DESCRIPTION 

The ISO72x-Q1 is a digital isolator with a logic input and output buffer separated by a silicon oxide (SiO2 ) insulation barrier. This barrier provides galvanic isolation of up to 4000 V. Used in conjunction with isolated power supplies, this device prevents noise currents on a data bus or other circuits from entering the local ground and interfering with or damaging sensitive circuitry. The capacitive isolation barrier conditions, translates to a balanced signal, then differentiates a binary input signal. Across the isolation barrier, a differential comparator receives the logic-transition information, then sets or resets a flip-flop and the output circuit accordingly. A periodic update pulse sent across the barrier ensures the proper dc level of the output. On failure to receive this dc refresh pulse for more than 4 μs, the response of the device is as if the input is or not actively driven, and the failsafe circuit drives the output to a logic-high state.