STMicroelectronics EFL700A39-RL

Overview

EFL700A39-RL from STMicroelectronics is a solid-state rechargeable lithium thin-film microbattery with 0.7 mAh nominal capacity, 3.9 V nominal voltage, and 25.7 × 25.7 mm footprint. It features LiCoO₂ cathode, LiPON ceramic electrolyte, and lithium anode, enabling ultra-thin (220 µm) form factor and fast recharge for energy-constrained IoT sensor nodes.

For engineers reviewing the EFL700A39-RL datasheet, EFL700A39-RL pinout, EFL700A39-RL application, or EFL700A39-RL equivalent, key selection criteria include pulsed discharge capability (10 mA/100 ms), low self-discharge (3%/year), cycle life to 80% capacity (4000 cycles), and compliance with IEC 62133 and UN 38.3 for safe integration in wearable and smart card systems.

Technical Context

The EFL700A39-RL operates within 3.0–4.2 V and delivers up to 10 mA pulsed discharge at 30 °C with 2 V cutoff, while continuous discharge is limited to 5 mA. Its 100 Ω typical internal resistance supports stable voltage delivery under light-load conditions typical of RF ID tags and energy-harvesting storage.

Designed for ambient temperature operation (−20 to +60 °C), it maintains ≥80% capacity after 4000 cycles when cycled between 75% and 0% state of charge at 1C rate. Charge completes to 80% capacity in ≤20 minutes at 4.2 V constant voltage.

Key Specifications

Pinout & Package

Package: Surface-mount EnFilm™ thin-film battery with 25.7 × 25.7 mm footprint and 220 µm thickness; two-terminal construction with marked (+) and (−) interconnection pads on bottom side.

Key Features

Applications

Availability

EFL700A39-RL is available at Aetrix Electronics and suitable for IoT sensor nodes, smart cards, RFID tags, and wearable medical monitors requiring stable component supply with long-term lifecycle assurance.

Supply support for EFL700A39-RL 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, specializing in intelligent power, sensing, and microcontroller technologies for industrial, automotive, and consumer applications.

The EnFilm™ microbattery product line was developed to address ultra-thin, high-reliability energy storage needs in space-constrained wireless and portable electronics where conventional coin cells are mechanically incompatible.

FAQ

What is the recommended charging method for EFL700A39-RL?

Charge using a constant-voltage source set to 4.2 V ±0.05 V, with or without current limiting. Charging terminates naturally when current drops below 0.1 mA, delivering >90% of full capacity. Do not apply constant-current charging above 10 mA, as this exceeds pulsed discharge rating and risks cathode degradation per AN4085.

Can EFL700A39-RL be used in implantable medical devices?

No. ST explicitly prohibits use in implantable medical devices, including any device placed under the skin. The EFL700A39-RL is certified only for non-implantable medical applications such as external ECG patches or glucose monitors, and complies with ISO 7816 for smart card mechanical standards-not ISO 14708 for active implantables.

What is the maximum continuous discharge current?

The maximum continuous discharge current is 5 mA at 30 °C, as specified in Table 2. Exceeding this value causes accelerated capacity loss and thermal stress. For higher peak loads, use pulsed discharge mode (10 mA, 100 ms on/900 ms off) with cutoff at 2.0 V, validated in Figure 3 of the datasheet.

How does temperature affect cycle life?

Operating at 60 °C reduces cycle life significantly-ST specifies that cycling at elevated temperatures accelerates degradation. The rated 4000 cycles to 80% capacity assumes cycling at 30 °C. At −20 °C, discharge must be limited to 1/30 C rate (≈23 µA) to avoid lithium plating; full-rate discharge is only supported between 0 °C and 60 °C.