Three-channel capacitive isolator for high-speed signal isolation
The Texas Instruments ISO7731DWR is a three-channel, unidirectional digital isolator using capacitive coupling technology. It is designed to transmit digital signals across an isolation barrier at data rates up to 100 Mbps, with a reinforced isolation rating of 5000 Vrms. Typical applications include industrial fieldbus interfaces, isolated SPI/UART links, motor-drive feedback paths, and medical equipment requiring galvanic isolation for patient safety.
The 100 Mbps data rate is fast enough to handle full-speed SPI, CAN FD at 5 Mbps, and most UART-based protocols without timing compression. Propagation delay is 16 ns max, and pulse-width distortion is held to 4.9 ns max, so the output pulse width stays close to the input — important for maintaining duty cycle in PWM or encoder signals. Rise and fall times are 1.3 ns and 1.4 ns typical, which keeps edge-rate-induced ringing manageable on short PCB traces.
Isolation and transient immunity for noisy environments
The 5000 Vrms isolation voltage qualifies the ISO7731DWR for reinforced insulation per IEC 60747-5-5 and VDE 0884-11, making it suitable for medical and grid-tied applications where safety certification is required. Common-mode transient immunity is rated at 85 kV/µs minimum — this is the key spec for motor drives and inverter-fed systems where fast-switching IGBTs or SiC FETs couple high dv/dt noise across the barrier. A low CMTI number would cause data corruption in those environments; 85 kV/µs gives enough margin for most industrial drives.
Temperature range and deployment environment
The wide range also covers cold-start conditions in arctic deployments and self-heating in sealed enclosures.
Package and footprint
Housed in a 16-pin SOIC wide-body package (16-SOIC, 7.50 mm body width), the ISO7731DWR provides the creepage and clearance distances needed to maintain 5000 Vrms isolation. The wide-body SOIC is a standard footprint for high-voltage isolators, and the surface-mount package is compatible with reflow soldering processes.