The TCLT1018 is a single-channel transistor-output optocoupler from Vishay in a 4-SOP gull-wing package. That 5000 Vrms isolation rating is the one-ship guarantee — it separates the low-voltage control side from the high-voltage bus in a motor drive or a PSU feedback loop, and it passes reinforced insulation testing per IEC 60950-1 without the creepage distance a DIP-4 would need.
CTR window and switching speed — the real selection knobs
Current transfer ratio runs from 130% minimum to 260% maximum at 5 mA forward current — that is a tight bin, so the LED drive resistor stays the same across reel lots and the output transistor saturates predictably without overdriving the input side. Rise and fall times are 3 µs and 4.7 µs typical, with turn-on and turn-off times of 6 µs and 5 µs respectively. That puts the usable switching frequency around 50-60 kHz for a logic-level signal — fast enough for IGBT gate-drive feedback or a digital isolator replacement in a non-isolated DC bus sense circuit. Output transistor holds off 70 V and sinks 50 mA continuous — enough to drive a 24 V PLC input or a small relay coil directly without a buffer transistor.
Active production and compliance
The -55°C to +110°C operating range covers industrial and telecom ambient — the 110°C ceiling gives margin above the 85°C typical for outdoor cabinet electronics.