• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 417 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS2116: Question about the behavior in priority mode

Go
Genius 4220 points
Part Number: TPS2116

HI,

Let me ask the expected behavior that TPS2116 is set to priority mode as below.

In case that input supply 2 is applied to TPS2116 first when in the initial state (means, both input supply 1 and 2 are absent) ,

Will VOUT output VIN2? or input supply 1 must be applied first to TPS2116 in priority mode?

Regards,

Go

  • 0
    TI__Genius 16085 points

    Hello, 

    A loss or lack of supply will supersede any established prioity/manual mode configuration. 

    To clarify, regardless of the MODE pin voltage, if one of the voltage supplies drops below 1.6V, the device will select the other supply to power the output as long as it too is not <1.6V. If both supplies are invalid (VINx<1.6V), the device will output a high impedance. 

    The first supply VIN1 does not need to be applied first for the device to select VIN2. 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Genius 4220 points

    Hi, Elizabeth,

    Thank you for your comment.

    I did some start-up simulation with  TPS2116 PSpice Unencrypted Transient Model (Rev. A) on PSpice for TI.

    As see in the waveform below, I changed start up sequence that VIN2 ramped up first.

    I thought VOUT should output VIN2 in this case as you mentioned before, "The first supply VIN1 does not need to be applied first for the device to select VIN2", but the simulation result showed VIN2 aren't seemed to be selected.

    Is it an unexpected behavior due to the simulation model? or do we actually need to apply VIN1 first?

    And is it possible for you to see the behavior on EVM if VIN2 is applied first when start-up?

    Sincerely,

    Go

  • 0 in reply to Go
    TI__Genius 16085 points

    Hi Go, 

    Yes this is unexpected behavior from the simulation model. There is no dependence on IN1 assertion for the device to select IN2 as the output. 

    The TPS2116 uses the highest voltage supply to power the internals of the device. When one supply drops below the other, the device changes the supply used to power the device so you do not need to apply VIN1 first. 

    Below is a scopeshot using the TPS2116EVM showing VIN1 is not needed for VIN2 to be selected as the output: 

    Best Regards, 

    Elizabeth