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REF2033: Output behavior when EN = 0

Dominic Ryan87
Prodigy 170 points
Part Number: REF2033

Hi,

In the datasheet for this device there is the following statement:

"The REF20xx can be placed in a low-power mode by pulling the ENABLE pin low. When in shutdown mode, the output of the device becomes high impedance and the quiescent current of the device reduces to 5 µA in shutdown mode."

When I tested two separate units in a circuit where there is a 56 ohm load from Vin of 3.6V to Vref, pulling EN low results in the Vref output sitting around 1.35V, which suggests it is sinking ~40mA / acting as a ~33ohm load.  Although the datasheet doesn't appear to specify what "high impedance" means numerically this result surprised me.  Am I missing something?

Thanks

  • 0
    Prodigy 170 points

    I should also mention this appears to happen both when the device is disabled after booting with EN tied high (or floating), as well as when the device is powered up with EN low.

  • 0 in reply to Dominic Ryan87
    TI__Genius 11391 points

    Hi Dominic 

    Can you please explain why you are are shorting input and output with 56ohm resistor?  Is it your regular use case. I am asking this because this is not a regular use case. It may trigger some of the internal circuit and that's why you are seeing high current. 

    Regards

    Trailokya

  • 0 in reply to Trailokya Rai
    Prodigy 170 points

    I am pre-loading the output to shift the output current range a bit.  I totally understand that is not a normal use case, I just wanted to see if the behavior was unexpected since the output was listed as high impedance.

  • +1 in reply to Dominic Ryan87
    TI__Genius 11391 points

    Hi Dominic

    Thanks for your clarification. 

    Forcing higher than VREF voltage may cause unexpected behavior in REF20. 

    Regards

    Trailokya