Isolation barrier and channel assignment
The Texas Instruments ISO7742FDBQR is a 4-channel, unidirectional digital isolator using capacitive coupling technology, rated for 2500Vrms isolation voltage. It delivers 100 Mbps data rate with 16 ns propagation delay and 2.4 ns rise/fall times, making it suitable for isolating SPI, UART, or general-purpose digital signals in industrial and automotive environments. Channel configuration is 2 inputs on side 1 and 2 inputs on side 2, giving a 2/2 split that supports bidirectional isolation for interfaces like RS-485 or CAN where data flows both ways across the barrier.
In motor-drive or inverter applications where fast-switching IGBTs or SiC FETs create high dV/dt across the isolation barrier, this rating ensures the output doesn't glitch or lose data. The 85 kV/µs floor comfortably handles the 50–75 kV/µs edges typical in 600 V-class industrial drives. Pulse-width distortion is max 4.9 ns, which keeps the duty-cycle error small enough for PWM isolation or timing-sensitive links.
Supply voltage accepts 2.25 V to 5.5 V on each side independently, so it can bridge a 3.3 V MCU domain to a 5 V field-side interface without a level shifter.
The small footprint suits space-constrained multichannel isolation banks on a single PCB.