Galvanic isolation in a 4-DIP through-hole package
The Vishay TCET1204 is a single-channel optocoupler with a DC-input phototransistor output, rated for 5000Vrms isolation between input and output. It comes in a 4-DIP through-hole package (0.300", 7.62mm pitch), the traditional form factor for industrial control, PLC I/O modules, and motor-drive feedback interfaces where socketed or hand-solderable serviceability matters.
CTR range and drive margin
Current transfer ratio spans 160% minimum to 320% maximum, both specified at 10mA forward current. That 2:1 min-to-max spread is typical for a standard-transistor-output coupler and means the designer sizes the input LED current and output pull-up resistor to guarantee saturation at the low end while avoiding saturation delay at the high end. A 10mA LED drive with a 10kΩ collector load on a 5V rail leaves comfortable margin across temperature and device-to-device variation.
Switching speed and output ratings
Turn-on time is 6µs typical, turn-off 5µs typical; rise and fall times are 3µs and 4.7µs respectively. These are adequate for 10-100kHz switching in isolated gate drives, AC mains zero-cross detection, and status-feedback signals. The output transistor handles up to 70V and 50mA continuous, with a Vce saturation maximum of 300mV at rated current — clean logic-level signaling without an extra buffer stage.
For a BOM planner, this means the part is a safe design-in choice for production runs through at least the next several years, and the through-hole DIP package stores well on the shelf without moisture-sensitivity bake requirements — just standard ESD handling.