The CNY1743S is officially marked as Obsolete by onsemi, meaning the manufacturer has ended production and no further last-time-buy windows are open. Sourcing this part now runs through independent distribution — surplus and broker inventory only. Availability and date-code provenance are confirmed at RFQ; no factory lead time applies.
5300Vrms isolation — what it means for the BOM
The 5300Vrms isolation rating qualifies this optoisolator for reinforced insulation in mains-connected circuits — think AC line monitoring, motor drive feedback, or medical patient-interface isolation where the safety barrier must withstand a 5.3 kV transient without breakdown. The 1 µs rise / 2 µs fall typical switching speed and 2 µs / 3 µs turn-on/off times place it in the general-purpose phototransistor class — adequate for 50/60 Hz line sensing, relay drive, and low-speed logic isolation, but not for high-speed digital buses like I2C or SPI.
CTR range and drive margin
Current transfer ratio spans 160% minimum to 320% maximum at 10 mA forward current — a 2:1 guaranteed spread. This means the LED drive circuit must be designed to the min CTR (160%) to ensure the output saturates reliably, while the max CTR (320%) sets the upper bound on collector current for a given If. Output transistor is rated 70 V Vce max and 50 mA continuous collector current — enough to drive a small relay coil, PLC input, or logic gate directly without a buffer transistor.
Supplied in a 6-SMD Gull Wing package (6-SMD, Gull Wing) — the same footprint as the standard DIP-6 through-hole but surface-mount, so it reflows on the board alongside other SMD passives. The supplier device package is 6-SMD. Operating temperature range of -55°C to 100°C covers industrial and military-temperature environments — the opto will function in unheated enclosures, engine bays, or outdoor telecom cabinets without derating.