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Epson PMIC Solutions: Powering Next-Generation Hearing Aids and Wearables

Updated: Mar 11

Introduction: The Challenge of Powering Miniaturised Devices

In the rapidly evolving world of wearable technology, few applications demand more from power management systems than hearing aids and similar compact medical devices. These tiny yet sophisticated devices present unique challenges: they must be exceptionally small, provide reliable power for extended periods, and incorporate increasingly complex functionality—all while maintaining user comfort and convenience.


Epson's Power Management IC (PMIC) solutions address these challenges head-on with a family of highly integrated circuits specifically designed for ultra-compact, battery-powered devices. These solutions combine multiple power functions including wireless charging, battery management, and power delivery in packages measuring just a few millimetres—making them ideal for hearing aids, earbuds, medical wearables, and other space-constrained applications.



The Technology Behind Epson's PMIC Solutions

Epson has developed a comprehensive range of PMIC solutions that integrate multiple power-related functions into single, ultra-compact packages. At the heart of their offering are two complementary devices that work together to deliver a complete wireless power solution:


The S1A00121F Wireless Power Transmitter

The S1A00121F serves as the primary (Tx) component of Epson's wireless power system. This sophisticated control IC enables 0.1W wireless power transmission with features including:


  • Power-MOS driver control for efficient energy transfer

  • External step-up converter control for optimized voltage delivery

  • Thermal detection and safety circuit integration

  • Intelligent communication capabilities that receive battery status, charging conditions, and other vital data from the receiver

  • Automatic coil driving mode switching (Full bridge/Half bridge)

  • Driver phase control to reduce interference between coils


The S1A00112B Wireless Power Receiver

The S1A00112B functions as the secondary (Rx) component, designed to receive power wirelessly and efficiently manage lithium-ion battery charging. Packaged in an ultra-compact 2.6mm × 3.4mm WCSP format, its key features include:


  • 0.1W secondary power receiver with synchronous rectifier circuit

  • Integrated lithium-ion battery charger with CC-CV charging method

  • Power management including charge pump (90% efficiency)

  • Comprehensive protection features (over-charge detection, over-discharge detection)

  • Communication capabilities to transmit battery conditions, charging status, and operating parameters

  • Ultra-low power consumption (shutdown current as low as 0.06μA)


The S1A00210B: Next-Generation Power Management

Currently under development, the S1A00210B represents Epson's next advancement in integrated power management technology. This upcoming solution expands on current capabilities with:

  • Enhanced charging control with customizable profiles

  • Configurable charging current (up to 300mA) and constant voltage settings

  • Temperature-based charging management across seven zones

  • Lifetime support features with cycle time management

  • Multiple power supply options including charge pump and LDO

  • Integrated flash memory for device configuration

  • Extended low-power operation capabilities


Technical Specifications and Implementation

Epson's PMIC solutions are engineered to deliver exceptional performance within extremely constrained dimensions. The combination of the transmitter (S1A00121F) and receiver (S1A00112B) creates a complete wireless power transfer system with robust communication capabilities.


S1A00112B Key Specifications

Feature

Specification

Package Size

2.6mm × 3.4mm WCSP

Charging Method

CC-CV for Lithium-ion

Over-Charge Protection

4.27V/4.37V/4.42V detection

Power Management

x1/3 Charge-pump with 90% efficiency

Operating Current

During charge: max 3mA

DCDC ON: 70μA-104μA (frequency dependent)

DCDC OFF: max 0.4μA (Ta=25°C)

Shutdown: max 0.06μA (Ta=25°C)


S1A00121F Key Specifications

Feature

Specification

Package Size

9.0mm × 9.0mm SQFN9-64PIN

Power Delivery

0.1W wireless transmission

Communication

Bi-directional with receiver

Safety Features

Thermal detection, Power-MOS short-circuit detection

Control Interface

I2C bus for parameter setting and monitoring

Applications in Hearing Aids and Wearable Technology

The exceptional integration and miniaturization of Epson's PMIC solutions make them ideal for a range of applications where space, power efficiency, and functionality are critical:


Hearing Aids

For hearing aid designers, Epson's PMICs solve multiple challenges:


  • Eliminate Charging Ports: By implementing wireless charging, manufacturers can create fully sealed devices with improved water resistance and reliability.

  • Extend Battery Life: Ultra-efficient power management prolongs operating time between charges.

  • Reduce Device Size: The high integration level minimizes component count, allowing for smaller overall device dimensions.

  • Improve Safety: Comprehensive protection features safeguard both the battery and the user.


True Wireless Earbuds

Similar to hearing aids, premium earbuds benefit from:


  • Compact Charging Cases: The transmitter IC enables efficient charging case designs.

  • Longer Playtime: Efficient power management maximizes listening time.

  • Rapid Charging: Customizable charging profiles allow for optimized fast charging without compromising battery health.


Medical Wearables



Black smart ring with visible sensors inside, set against a white background. The surface is sleek and glossy, conveying a modern feel.

For continuous health monitoring devices, e.g. a smart ring, these PMICs provide:


  • Extended Monitoring Capability: Ultra-low power states allow for longer operation.

  • Simplified User Experience: Wireless charging eliminates the need for users to manage small connectors.

  • Enhanced Reliability: Fully sealed designs resist moisture and contaminants.


Smart Jewellery and Compact IoT Devices

Increasingly popular smart rings, pendants, and other miniaturized IoT devices benefit from:


  • Invisible Power Management: The tiny footprint allows power functionality to be hidden within aesthetically-driven designs.

  • Configurable Power Modes: Different operating states can be optimized for specific use cases.

  • Communication Capabilities: Data exchange between transmitter and receiver supports intelligent charging behaviours.


The Future of Miniaturised Power Management

The upcoming S1A00210B demonstrates Epson's continued commitment to advancing miniaturized power management technology. Its enhanced features suggest a future where wearable devices can:


  • Adapt charging behaviour based on battery health and usage patterns

  • Implement more sophisticated power management strategies

  • Support increasingly complex functionality within the same or smaller form factors

  • Offer improved user experiences through intelligent power handling


As the wearable technology market continues to expand, particularly in health-related applications like hearing aids, the demand for sophisticated power management in ever-smaller packages will only increase. Epson's PMIC solutions position the company at the forefront of this technological evolution.


Conclusion: Empowering the Next Generation of Tiny Electronics

Epson's PMIC solutions represent a significant advancement in miniaturised power management technology. By combining wireless power transfer, sophisticated battery management, and comprehensive protection features into ultra-compact packages, these solutions enable designers to create smaller, more functional, and more reliable wearable devices.


For hearing aid manufacturers, medical device companies, and developers of other compact wearables, these integrated PMICs provide a complete power platform that addresses the full range of energy management challenges. The result is a new generation of devices that offer improved functionality, longer battery life, and enhanced user experiences without compromising on size or reliability.


To learn more about implementing Epson's PMIC solutions in your next design, contact our team for detailed specifications, evaluation boards, and expert application support.

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