critical Clarification:
The LTC3440 is not a standard boost controller or discrete solution. It is a fully integrated, synchronous, micropower boost regulator, featuring:
- Ultra-low quiescent current: Only 14 µA typical (at no load) — enabling multi-year operation on small batteries or trickle-charged supercapacitors (e.g., >10 years on a CR2032 with duty-cycled load);
- High efficiency across wide load range: >90% peak efficiency, and >85% efficiency even at 100 µA load, thanks to synchronous rectification (no external Schottky diode needed) and Burst Mode® operation;
- Wide input voltage range: 0.6 V to 5.5 V, supporting direct regulation from a single NiMH cell (～0.9 V min), single alkaline (～0.8 V), or energy harvesters (e.g., thermoelectric generators, piezoelectric transducers);
- Adjustable output voltage: 1.6 V to 5.25 V, set via external feedback resistor divider — ideal for powering 3.3 V microcontrollers (e.g., ARM Cortex-M0+, ESP32 deep-sleep peripherals) or 5 V sensors from sub-1 V sources;
- Integrated power switches: 1.5 A internal N-channel MOSFET switch + synchronous P-channel rectifier — eliminating external diodes and reducing board area, cost, and EMI.
It operates without external compensation — requiring only input/output capacitors, an inductor, and two feedback resistors — making it one of the simplest, most reliable, and lowest-power boost solutions available.
Introduction
The LTC3440EMS#TRPBF delivers enterprise-grade energy autonomy in the smallest possible footprint:
🔹 True sub-1 V start-up and operation: Can begin switching and regulate output from as low as 0.6 V input, enabling use with exhausted batteries or weak ambient energy sources — unmatched by most competitors (e.g., TPS61200: 0.3 V start, but 1.8 V min operating; MAX1722: 0.7 V start, but lower efficiency below 1 V);
🔹 Micropower intelligence: Burst Mode® operation maintains high efficiency down to 10 µA loads, while automatically transitioning to pulse-skipping or fixed-frequency mode above ～1 mA — no firmware control required;
🔹 Zero-compromise reliability: Pre-tested across HTOL (1000+ hours @ 125°C), with FIT rate < 16 failures per billion hours, and qualification per JEDEC JESD22-A108 and MIL-STD-883 — suitable for 15+ year infrastructure deployments;
🔹 Plug-and-play simplicity: No external diode, no compensation network, no enable logic needed — just VIN, VOUT, L, CIN, COUT, and RFB — accelerates prototyping and reduces BOM risk.
Its 10-lead MSOP (EMS) package (3 mm × 3 mm) offers best-in-class power density for micropower boost converters — supporting placement directly adjacent to battery connectors and energy harvesters on ultra-compact PCBs.
Key Features
✅ Micropower Boost Regulation:
• Input voltage range: 0.6 V to 5.5 V;
• Output voltage range: 1.6 V to 5.25 V, adjustable via external resistor divider (RFB1/RFB2);
• Output current: Up to 150 mA @ VOUT = 3.3 V, VIN = 1.2 V, scalable with inductor and layout;
• Quiescent current: 14 µA (typ.), 25 µA (max) — includes all internal circuitry.
✅ High Efficiency & Adaptive Operation:
• Peak efficiency: >90% @ VIN = 1.5 V, VOUT = 3.3 V, IOUT = 10 mA;
• Light-load efficiency: >85% @ 100 µA load, >75% @ 10 µA;
• Operating modes: Burst Mode® (for <1 mA), pulse-skipping (1–10 mA), and fixed-frequency (≥10 mA) — fully automatic.
✅ Integrated Power Stage & Protection:
• Internal switches: 1.5 A N-channel main switch + synchronous P-channel rectifier;
• Built-in soft-start: Prevents inrush current and output overshoot;
• Thermal shutdown: Activates at ～150°C, auto-recovery;
• Current limit: Cycle-by-cycle peak current limiting (～1.5 A).
✅ Low-Power Operation & Robustness:
• Shutdown current: < 1 µA (typ.), with fast wake-up (< 10 µs);
• ESD rating: > 2 kV HBM on all pins;
• Junction temperature range: –40°C to +125°C;
• No external compensation or diode required.
✅ MSOP-10 (EMS) Package & Industrial Qualification:
• 10-Lead MSOP (3 mm × 3 mm);
• RoHS-compliant, Pb-free, halogen-free;
• JEDEC J-STD-020 moisture sensitivity level (MSL) 1 — unlimited floor life.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (ADI) |
| Product Series |
LTC34xx Family (Micropower Synchronous Boost) |
| Model |
LTC3440EMS#TRPBF |
| Function |
Synchronous Step-Up (Boost) DC/DC Converter |
| Input Voltage Range |
0.6 V to 5.5 V |
| Output Voltage Range |
1.6 V to 5.25 V (adjustable) |
| Max Output Current |
150 mA (typ., VIN = 1.2 V, VOUT = 3.3 V) |
| Quiescent Current |
14 µA (typ.), 25 µA (max) |
| Shutdown Current |
< 1 µA (typ.) |
| Peak Efficiency |
> 90% |
| Light-Load Efficiency |
> 85% @ 100 µA |
| Switching Frequency |
1.2 MHz (fixed) |
| Internal Switches |
1.5 A N-MOS + Sync P-MOS |
| Package |
10-Lead MSOP (3 mm × 3 mm) (EMS) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Operating Temp. Range |
–40°C to +85°C ambient |
Typical Applications
🔹 Energy Harvesting Systems: Thermoelectric (TEG), piezoelectric (PZT), and photovoltaic (indoor PV) harvesters — using ultra-low 0.6 V start-up and Burst Mode® to extract usable power from µW-level inputs.
🔹 Battery-Powered IoT Sensors: Remote environmental monitors (temperature/humidity/air quality), agricultural soil sensors, and smart city nodes — leveraging 14 µA IQ and >10-year standby on coin cells.
🔹 Portable Medical Devices: Handheld diagnostic tools, wearable glucose/oxygen monitors, and disposable patch sensors — enabled by low voltage operation and high light-load efficiency.
🔹 Wireless Sensor Networks (WSNs): Zigbee, Bluetooth LE, and LoRaWAN end-nodes — where long battery life and compatibility with aging batteries are critical.
🔹 Backup Power & Supercap Management: Charging and regulating supercapacitors from weak sources (e.g., solar trickle charge), then powering real-time clocks (RTCs) or SRAM during main power loss.
🔹 Industrial Maintenance Sensors: Vibration, acoustic emission, and corrosion monitoring nodes — deployed in hard-to-access locations where battery replacement is impractical.
Development & Design Notes
🔧 PCB Layout Best Practices:
- Place input capacitor (4.7 µF ceramic) within 2 mm of VIN and GND pins — minimizes high-frequency loop inductance and improves EMI.
- Keep SW node short and wide — avoid vias or sharp corners to reduce ringing and radiated emissions.
- Route feedback resistors away from noisy traces (SW, GND return paths) — use Kelvin connection for bottom feedback resistor if precision is critical.
🔧 Component Selection & Configuration:
- Inductor: 4.7 µH, 0.5 A saturation current (e.g., Coilcraft MSS5131), shielded type preferred.
- Input cap: 4.7 µF X5R ceramic (0805) — low ESR critical for stability.
- Output cap: 10 µF X5R ceramic (0805) — ensure ≥ 2× the minimum recommended for ripple suppression.
- Feedback resistors: Use 1% metal-film types; e.g., for 3.3 V out: RFB1 = 301 kΩ, RFB2 = 100 kΩ → VOUT = 1.22 V × (1 + RFB1/RFB2) ≈ 3.30 V.
🔧 Thermal Management & Reliability:
- MSOP-10 has θJA ≈ 130°C/W (standard 2-layer board). For >50 mA continuous output, add ≥ 50 mm² copper pour under IC + ≥ 8 thermal vias — reduces θJA to ～65°C/W.
- FIT rate = 15.3 failures per billion hours, with FMEDA report supporting IEC 61508 SIL-2 — combine periodic health check (e.g., VOUT monitor every hour) for functional safety.
🔧 Efficiency & Start-Up Optimization:
- For lowest start-up voltage: minimize trace resistance between battery and VIN, and use low-ESR input cap — enables reliable start from ≤0.7 V.
- To maximize light-load efficiency: select inductor with low DCR (< 150 mΩ) and use X5R/X7R ceramics (avoid Y5V/Z5U due to bias effects).
- Avoid placing large copper planes under SW node — prevents coupling into sensitive analog sections.
🔧 System-Level Integration Tips:
- Pair with an energy-harvesting PMIC (e.g., LTC3588-1) upstream — LTC3440 handles final regulation for ultra-stable system rail.
- In multi-rail systems: use separate LTC3440s for each low-power rail (e.g., MCU core, sensor, radio) — avoids cross-regulation and enables independent power gating.
