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SN74LVC2G66-Q1: Using as I2C bus switch

NOBUO FUJIHARA
Expert 8605 points
Part Number: SN74LVC2G66-Q1
Other Parts Discussed in Thread: SN74LVC2G66, TINA-TI

Hi Champs,

My customer is looking for the I2C bus switch for automotive application.

If SN74LVC2G66 is used for I2C bus switch, is there any point to be taken care?

Customer especially concerns malfunction which may be caused by bus switching spikes.

Best regards,

  • 0
    TI__Mastermind 45390 points

    Nobuo,

    You can find I2C switches for automotive applications using the ti.com switch selection tool.  There are filters for features: supports I2C signals and Rating: automotive. 

    Like all passive FET switches the SN74LVC2G66 can support any protocol like I2C as long as the voltage and bandwidth of the protocol are within the recommended operating conditions of the device. 

    Do you have example of the bus spikes that are concerned about in the past? 

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Expert 8605 points

    Hi Adam,

    Thanks for your reply.

    I built simulation model with TINA-TI, but it looks spikes existing on I2C bus as shown in attached file.

    Perhaps it's due to simply simulation model but left as concern, but could you check if there is no concern for spikes in actual use case?

    It's more preferable if your team could provide actual measurement results like as wave form with same I2C bus selector configuration.

    Thanks and best regards,I2C scem573.TSC

  • 0 in reply to NOBUO FUJIHARA
    TI__Mastermind 45390 points

    Nobuo,

    The models are simplified versions of device behavior created based off the parameters in the datasheet and I'm not sure why it is causing the spikes. 

    I went into the lab and placed a 400kHz clock signal on A pin of the SN74LVC2G66 device, with Vcc = 3.3 V, and connected the scope to B pin.  I toggled the logic control pin C high and low to turn on and off the switch.  The resulting waveforms are below.  

    C pin is logic High switch on

    C pin is logic low switch off

    I didn't see any spikes you see in simulation when passing to the B side when the switch was off.

    Thank you,

    Adam