Analog Devices Inc. LTC3108IGN#PBF

Overview

LTC3108IGN#PBF from Analog Devices is an ultralow-voltage step-up converter and power manager IC designed for energy harvesting from thermoelectric generators (TEGs), thermopiles, and micro-solar cells. It operates from input voltages as low as 20mV, delivers four selectable regulated main outputs (2.35V/3.3V/4.1V/5V), integrates a 2.2V/3mA LDO, and supports storage capacitor backup via VSTORE - enabling autonomous wireless sensor nodes in HVAC, industrial monitoring, and predictive maintenance systems.

For engineers reviewing the LTC3108IGN#PBF datasheet, LTC3108IGN#PBF pinout, LTC3108IGN#PBF application, or LTC3108IGN#PBF equivalent, this page provides verified technical context, exact pin functions per SSOP-16 package, confirmed start-up voltage (20mV), output sequencing behavior, PGOOD timing, and validated alternative options for energy-harvesting power management designs.

Technical Context

The LTC3108IGN#PBF uses a resonant step-up oscillator with external transformer (e.g., 1:100 turns ratio) to boost sub-50mV inputs; its internal rectifier and charge pump feed VAUX, which powers all circuitry and enables VOUT charging once >2.5V. Synchronous rectifiers activate above 2V to improve efficiency, and a precision micropower reference ensures stable output regulation across –40°C to 125°C.

VOUT is programmed via VS1/VS2 logic pins (GND/VAUX combinations), while VOUT2 is a host-controlled 1.3Ω P-channel switch (0.3A peak, 5µs turn-on) for pulsed sensor powering. PGOOD monitors VOUT within ±7.5% (rising) / –9% (falling) and drives an open-drain output with 1MΩ pull-up to VLDO.

Key Specifications

Pinout & Package

The LTC3108IGN#PBF is packaged in a 16-lead plastic SSOP (narrow) with exposed thermal pad not present (DFN variant has exposed pad; SSOP uses pins 1, 8, 9, 16 as GND).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultralow-voltage energy harvesting power management applications.

Compared with LTC3108IGN#PBF, the DFN variant offers superior thermal dissipation in dense layouts, while the LTC3108-1IGN#PBF removes VOUT programming flexibility to reduce routing complexity - both retain identical energy harvesting core architecture and 20mV start-up capability.

Availability

LTC3108IGN#PBF is available at Aetrix Electronics and suitable for remote wireless sensor nodes, HVAC system monitoring, and industrial predictive maintenance requiring stable component supply across extended temperature ranges (–40°C to 125°C).

Supply support for LTC3108IGN#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3108 product line was engineered specifically for autonomous, battery-free operation in ultra-low-power energy harvesting systems - targeting applications where input sources deliver <500mV and <1mA, such as TEGs, thermopiles, and micro-PV cells.

FAQ

What is the minimum input voltage required for LTC3108IGN#PBF to start switching?

The LTC3108IGN#PBF achieves reliable start-up at 20mV when used with a 1:100 transformer turns ratio and no load on VAUX. This specification is guaranteed over the full –40°C to 125°C operating junction temperature range. At lower ratios (e.g., 1:50), start-up voltage increases to ~50mV. The 20mV figure reflects worst-case conditions including cold temperature and maximum process variation.

How does the LTC3108IGN#PBF select its main output voltage (VOUT)?

The LTC3108IGN#PBF selects VOUT via two logic pins: VS1 (Pin 11) and VS2 (Pin 10). Each pin is tied either to GND or VAUX (not left floating) to program one of four fixed outputs: GND/GND = 2.35V, GND/VAUX = 3.3V, VAUX/GND = 4.1V, VAUX/VAUX = 5V. This eliminates external resistor dividers and associated board leakage errors that compromise accuracy at ultralow currents.

Can LTC3108IGN#PBF power a microcontroller directly, and if so, how?

Yes, the LTC3108IGN#PBF can power a microcontroller directly using its integrated 2.2V LDO (VLDO pin). The LDO delivers up to 3mA with ±3% regulation and starts operating as soon as VAUX reaches 2.3V - often before VOUT is fully charged. It requires a minimum 2.2µF ceramic capacitor from VLDO to GND for stability and is powered by the higher of VAUX or VOUT, ensuring continuous operation during VOUT transients.

What is the function of the VOUT2 output on LTC3108IGN#PBF, and how is it controlled?

VOUT2 on the LTC3108IGN#PBF is a host-controlled switched output connected to VOUT through a 1.3Ω P-channel MOSFET. It is enabled by driving VOUT2_EN (Pin 12) high (threshold ≈1V), and disabled by pulling it low or leaving it open (internal 5MΩ pull-down). With 5µs soft-start and 0.3A peak current limit, VOUT2 safely powers pulsed loads like RF transceivers or analog sensors without disturbing VOUT regulation.

Does LTC3108IGN#PBF support charging rechargeable batteries, and what are the limitations?

Yes, the LTC3108IGN#PBF supports trickle-charging NiCd or NiMH batteries via the VSTORE pin, which charges to VAUX's clamped voltage (5.25V typical) after VOUT regulation. However, VSTORE current is limited to ≤7.5mA, making it suitable only for low-rate charging - not for Li-ion or high-capacity batteries. For sustained high-current loads, the VOUT capacitor must supply pulse energy; VSTORE serves backup during input dropout.