What the 5700Vrms and 100kV/µs CMTI mean for your isolation barrier
The Texas Instruments ISO7821LLDWR is a 2-channel, unidirectional digital isolator built on capacitive coupling technology. Its 5700Vrms isolation voltage and 100kV/µs common-mode transient immunity (CMTI) make it a fit for systems where high-voltage safety isolation and noise rejection are non-negotiable — think motor drives, grid-tied inverters, medical patient monitoring, and industrial fieldbus interfaces that must survive fast switching edges without corrupting data.
100Mbps data rate — throughput for the bus
At 100Mbps, this part handles isolated SPI, UART, and CAN traffic without bottlenecking the link. The 25ns propagation delay (max) and 4.5ns pulse-width distortion keep timing margins tight enough for most synchronous interfaces. If your design runs a faster serial protocol (e.g., 150Mbps+), you will need a higher-speed isolator; for the majority of industrial and instrumentation buses, 100Mbps is the sweet spot that avoids over-spending on speed you do not use.
Supply range and isolated power — what you need on the rails
The supply range spans 2.25V to 5.5V on both sides, so it works with 3.3V or 5V logic without a separate regulator. Note that the part does not include an integrated isolated DC-DC converter — you will need a separate isolated power module or a transformer driver to power the secondary side. Plan for a small 1µF decoupling cap per supply pin, placed close to the package.
Package and temperature grade — board-level fit
Housed in a 16-SOIC wide-body (7.50mm width) package, it offers 8.5mm creepage distance typical for reinforced isolation at this voltage. Surface-mount assembly is straightforward;.
The part is ROHS3 compliant.