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TPS2115: Autoswitching mode and hysteresis

Alberto Sanchez
Prodigy 20 points
Part Number: TPS2115
Other Parts Discussed in Thread: TPS2113A, , TPS2116

Hello!!

I am having trobles with the Hysteresis in this circuit.

A ripple in the inputs makes the output switch permanet the inputs.

I am thinking of adding an external comparator.

Can you give me any advise or idea??

  • 0
    Prodigy 20 points

    P.D. I want to give priority to the IN1

  • +1 in reply to Alberto Sanchez
    TI__Mastermind 32650 points

    Hi Alberto,

    The setup you have right now is a direct comparison of IN1 and IN2. Since they are similar voltages, any ripple here could result in switching.

    I think you have a few options here:

    1. Try switching the D1 and D0 pins. If D0 is GND, the D1 will dictate if the OUT is IN1 or IN2.

    2. Use TPS2113A. This device is similar to TPS2115A and in the same package and has similar pins. The major difference is that is is built for the situation described in 1. and has a tighter tolerance for the voltages resulting in less time when Dx pins have an voltage which is in between V_il and V_ih.

    3. Use TPS2116. TPS2116 is a new generation low Iq powerMUX. It can be used to set priority and a user set hysteresis window is also possible. Finally, this device can handle more current and switches faster than older TPS211xA devices.

    Thanks,

    Shreyas

  • +1 in reply to Shreyas Dmello
    Prodigy 20 points

    Thank you so much, Shreyas!

  • 0 in reply to Shreyas Dmello
    Prodigy 20 points

    THe MUX is switching at 2.5kHz. I am not sure if is a high frecuency to the normal operation.

  • 0 in reply to Alberto Sanchez
    TI__Mastermind 32650 points

    Hi Alberto,

    The device is meant to work in DC only. By switching at 2.5kHz do you mean that it switches between the inputs at 2.5kHz? This is not stable operation of the device as it is meant to switch to one input and hold it there. All timing characteristics can be found on the datasheet.

    If you are seeing the device turn off and on again, please make sure you are not hitting thermal shutdown by way of current limit.

    Thanks,

    Shreyas