SPI Isolated Smart Switch with Integrated Power
The SI83418BDA-IF is a 4-channel SPI digital isolator from Skyworks Solutions using magnetic coupling technology, designed as an isolated smart switch with integrated isolated power. Rated for 1500Vrms isolation voltage with a minimum common mode transient immunity of 100kV/µs, this part maintains signal integrity across the isolation barrier in motor drive and inverter applications where fast voltage transients are present on the power stage.
Supply Rails and Timing at Temperature
The device operates from a dual supply: 2.25V to 5.5V on the logic side and 9V to 32V on the power side, covering both 3.3V/5V logic interfaces and industrial 24V field supplies without external level shifting. Propagation delay is 3.7µs max for both tpLH and tpHL, and the rise/fall time is 3µs typical — the SPI clock rate must be constrained so that data settles within this window, particularly when daisy-chaining multiple isolators on the same bus.
All four channels are unidirectional with all inputs on side 1 (4/0 configuration), meaning this part handles downstream signalling from a controller to isolated loads — no return channel for status feedback on the same die, so a separate upstream isolator is needed for bidirectional SPI (MISO).