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TCA9548A: TCA9548A

Dhilipkumar M
Prodigy 20 points
Part Number: TCA9548A
We are using the I2C mux (TCA9548ARGER) chip in one of the Telecom products. 
Currently, we are in testing phase of the Proto build, and we are using failure in the I2C mux chip during power up condition due to high transient noise.
 
 we faced I2C mux IC failures due to transient noise and it shows low impedance in the SCL and SDA lines.
Power up condition:
  • Slave 1( Power supply module) is powered first from 5V and SDA,SCL  shall powered with bias voltage of 3.3V ( derived from 5V internally) , but the power rail of VCC(1.8V) and IO voltage (3.3V)of TCA9548ARGER will be powered in after 48ms. Please find the below image for the circuit implementation
Query:
  1. Is this failure observed due to the power sequencing?
  2. Please provide the TI recommendation to mitigate this problem.
 Below are our thoughts to mitigate this issue
  1. Adding I2C buffer/isolator in SCL and SDA, if this solution works, please suggest part number for the same
  2. Adding Ferrite bead in series ( both SCL and SDA)
Please share your thoughts.
Regards,
Dhilipkumar.M
  • 0
    TI__Mastermind 49250 points

    Hello Dhilipkumar,

    Our TCA9548A device doesn't have any specific power sequencing requirement so I don't think this is the root cause here. The device stays at a HI-Z state between the main SDA/SCL line and the secondary channels when Vcc is not present.

    "we faced I2C mux IC failures due to transient noise and it shows low impedance in the SCL and SDA lines."

    You mean that the SDA/SCL lines of the TCA9548A appear to be shorted to GND or each other due to damage to the device?

    Does the downstream device also see any damage?

    Would you happen to have a scopeshot of what the transient noise looks like? 

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 20 points

    Hi Bobby,

    Thanks for the response.

    we suspect due to transient noise the IC got failure, since the IC is not powered but the Slave 1 is biased with 3.3V

    Thanks,

    Dhilip

  • 0 in reply to Dhilipkumar M
    TI__Mastermind 49250 points

    Can you send a scopeshot of what the transient looks like? It's hard for me to provide a solution/suggestion without knowing what the suspected damaging signal looks like (undershoot/overshoot levels)

    -Bobby