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TPS75003 EN pin

Randy Kelso
Prodigy 100 points
Other Parts Discussed in Thread: TPS75003

Hello,

I am having trouble with EN3 pin on TPS75003. According to the datasheet the minimum threshold to turn on the LDO at the EN3 pin is 1.14V. However, I have found multiple devices turn on at 0.90V. Is there an error in the datasheet?

Thank you.

Randy 

  • 0
    TI__Guru**** 191445 points

    I can't comment directly on TPS75003, but I can tell you it is typical to specify EN pins like digital inputs with guaranteed high level and low level with actual switching threshold somewhere in between.  It is not technically an error but it is somewhat misleading.

  • 0 in reply to JohnTucker
    Prodigy 100 points
    Thanks John, But the threshold I have observed is below the min threshold listed in the datasheet. And they don't list a guaranteed high level so I am not sure how to proceed choosing a pair of resistor values to create a voltage divider that will always be on when Vin = 5V and always be off when Vin is < 2 V.
  • 0 in reply to Randy Kelso
    TI__Guru**** 191445 points
    Like I said, it is (probably) spec'd like a digital pin. The minimum level is really the voltage where where it is guaranteed to be high, the actual threshold will always be below it. They are expecting that you will supply a digital-like control, 3.3 V to be on or 0 V to be off. I have seen this on many data sheet specifications. Maybe we can get the characterization data for the actual threshold. Usually it will be around 0.8 to 1.1 V with about 100 mV of hysteresis. I don't directly support this part, but I have looked at a lot of these specifications over the last few years.
  • 0 in reply to JohnTucker
    Prodigy 100 points
    Sorry, John, that makes slightly more sense. I was thinking the threshold was the minimum min voltage to be on. You are saying it is the maximum min voltage to be on? I would like to know then what the highest voltage that pin is guaranteed to be off.
  • 0 in reply to Randy Kelso
    TI__Guru**** 191445 points
    The highest EN voltage where the TPS75003 is guaranteed to be off is 0.3 V. The lowest voltage where it is guaranteed to be on is 1.14 V. It will actually most likely be off at a much higher voltage than 0.3 V, but not guaranteed.