The ISO7221BD is a dual-channel Digital Isolator to facilitate PCB layout, the channels are oriented in the same direction. It has a logic input and output buffer separated by TI's silicon-dioxide (SiO2) isolation barrier, providing galvanic isolation of up to 4000 VPK per VDE. Used in conjunction with isolated power supplies, this device block high voltage and isolate grounds, as well as prevent noise currents on a data bus or other circuits from entering the local ground and interfering with or damaging sensitive circuitry. A binary input signal is conditioned, translated to a balanced signal and then differentiated by the capacitive isolation barrier. 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 is sent across the barrier to ensure the proper dc level of the output.
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