Bidirectional I2C isolator, ISO1540

Bidirectionnal I2C Isolator

Sometimes you have an I2C bus on one side and a I2C controler (MCU) on the other side and you need to keep it electrically isolated from each other. This may be particularly the case if one of your I2C device is dealing with high voltage circuiterie. A good reason for electrical isolation may be the earth-ground that may inject some voltage or noise into the GND line via the earth-grounded high-power devices. Having electricaly isolated I2C devices (or I2C bus) is a good approach to reduce the noise .

This ISO1540 Bidirectional I2C Isolator breakout adds a full electrical isolation between two sides of an I2C bus. The TI ISO1540 chip at the earth is fully bi-directional and can be used with 1 MHz clock signal (and also support clock-stretching). The breakout works with 3 to 5V DC power or logic (separate on either side of course) and offers an isolation up to 2500 Volts RMS.

Use it is very easy:

• Wire the power/ground/clock/data of your MCU I2C on one side.
• Wire the power/ground/clock/data of the I2C bus on the other side.

Obviously, the two sides of the board must be electrically isolated (so using separate power supply not sharing any power line, neither the ground). Check that the both side of the bus are powered (green LED lits on the both sides). Now you are ready to send I2C data over the the bus. Please note that both side of the bus are fitted with 10K pullups resistor (to the proper VCC on each side).

The breakout is also fitted with Qwiic / StemmaQT for rapid I2C connexions. This allows  to create solderless circuit between development board and ISO1540 .

Technical details

• Isolated bidirectional, I2C compatible, communication
• Max clock speed: 1MHz
• Power Supply: 3 to 5.5 V
• Open-drain outputs: 3.5 mA on Side 1 and 35 mA on Side 2 (Current drain capability)
• Temperature: -40°C to +125°C
• +/- 50 kV/μs transient immunity (Typical)
• HBM ESD protection of 4 kV on all pins; 8 kV on bus pins
• ISO1540 Datasheet (Texas Instruments, English)
• Safety-related certifications:
  
  • 4242-VPK isolation per DIN VDE V 0884-11:2017-01
  • 2500-VRMS isolation for 1 minute per UL 1577
  • CSA approval per IEC 60950-1 and IEC 62368-1 end equipment standards
  • CQC basic insulation per GB4943.1-2011

Content

For each order, you will receive the I2C isolator board and a section of PinHeader.

QT Cable is not included but you can find them on the shop.