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ISO1640: POWER SUPPLY FOR THE IC

Syed Inamullah
Prodigy 60 points
Part Number: ISO1640
Other Parts Discussed in Thread: SN6501, SN6505B

Hello experts,

We want to use the ISO1640 I2C isolator in our design. The system is having the two ground references GND1 and GND2 and single power supply of 3.3v VDD. Can i connect the VDD1 and VDD2 of the ISO1640 to a common power supply of 3.3V. However the GND1 of the ISO1640 is connected to the GND1 of the system and the GND2 of it is connected to the GND2 of the system. 

  • 0
    TI__Mastermind 22750 points

    Hello Syed,

    In order to maintain proper system and component level isolation, you must maintain isolation between the power supplies, if you short the VCCs together then there will be a system level path to bypass the appropriate isolation, eliminating the benefit of the isolation of the ISO1640. 

    Additionally, if the VCCs are shorted and the GNDs are separate, then there may be signaling issues if the GNDs can still shift relative to each other.

    In order to overcome this challenge, you need to make sure you have two isolated supplies.

    If you do not have separate power supplies, then you could consider using a part like the SN6505B or the SN6501 coupled with a transformer to generate the necessary isolated power supply to maintain separate VCC and GND isolation.

    Best,

    Michael

  • 0 in reply to Michael J Schultis
    Prodigy 60 points

    Thanks for your valuable reply.

  • 0 in reply to Syed Inamullah
    TI__Mastermind 22750 points

    Syed,

    Very happy to help!

    Best,
    Michael