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ISO1541: Asking for ISO1541 design review and suggestions

Part Number: ISO1541
Other Parts Discussed in Thread: ISO1540, ISO1640, ISO1641

Hi Team,

Customer would like to design ISO1541 for I2C interface.
Would you please help review  questions and provide your comments?

 1.customer power domain is as below. Could you help double check it? And Could you help check our connection for VCC1, VCC2?

 2. Form the datasheet the VV1, VV2 is 3 to 5.5V. it means VCC1-GND1 and VCC2-GND2, right?

 3. Could you help describe the behavior for lockout?

Thanks for help!



  • Hi SHH,

    Thanks for reaching out. Here are my answers to your questions:

    1. The connections to VCC1, GND1, VCC2, and GND2 are all within the range specified by the recommended operating conditions. Therefore, this configuration is ok.

    2. Yes, you are correct. The recommended supply voltage range for VCC1 and VCC2 is referring to VCC1 referenced to GND1, and VCC2 referenced to GND2.

    3. UVLO will not impact the behavior of the device as long both supply voltages are within the range specified by the recommended operating conditions. The device will function correctly if both VCC1 and VCC2 are within this range. 



  • Hi Kenneth,

    Thanks for comment. Would you please help for further questions?

    1. For items3, if VCC1 and VCC2 the device is lockout. Does it will lock the i2c bus or influences other i2c devices?
    2. Do you know what different is for ISO1540 and ISO1541?
    3. For layout guideline, I see it want us to keep out under IC. Is it necessary?
    4. Could you help recommend common parts to us?



  • Hi SHH,

    Here are my answers to your questions:

    1. In the part of the datasheet that you highlighted in your initial post, "lockout" refers to under voltage lockout (UVLO). When the supply voltage is below the undervoltage lockout threshold specified by the datasheet, the device is disabled.  

    2. The ISO1540 has two isolated bidirectional channels for the clock and the data lines while the ISO1541 has an isolated bidirectional data channel and an isolated unidirectional clock channel.

    3. It is necessary to keep the space under the IC free from all planes, traces, pads, and vias. Doing this will help keep both sides of the PCB isolated from each other.

    4. For I2C interface isolation, we recommend using our newest device, the ISO1640/ISO1641.