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TCA9617B: VCCA ≤ VCCB is required during power-up/down sequence?

Noriyuki Takahashi
Genius 11900 points

Part Number: TCA9617B
Other Parts Discussed in Thread: TCA9509, TCA9617A

Hi team,

VCCA ≤ VCCB is required in TCA9617B. However, is this also required during power-up/down sequence?

In case of TCA9509,  VCCA ≤ (VCCB – 1 V) is also required. Is this required during power-up/down sequence?

Regards,

Noriyuki Takahashi

  • 0
    TI__Mastermind 26836 points

    Takahashi-san,

    The requirement you pointed out is needed for proper translation operation, but I imagine that you will not be communicating while VCCB is unpowered. If you are asking whether this is expected to damage the device, then it should not. As long as you keep the device within its Absolute Maximum Ratings in section 6.1 of the TCA9614B datasheet and section 7.1 of the TCA9509 datasheet, then the device should not be damaged.

    You might see some current flow across the device if the supply conditions are not met. Is this happening very quickly for a short time, or is this a condition that would be sustained and/or repeated in application?

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Genius 11900 points

    Danny,

    Sorry. I misunderstood customer's questions. Following are correct questions.

    Regarding TCA9617A & TCA9617B, VCCA should be less than VCCB? Is it OK that VCCB is higher than VCCA?

    Regarding TCA9617A & TCA9617B, are there any power-up sequence required?

    Regards,

    Noriyuki Takahashi

  • 0 in reply to Noriyuki Takahashi
    TI__Mastermind 26836 points

    Takahashi-san,

    Of course, don't worry!

    Noriyuki Takahashi said:

    Regarding TCA9617A & TCA9617B, VCCA should be less than VCCB? Is it OK that VCCB is higher than VCCA?

    Yes, it is recommended design to have VCCB higher than VCCA. Note in 6.3 Recomended Operating Conditions that the maximum recommended voltage of VCCA is VCCB.

    Noriyuki Takahashi said:

    Regarding TCA9617A & TCA9617B, are there any power-up sequence required?

    There are not power ramp requirements for this device. It does not have any internal registers, so there is no issue of initialization for it.

    Best,

    Danny