61. UART Optoisolator Selection

A standard transistor-output optocoupler is too slow for UART communication — its phototransistor output has turn-off times of 10–50µs, which distorts data at 115200 baud.

A logic output optoisolator has an integrated photodetector and output driver that produces clean, fast digital logic transitions. Data rates of 1MHz+ are typical, providing comfortable margin for 115200 baud UART.

Required: Open Collector · 1-Ch · ≥3000Vrms · ≥1MHz data rate · tpd ≤10µs · 3.3V supply · SOIC-8 · SMD

Go to DigiKey.com → Isolators → Optoisolators - Logic Output (Digital Isolators)

Apply these filters:

• Output Type → Open Collector
• Number of Channels → 1
• Voltage - Isolation → 3000Vrms or higher
• Data Rate → 1Mbps or higher
• Package / Case → 8-SOIC or 8-SMD
• Part Status → Active

Important: Logic output optoisolators need a supply voltage on the output side (unlike transistor-output types which are passive). Verify the Voltage - Supply range includes 3.3V (e.g., "2.7V ~ 5.5V" or "3V ~ 15V").

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

➡ View Matching Parts — Logic Output, 1-Ch, ≥3000Vrms, ≥1MHz, SOIC-8