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TCA9544A: VPass and VCC (VGate) Test Waveform

Ting Ye
Genius 11800 points
Part Number: TCA9544A


Hello Team,

I happened to do test for TCA9544A and captured waveform when VCC is larger than specified gate voltage (page 7 and 8). Could you help let me know if page 7 and 8 reflect the behavior when VCC (Vgate) and VBUS (Vpass) violates? Thank you.TCA9544A VCC and VBUS Test_201805.pdf

Regards,

Ting

  • 0
    TI__Guru 62920 points
    Hi Ting,

    Yes, this may be due to too low of a gate voltage (caused by too low of a VCC). It is hard to tell for sure, though. You are right that when the voltage is too low it causes the switch to not properly behave as a high impedance for high-level signals, and so you can get some current flow from the higher-voltage side to the lower-voltage side. This usually causes an increase in the lower voltage, which looks to be the case on SCL0 of slide 8. The behavior depends a bit on how the power rails are designed, though, and how they react to sinking current.

    Max