I2c isolator4/15/2023 Channel-to-channel isolated I 2C ADC and amplifier. Some applications require channel-to-channel isolation, where each channel is isolated from every other channel, as shown in Figure 4. (a) Isolated I 2C ADC and amplifier, and (b) Isolated I 2C DAC and amplifier. These applications also require an isolated power supply to power the converters and amplifiers on the secondary side. ![]() Figure 3 shows two isolated data-acquisition systems. It is often necessary to bring data from a precision converter (ADC or DAC) across an isolation barrier via an I 2C bus. Telecommunication and data communication equipment.Level-translating I 2C interfaces for power supplies.Isolated I 2C, SMBus, or PMBus interfaces.To achieve a robust data communications link, each I 2C device connected to the I 2C bus must be isolated.Įxamples of isolated I 2C applications include: All additional I/O signals crossing the isolation barrier require isolators that can also be powered by the ADM3260. The isolated power channel (3.3 V_ISO) allows the primary-side circuitry to be powered from the secondary side, removing the requirement for a separate low-voltage power source, which is not commonly available in the –48-V domain and is problematic to generate. Isolation also provides protection against high voltages or currents caused by the line surges or ground loops that can occur in a system with multiple grounds. Isolation prevents permanent damage that could occur if the I 2C port was inadvertently connected directly to the –48-V supply. Isolation is required because the primary side is referenced to –48 V, while the secondary side is referenced to ground in a low-voltage domain. Typical isolated PMBus communications link. Its isolated power supply (3.3V_ISO) powers the ADuM3200 2-channel digital isolator that isolates the SHDN and RESTART signals. The ADM3260 dual I 2C isolator with dc-to-dc converter isolates the SDA and SCL signals. Figure 2 shows a PMBus communications link that isolates the ADM1075 –48-V hot swap and digital power monitor on the primary side from the secondary side, which operates with 12-V and 3.3-V supplies. This requirement is not compatible with optocouplers, which are unidirectional. ![]() To ensure trouble-free card insertion/removal and robust operation, each interface must be isolated, but isolating I 2C interfaces is complicated because the bus is bidirectional. PC boards used in telecommunications applications often include digitally controlled power converters and circuits that operate at different ground potentials. The PMBus protocol defines an open-standard, digital-power-management protocol that facilitates communication with a power converter or other connected device.įigure 1 shows how an isolation barrier galvanically isolates the I 2C interface from each system connected to it, allowing digital data to travel between two points but preventing the flow of ground current this reduces signal distortion and errors by removing noise that gets coupled onto the communications bus. The power management bus (PMBus), a relatively slow 2-wire communications protocol based on I 2C, is targeted at digital management of power supplies. Developed by Philips in the early 1980s for ICs on a single board, I 2C usage is still increasing. ![]() The Inter-Integrated Circuit (I 2C) bus is a 2-wire, bidirectional bus used for low-speed, short-distance communication between integrated circuits. Maurice O'Brien Download PDF IntroductionĪ key requirement for industrial and instrumentation (I&I), telecommunications, and medical applications is a reliable interface for transmitting data. Designing Robust, Isolated I2C/PMBus Data Interfaces for Industrial, Telecommunications, and Medical Applications
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