This article covers StarTech.com ディスプレイアダプター.
Overview
The StarTech.com 109B-USBC-HDMI is a USB video adapter that adds up to two 4K60Hz HDMI monitors to your laptop. It supports both USB-C and USB-A connections, and thanks to DisplayLink technology, it works even on Apple M1/M2/M3 MacBooks that lack native multi-monitor support. A standout feature is the 100W USB Power Delivery passthrough, which reserves 10W for the adapter itself and delivers up to 90W to charge the host laptop. The aluminum housing provides both EMI shielding and effective heat dissipation, ensuring stable performance during extended use.
Connectivity & Compatibility
Host connection via USB-C or USB-A (USB 3.2 5Gbps), compatible with Thunderbolt 3/4 and USB4. Two DisplayLink-based HDMI outputs, each supporting up to 4K@60Hz with 5.1ch audio. Works with Windows, macOS, Ubuntu, and ChromeOS. macOS requires a driver download; Ubuntu and ChromeOS support automatic driver installation. Includes a 30cm captive cable to reduce strain on ports and connectors.
Product Info
Released around 2023, this adapter sits in the mid-range segment for business-oriented USB video solutions. It carries DisplayLink certification, ensuring broad compatibility. The standard warranty is 2 years. The package includes the adapter and a quick-start guide only — no extra cables or power bricks needed.
Best Use Cases
M1/M2/M3 MacBook users: Many Apple Silicon MacBooks don't natively support multiple external displays. This adapter provides an easy way to set up a dual-monitor workstation. Just remember that macOS requires a driver installation. Business professionals: If you're stuck with a single laptop screen, this adapter lets you run two external monitors plus the built-in display for a total of three screens. Ideal for spreadsheet work, data analysis, and document editing. * Users with older USB-A laptops: Even if your laptop lacks USB-C, the USB-A connection works perfectly. This makes it a versatile choice for legacy hardware. Note that it's not suitable for gaming due to DisplayLink latency. ## Alternatives
Direct competitors include the Plugable UD-3900PDZ and WAVLINK USB-C Dual HDMI Adapter. The Plugable model offers similar DisplayLink functionality, but the StarTech.com 109B-USBC-HDMI has the edge with USB-A support for broader compatibility. WAVLINK's adapter is cheaper but often provides lower PD passthrough wattage, making the StarTech.com a more reliable choice if charging performance matters.
Things to Consider
This adapter is not designed for gaming. DisplayLink-based video output introduces noticeable latency, so it's unsuitable for fast-paced titles. macOS requires manual driver installation. Make sure you have internet access during initial setup. While the adapter supports 100W PD passthrough, the host laptop receives up to 90W. High-power gaming laptops may not charge fully under heavy load. The compact body (112×61×15mm) is convenient, but the fixed 30cm cable may require a USB extension cable depending on your desk layout.
