12/28/2022 0 Comments I2c optical isolator![]() If you need to be really miserly, you might resort to building your own (say with planar coils and RF design). There may also be power advantages, say, if you need to be miserly with battery power (a logic level opto probably uses less bias on the output side). Optocou-plers with open-collector outputs are simple to directly connect to the I2C bus line. ![]() Also, no polarity inversion is necessary, since the transistor on the output of the optical isolator is connected to GND. Designing optical isolation for the I2C bus parallel clock and data signals requires consideration of optocoupler propagation delay and skew performance. #I2c optical isolator driverFor SDAI and SCL the driver is connected to the LED cathode and the LED only flashes, if activity is on the I2C bus. (You can't invert a 6N136 output in the same way without defeating the high speed feature.) For more, I'd go with logic level parts, or iCoupler style devices. In the application notes for the TPS2384 opto isolator devices are used to get access to the I2C bus. Or the 4N35 can be wired "emitter follower" style (though it's not actually following anything), in case you need the diode end in a particular direction and you need the inverted (or not) output. Both of these, you just add a pull-up to the open collector output. networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices. These optocouplers provide 3.7kVdc Isolation which makes it ideal for industrial digital Inputs. Hot Swappable I2C Isolator achieves 1,500 Vrms bus isolation. The PCA9536 Digital IO pins are connected to the optocouplers. 1 2 Energy or information can still be exchanged between the sections by other means, such as capacitive, inductive, radiative, optical, acoustic or mechanical. This 8 channel digital isolated input board has an on-board 5V. ![]() These optocouplers provide 3.7kVdc Isolation which makes it ideal for industrial digital Inputs. The MCP23008 Digital IO pins are connected to the optocouplers. ![]() This board has an I2C digital IO expander chip MCP23008. This board has an I2C digital IO expander chip PCA9536. Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow no direct conduction path is permitted. This is a 8 Channel I2C Optically isolated digital input board. (Hmm, I have the schematic of the circuit I was referring to, but it doesn't look like I posted it there.) For doing better on the cheap, I would go with 6N136, or the high dV/dt equivalent SFH6345 (be warned, the dV/dt rating on 6N136s is very misleading). This is a 4 Channel I2C Optically isolated digital input board. The I2C specification for fast-mode operation requests that internal filtering at devices on the bus suppress pulses of less than 50ns. 4N35 level optos are pretty bad, you wouldn't want to use them above 100kbps or so without special hardware. ![]()
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