The ISO7420, ISO7420M and ISO7421 provide galvanic isolation up to 2500 VRMS for 1 minute
per UL. These digital isolators have two isolated channels. Each isolation channel has a logic
input and output buffer separated by a silicon dioxide (SiO2) insulation
barrier. Used in conjunction with isolated power supplies, these devices prevent noise currents on
a data bus or other circuit from entering the local ground and interfering with or damaging
sensitive circuitry. The suffix M indicates wide temperature range (–40°C to 125°C).
These devices have TTL input thresholds and require two supply voltages, 3.3 or 5 V, or
any combination. All inputs are 5-V tolerant when supplied from a 3.3-V supply.
Note: The ISO7420 and ISO7421 are specified for signaling rates up to 1 Mbps. Due to
their fast response time, under most cases, these devices will also transmit data with much shorter
pulse widths. Designers should add external filtering to remove spurious signals with input pulse
duration <20 ns if desired.