When the SDA (Serial DAta) strains on both the left and right lines are 1, the circuit is quiescent and optoisolators IC1 and IC2 are typically not actuated. When the SDA line on the left change intos zero, current wafts throughout the LED in IC1 by means of R2. The SDA line on the proper is then pulled low via D2 and IC1. Optoisolator IC2 does now not transfer this 0 to the left, as a end result of the polarity of the LED in IC2 is the flawed approach round for this level. This arrangement stops the circuit conserving itself in the zero state for ever. As is viewed, the circuit is symmetrical. So, when the SDA line on the proper is 0, this is transferred to the left. The decrease a part of the diagram, meant for the SCL (Serial CLock) line, is the similar to the higher part.
Electrical Isolation For I2C Bus Circuit Diagram
Resistors R1, R4, R5, and R8, are the standard three.3 kΩ pull-up resistors which can be necessary in each I2C line. If these resistors are already existing in other situations within the device, they could additionally be omitted here. The current drawn by way of the circuit is fairly higher than average for the reason that pull-up resistors are shunted by the LEDs within the optoisolators and their series resistors. Nevertheless, it remains throughout the norms laid down in the I2C specification.
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