Passive electrical Components

Si8400 Si8405 and bidirectional I2C isolator

I2C (Inter-Integrated Circuit Bus) was developed in the early 19801. In the early 1990s has created an enhanced version of Intel SMBus2 called I2C (System Management Bus) for electricity and systems Management of heat in the server and PC applications. In the early 2000s was SMBus2 the physical interface for PMBus, an open specification chosen for the management of modular power supplies, opening another market for I2C / SMBus products. Today, the venerable I2C-bus in popularity because of its low cost and overhead to develop, support the industry strong and relatively efficient communication protocol. Therefore I2C was adopted in many new end-use applications.

Many of these applications require galvanic isolation interface I2C/SMBus ground loops for safety or disposal. For example, Power over Ethernet (PoE) applications typically use an I2C interface for communication equipment sourcing PoE (PSE) and controllers of the Earth-mass-related. Galvanic isolation is both standard and also as a practical matter, necessary to prevent ground loops in the Ethernet connected devices. The interface Physics has two son, serial data (SDA) and serial clock (SCL). These son are at the collector-driver open to serve simultaneously inputs and outputs. At first glance, it appears that SDA and SCL simply two-way insulators in parallel and in opposite directions are isolated. However, This technique provides information that bar low for a logic low level is asserted master or slave. This problem can by adding anti-lock circuits3 fixed leads to a larger, more expensive, solution.

Recent advances in silicon technology RF isolation allow both the isolation and anti-lock functions to be integrated into individual packets, such as Silicon Laboratories Si8400 Si8405 and isolators4 bidirectional I2C. These products offer a single chip, anti-lock solution for the problem to isolate applications I2C / SMBus and require no external components except the I2C / SMBus resistance pull-up. In addition, the devices provide isolation for up to 2.5 Clock kVACRMS stretch and support to provide maximum bus speed of 2 Mbps.

Two other significant levels of system design considerations clock stretching and hosting system status and control signals additional, usually requiring isolation.

It is clear that the data line (SDA) to be bidirectional, that this line contains data that is required of the host to the slave or the slave to the host. It is also common that the device slave to keep the clock line (SCL) lower during the "acknowledge" (ACK) period, while it is collecting data for the master. For "Clock Stretching" in a particular design I2C, I2C isolator, which is also a bidirectional channel to work online SCL should be used. Without bi-Isolation on the SCL signal, the developer must ensure that all I2C slave can take the bus clock and timing is the same characteristics the master. This provides additional design and validation of stress on the developers of the system.

The Si8400 is bidirectional for two SCL and SDA. In addition to SCL and SDA signal isolation, many designs the system status and additional control signals such as reset and interrupt lines are isolated, they need it. The use of insulators with other I2C monolithic unidirectional channels allows the designer system to simplify the timing of the challenges in a design. Forced instead to store other channels of the state and control in several Isolator or opto-packages (to isolate the results for a large part to changes in schedule), I2C monolithic insulators with additional channels have characteristics unidirectional time to closely follow the course of process, voltage and temperature variations. The Si8405 has two additional single-channel isolate the reset signal and interrupt. I2C-design should not be a secret. Considering each of these design tips and choosing a suitable insulating, the requirements for the implementation of the designer simply I2C their products.

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Silicon Labs – Optocoupler and Touchless Sensor IC. Industry leader in the innovation of high-performance, analog-intensive, mixed-signal ICs. Developed by a world-class engineering team with unsurpassed expertise in mixed-signal design.