Introduction
The ISOW77xx device family is a quad-channel digital isolator with an integrated high-efficiency power converter featuring low emissions. The integrated DC/DC converter provides up to 550mW of isolated power, eliminating the need for a separate isolated power supply in space-constrained isolation designs.
The power converter operates efficiently across a wide ambient temperature range of –40°C to +125°C. The device offers improved emissions performance, simplifies board design, and supports ferrite beads for further emission attenuation. The ISOW774x is designed with enhanced protection features, including soft-start for inrush current limiting, overvoltage and undervoltage lockout, fault detection on the EN/FLT pin, overload and short-circuit protection, and thermal shutdown.
The ISOW77xx family provides high electromagnetic immunity while isolating CMOS or LVCMOS digital I/O. The signal isolation channels feature logic input and output buffers separated by a dual-capacitor silicon dioxide (SiO₂) dielectric barrier, while power isolation uses an on-chip transformer with thin-film polymer as the insulation material. The quad-channel ISOW77xx is available in five orderable configurations, where the last digit of the device part number indicates the number of reverse channels. For example, the ISOW7740 has 4 forward channels and 0 reverse channels, while the ISOW7743 has 1 forward channel and 3 reverse channels. If the input signal is lost, ISOW77xx devices without the F suffix default to a logic-high output, while those with the F suffix default to a logic-low output. By connecting V₁₀ and VDD together on the PCB, the ISOW774x can operate from a single supply of 3V to 5.5V. For lower logic levels, these devices support a logic supply (V₁₀) of 1.71V to 5.5V, independent of the 3V to 5.5V power converter supply (VDD). VISOIN and VISOOUT must be connected to the board through a ferrite bead or fed through an LDO.
These devices help prevent noise currents on data buses (e.g., UART, SPI, RS-485, RS-232, and CAN) or other circuits from entering the local ground and interfering with or damaging sensitive circuits. Through innovative chip design and routing techniques, the device's EMC performance is significantly enhanced, mitigating system-level ESD, EFT, surge, and radiated emissions compliance. The device is available in a 20-pin wide-body SOIC (SOIC-WB) DFM package.