SPI bus isolation — why this part exists
The ADUM3150BRSZ is a 6-channel unidirectional digital isolator from Analog Devices' iCoupler® SPIsolator™ family, purpose-built for SPI buses. It uses magnetic coupling to transfer data across a 3750 Vrms isolation barrier at rates up to 40 Mbps. The six channels are arranged as 4 on side 1 and 2 on side 2, which maps directly to the four standard SPI signals (SCK, MOSI, MISO, chip select) plus two extra control lines — useful for daisy-chain enables or interrupt signals.
The 40 Mbps data rate supports SPI clock frequencies up to 20 MHz in double-data-rate mode or 40 MHz single-edge — enough for most ADCs, DACs, and sensor interfaces. Propagation delay is 14 ns max (both directions), which keeps setup-and-hold margins comfortable at those clock rates. Pulse-width distortion is held to 2 ns max, so the duty cycle stays clean through the barrier. Common-mode transient immunity of 25 kV/µs minimum means the part won't glitch when a motor-drive IGBT switches or a relay coil kicks — critical in inverter and industrial environments.
Package and footprint notes
Housed in a 20-pin SSOP (0.209" body width, 5.30 mm), surface-mount only. The 1.27 mm pitch is standard for SSOP and routes easily on two-layer boards. No isolated power output on this variant — you supply Vdd on both sides separately.
Lifecycle and sourcing reality
ROHS3 compliant. If you need a higher-isolation variant, the ADUM4150ARIZ-RL offers 5000 Vrms in the same 6-channel SPI configuration, though propagation delay increases to 24 ns.