STMicroelectronics EFL1K0AF39RL

Overview

EFL1K0AF39RL from STMicroelectronics is a solid-state thin-film rechargeable lithium microbattery with LiCoO₂ cathode, LiPON ceramic electrolyte, and lithium anode; nominal capacity 1 mAh, nominal voltage 3.9 V, internal resistance 80 Ω, operating voltage range 3.0–4.2 V, and thickness 160 µm; used for energy storage in ultra-low-power IoT sensor nodes and wearable health monitors.

For engineers reviewing the EFL1K0AF39RL datasheet, EFL1K0AF39RL pinout (two-terminal construction), EFL1K0AF39RL application in energy harvesting systems, or EFL1K0AF39RL equivalent for low-profile backup power, this page delivers verified electrical specs, mechanical constraints, embedded assembly guidance, and ST-validated charge/discharge protocols.

Technical Context

The EFL1K0AF39RL employs all-solid-state architecture with a LiPON (lithium phosphorus oxynitride) electrolyte enabling stable ion conduction without liquid leakage or thermal runaway risk. Its 160 µm thickness and 25.8 mm × 28.8 mm footprint support integration into space-constrained flexible PCBs and laminated smart cards.

It delivers 1 mAh capacity at 100 µA discharge (4.2 V → 3.0 V, 25 °C), supports 15 mA pulsed discharge (100 ms on/900 ms off), and retains ≥80% capacity after 4000 cycles at 25 °C under 1 C cycling between 75% and 0% SoC.

Key Specifications

Pinout & Package

EnFilm™ microbattery EFL1K0AF39RL uses a two-terminal surface-mount structure: anode and cathode pads located on opposite long edges of the rectangular 25.8 mm × 28.8 mm substrate. No leadframe or wirebonding - terminals are metallized Ni strips (F designation) for solder or conductive adhesive attachment. Thickness is fixed at 160 µm; no mechanical mounting holes or clips required.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thin-film microbattery applications.

Compared with Cymbet CC1002 and Infinite Power THINERGY® MEC225, EFL1K0AF39RL offers optimal balance of capacity (1 mAh), ultra-thinness (160 µm), and industrial-grade cycle life (4000 cycles), making it preferred for space-limited, multi-year IoT nodes where moderate pulse current and strict RoHS compliance are critical.

Availability

EFL1K0AF39RL is available at Aetrix Electronics and suitable for wireless sensor nodes, smart wearables, RFID smart tags, and energy harvesting modules requiring stable component supply, long-life embedded power, and RoHS-compliant thin-film battery technology.

Supply support for EFL1K0AF39RL 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, MEMS sensors, and power management solutions for industrial, automotive, and consumer markets.

The EnFilm™ microbattery product line targets ultra-low-power, space-constrained applications including IoT edge nodes, medical wearables, and smart packaging, where solid-state reliability and sub-0.2 mm form factor are non-negotiable design requirements.

FAQ

What is the maximum safe reflow temperature for EFL1K0AF39RL during PCB assembly?

The EFL1K0AF39RL must not exceed 100 °C during solder reflow. ST's TN1249 technical note specifies peak temperature ≤95 °C for ≤60 seconds using SnAgCu paste. Exceeding this degrades the LiPON electrolyte, increasing internal resistance and reducing cycle life. Conductive adhesive bonding is recommended for higher-temperature processes.

Can EFL1K0AF39RL be charged directly from a solar cell without a dedicated charger IC?

Yes - the battery accepts constant-voltage charging at 4.2 V ±0.05 V with or without current limiting. A properly sized solar cell delivering ≤4.25 V open-circuit and ≤15 mA short-circuit can charge it directly, provided a series Schottky diode prevents reverse leakage at night. For reliable long-term operation, a dedicated LDO-based charger (e.g., ST's SPV1040) is recommended to enforce voltage precision and thermal cutoff.

Is EFL1K0AF39RL qualified for use in implantable medical devices?

No. ST explicitly prohibits use in implantable medical devices (defined as devices placed under the skin), US government custom applications, and wafer test equipment. While approved for external healthcare wearables (e.g., pulse oximeters, activity trackers), it lacks biocompatibility certification and hermetic sealing required for implantation. Refer to Section 2 of the datasheet for full Prohibited Applications listing.

How does the 0% state-of-charge requirement affect embedded assembly?

ST mandates that EFL1K0AF39RL be assembled at 0% SoC to minimize internal resistance drift and capacity loss during lamination or pressure bonding. Charging before assembly induces electrochemical stress under heat/pressure, causing irreversible Li dendrite formation. The battery must be pre-discharged to ≤2.5 V using a 1 kΩ load prior to placement, then charged only after full mechanical integration and environmental stabilization.