Isolation barrier and output voltage headroom
The TLP388(TPL,E delivers 5000 Vrms isolation in a 4-lead SOIC package — a reinforced-grade rating that supports safety certification for mains-referenced circuits without an external isolator. Output transistor is rated to 350 V maximum, which means it can directly switch loads on a 350 VDC rail, eliminating a secondary relay or MOSFET buffer.
CTR spread and switching speed for design margin
Current transfer ratio spans 50% to 600% at 5 mA forward current — a spread that forces the designer to bias the LED for the minimum CTR and verify saturation at the maximum. Rise and fall times are 2 µs and 3 µs typical, with matched turn-on and turn-off times of 3 µs each — adequate for low-speed logic isolation.