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TPS7A03: Leakage current when Vin < Ven

Mike Ciholas
Prodigy 140 points
Part Number: TPS7A03
Other Parts Discussed in Thread: TLV733P, , TPS7A02

The TPS7A0333 datasheet gives a leakage current of 10 nA typical for EN when Vin = Ven = 6 volts.

What should I expect for leakage current if Vin = 0 or is floating and Ven is 1.8 volts?

My design uses the TPS7A0333 for a USB regulator and the USB connection will not always be present, but I must have the 3.3 volts come on after the 1.8 volts for sequencing.  The simplest approach is to tie the EN pin to 1.8 volts so the 3.3 volts is assured to com eon afterward, but sometimes Vin will be missing while Ven is 1.8 volts.  My hope is the leakage of Ven is not related to Vin.

Thanks.

  • 0
    Prodigy 140 points

    To follow up, I think the primary issue is the :smart pull down" feature and how it behaves when Vin is 0 or floating, and EN pin is pulled high, say to 1.8 volts.  The diagram in the DS seems to imply the smart pull down requires Vin to drive an NFET to activate, so if Vin is missing, the smart pull down can't work.

    This issue affects my design since I need very low leakage on EN when Vin is 0 or absent otherwise it will affect my battery life negatively.

    Some devices have a warning about EN being higher than Vin (TLV733P for example) but the TPS7A0333 lacks any such indication in the DS.  Does that mean the TPS7A0333 is different or that the DS has an oversight?

  • 0 in reply to Mike Ciholas
    TI__Mastermind 47335 points

    Hi Mike,

    Firstly, have you looked at TPS7A02 instead of TPS7A03? It has a much better ground current spec if low power consumption is important for your application. 

    I don't know for sure about your question because it will depend on the device architecture. Some devices have no extra leakage in this scenario but some do. I'm going to try getting a test bench set up with the original design and see if I can see any difference. I think you are correct though in that VIN needs to be supplied for the EN pulldown to work, so this might be fine. 

    I'll update you when I have information to share. FYI, I'm OoO the second half of this week so please bare with me if I can't get results before I'm out. 

    Regards,

    Nick

  • 0 in reply to Nick Butts
    Prodigy 140 points
    Nick Butts said:
    have you looked at TPS7A02 instead of TPS7A03? It has a much better ground current spec if low power consumption is important for your application. 

    TPS7A02 price is higher, not worth the cost for < 200 nA Iq difference.  My application is cost sensitive.

    I will await your measurements on EN current when Vin 0 or missing.  Thanks.

  • 0 in reply to Mike Ciholas
    TI__Genius 12511 points

    Hi Mike,

    Thank you for your patience Nick will get back to you as soon as he is able to take the EN pin measurements in our lab.

  • 0 in reply to Mike Ciholas
    TI__Mastermind 47335 points

    Hi Mike,

    Sorry, but I am having issues getting a test bench set up. I'm also leaving for a short vacation today and will return Monday and I don't have the time to get to it today. I'll get back to it on Monday. 

    Regards,

    Nick

  • 0 in reply to Mike Ciholas
    TI__Mastermind 47335 points

    Hi Mike,

    Very sorry for the delay. I had forgotten to get back to you when I got back from vacation. I won't have time to work on this until next week and it's a holiday, so I am going to try getting the measurements done by the end of next week.

    Regards,

    Nick