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TPS74401: EN pin voltage when VOUT starts rising

Masahito Takei
Intellectual 290 points
Part Number: TPS74401
Other Parts Discussed in Thread: TUSB7320

Hi team,

The datasheet states that the minimum high voltage for the EN pin is 1.1V.

On the other hand, I think the voltage on the EN pin will be less than 1.1V when VOUT starts to rise.

Could you please tell me the minimum voltage specification for the EN pin when VOUT starts rising?

Regards,

Masahito

  • 0
    TI__Expert 5510 points

    Hi Takei-san,

    1.1V is the minimum voltage on the EN pin to ensure consistent enable behavior of the LDO. There is a voltage range 0.4V<VEN<1.1V where enable behavior is not defined, and if a voltage within this range is supplied to the EN pin, the LDO may be either enabled or disabled, or toggle between enabled and disabled.

    Therefore, it is recommended that 1.1V minimum be provided at EN to enable the device, and VEN<0.4V to disable the device.

    Regards,

    Kelsey

  • 0 in reply to Kelsey Farr
    Intellectual 290 points

    Hi Kelsey,

    Thank you for your reply.
    I understood that there is a voltage range 0.4V<V EN <1.1V for which the enable operation is not defined. For reference, could you please tell me some actual voltages at which it switches from disabled to enabled?

    Below is an excerpt from the TUSB7320 data sheet (page.28). I asked this question because I connect a capacitor and a resistor to the EN pin and want to know when the VOUT output starts rising when there is a time constant.

    Regards,

    Masahito

  • +1 in reply to Masahito Takei
    TI__Expert 5510 points

    Hi Takei-san,

    Thanks for the clarification. I can give some example values to characterize enable threshold when Vout starts to rise, but for values VEN<1.1V, since this is not a spec'd parameter, actual behavior may vary. So while I can provide you with some benchmark voltages, these should be taken as rough estimates only, as enable threshold voltage can vary across temperature especially.

    From the data we have available:

    -40C: VEN=0.807V

    25C: VEN=0.794V

    125C: VEN=0.690V

    Regards,

    Kelsey