KNOWLEDGE BASE · HuaXinGou
Optocoupler Selection & Sourcing Guide
Optocouplers explained: CTR, isolation voltage, speed, applications and buying tips.
Optocouplers explained: CTR, isolation voltage, speed, applications and buying tips.
Optocouplers isolate signals between circuits. This guide covers selection and procurement.
By Vigny (深圳市华芯购电子有限公司) · Published 2026-09-27 · Data verified 2026-09-29 · Sources: manufacturer datasheets & HuaXinGou stock verification
An LED and phototransistor inside one package transfer signals without electrical connection, providing galvanic isolation. They are essential in power supplies, motor drives and industrial controls.
Current transfer ratio (CTR), isolation voltage (e.g., 3750-5000Vrms), response speed (for switching vs linear), collector-emitter voltage and package (DIP-4, SOP-4).
SMPS feedback loops (with TL431), MCU isolation, PLC I/O, relay drive and communication isolation.
Common parts: PC817, EL357, TLP521, 6N137 (high speed). Chinese and Taiwanese makers supply most volume. HuaXinGou quotes brand options and batch codes.
Paste your part list below — our team verifies stock, date codes and alternates, then replies with a consolidated quote. Call/WeChat also available.