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TS5A3166: Does it have "powered off isolation" feature?

user4734074
Prodigy 130 points
Part Number: TS5A3166
Other Parts Discussed in Thread: TS5A3167

Hi,

Does TS5A3166 have Powered of isolation feature at Vcc=0V?

The history of the datasheet says,

Changes from Revision A (October 2012) to Revision B Page
• Removed 'Isolation in Powered-Off Mode, V+ = 0' bullet from Features

But the features of the web site are "Powered off protection, Break-before-make".

I want the TS5A3167 equivalent features with NO control logic.

Regards,

Tark

  • 0
    TI__Mastermind 45350 points

    Tark,

    The TS5A3166 has the powered off protection feature because you can see the Hi-Z when Vcc = 0V in the electrical specifications table.  I do not know why the revision history removed the "Isolation in powered-off mode, V+ =0V" maybe it is part of a branding effort to call the feature powered off protection.  

    Normally Open NO control logic isn't a good description for solid state switches because there are not any moving parts and every pin is always connected.  A better description is the signal path is ON or low impedance when control logic is set "XX" or OFF/Hi-Z when control logic is set "XX".  A logic low on the TS5A3167 will set the signal path Hi-Z but for the TS5A3166 a logic low will turn the signal path on and create a low impedance path.  

    For more information on powered off protection you can see this e2e posting. 

    Thank you, 

    Adam 

  • 0 in reply to Adam Torma
    Prodigy 130 points
    Thanks Adam for your answer and additional comment. I'm happy to know 3166 has the feature.
    Tark
  • 0 in reply to Adam Torma
    TI__Prodigy 510 points

    Hello Adam,

    In VNO = 3.3V and V+ = 0V condition, isn't it beyond absolute maximum condition of TS5A3166?

    Regards,

    Sam

  • 0 in reply to Sam Kim
    TI__Mastermind 45350 points

    Sam,

    Thank you for bringing this up.   I agree that the abs max spec and the powered off leakage spec contradict each other.  One of them I predict is a copy paste error from another datasheet.  I will order some devices and some hardware to see which one is correct.  I should have an answer next week and will update the datasheet.

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Mastermind 45350 points

    Sam,

    I tested the TS5A3166 and found out the powered off leakage spec is valid. I placed 5V on the signal path with Vcc = 0V and the signal did not pass through the switch.

    However, when I had Vcc = floating and 5V on the signal path the 5V signal still passed through the switch.

    This tells me this device does not have a very robust powered off protection. It only has protection in the case where Vcc =0V and then a voltage is applied on the signal path. I think this is why they removed the feature from the datasheet because it only has protection when Vcc = 0V.

    Thank you,
    Adam

  • 0 in reply to Adam Torma
    TI__Prodigy 510 points

    Adam,

    For clarification, the VCC should be grounded to support power-off protection feature. And it won't isolate the path when VCC is left floating.

    Regards,

    Sam

  • 0 in reply to Sam Kim
    TI__Mastermind 45350 points

    Sam,

    The signal path is Hi-Z when Vcc = 0V as stated in the signal leakage spec when Vcc = 0V.

    There is a case I noticed where the signal path was not isolated. 

    1) Vcc = a valid voltage

    2) there is a voltage present on the signal path

    3) Then Vcc goes floating

    In this case, the voltage that was on the signal path appears to keep the gate of the FET charged because Vcc is floating and doesn't turn off the FET. 

    This is not an issue if Vcc = 0 V

    I would say you need to ground Vcc to prevent the gate of the FET to be back powered by a voltage on the signal path. 

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Prodigy 510 points
    Thanks for your clarification.

    Regards,
    Sam