Consumer Ar Smart Glass Hardware Design

A lightweight consumer AR smart glass featuring an optical display, local processing, and wireless connectivity for media playback and notifications.

Executive Summary

This reference design defines the system architecture, critical component candidates, risk register, and validation path for Consumer Ar Smart Glass. It is a system-level design deliverable; verify critical claims with manufacturer evidence and prototype testing before production release.

Design Overview

Requirements Coverage

System Architecture

Power Topology: Built-in temple rechargeable Li-Ion cell feeds PMIC (BQ25155), stepping down to a clean 3.3V primary system rail with dedicated low-noise LDOs for the optical display and sensor suite.

Module List

Power Tree and Signal Interfaces

Design Schemes

Heterogeneous Dual-Chip Micro-LED Architecture ★

Utilizes a low-power application processor paired with an ultra-efficient MCU and Micro-LED waveguide optics for high outdoor brightness and strict thermal limits.

Trade-offs: Higher component complexity and FPC routing requirements across the temple hinge, but significantly better outdoor readability and battery longevity compared to Micro-OLED Birdbath setups.

Key IC selection

Main Dual-Core MCU & Wireless Processor

• Need: Execute local UI logic, drive Micro-LED display interfaces, process 6-axis IMU sensor fusion, and manage dual-mode wireless connectivity under tight temple space and power constraints.
• Class: Dual-chip ultra-low-power wireless MCU architecture (Wi-Fi/BLE SoC + dedicated BLE/sensor co-processor)
• Shortlist: Espressif ESP32-S3 (Dual Xtensa LX7 + Wi-Fi/BLE) + Nordic nRF52840 (Cortex-M4 BLE), Qualcomm QCC5100 series + custom low-power companion MCU
• Pick: Select commercial automotive/consumer-grade dual-chip sets balancing package size (WLCSP/QFN), standby current, and rich peripheral support for display and sensors.

Battery Charger & DC-DC Power Path

• Need: Safely charge a miniature temple Li-Ion battery via USB-C with micro-amp termination currents and supply stable 3.3V and 1.8V rails despite battery voltage sagging.
• Class: I2C-controlled linear battery charger with integrated LDO combined with a high-efficiency synchronous buck-boost converter
• Shortlist: TI BQ25155 (Ultra-low quiescent current charger + LDO) + TI TPS63030 (High efficiency buck-boost), Analog Devices LTC4124 + MAX77827
• Pick: Choose ultra-small footprint WLCSP package PMIC components capable of sub-microamp shutdown currents to maximize standby life in smart glasses.

Type-C Controller & Port Protection

• Need: Detect USB-C plug orientation, handle CC pin logic, and negotiate baseline power delivery for charging the device safely.
• Class: Standalone USB Type-C controller IC with I2C host interface
• Shortlist: FInsemi / Onsemi FUSB302, TI TPS65982 / STMicroelectronics STUSB1602
• Pick: Select space-saving WLCSP-9 or tiny QFN Type-C controllers with minimal external passives and low active power consumption.

Risk register

Bring-up and Validation Plan

1. Power-off inspection and rail resistance checks
2. Current-limited first power-up; verify every rail before enabling loads
3. Validate interfaces and timing one subsystem at a time
4. Run thermal, fault-injection, EMC pre-scan, and endurance tests for the target environment

Key Components

5/7 modules matched to real parts. See the BOM tab for the full component table.

Texas Instruments BQ25155 + TPS63030 (BQ25155YFPT)

BQ25155YFPR is the active production IC variant in tape and reel packaging matching the primary MPN BQ25155 from Texas I

Espressif ESP32-S3 & Nordic nRF52840 Dual-Chip (ESP32-S3)

The candidate matches the primary MPN (ESP32-S3) and the preferred manufacturer (Espressif Systems).

JBD Micro-LED Monochromatic Panel with Diffractive Waveguide (JBD25FA-W)

Rejected weak/wrong-class catalog hits; using web recommendation: JBD25FA-W

Knowles Knowles SPM0687HT5H MEMS Microphone & AAC Miniature Open-Ear Speaker (SPM0687HT5H)

Rejected weak/wrong-class catalog hits; using web recommendation: SPM0687HT5H

Build Summary

• Difficulty: Advanced
• Estimated time: 12-16 hours
• Tools required: Anti-static inventory bins, ESD microscope, Optical Inspection System, Calipers, Stencil Printer, Squeegee

See the Build tab for the full step-by-step assembly guide.

Evidence and Limitations

• Confirm part parameters, certifications, and compatibility against current manufacturer documents.
• Treat industry compliance without test or certificate evidence as a compliance gap, not an approval.
• See Reference Images for visual artifacts and Build Guide for detailed assembly and bring-up steps.