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TPS61230: Oscillation on Vin

Part Number: TPS61230

When the power down slew rate is extremely slow (ex: 3.3V -> 2V takes 10ms), it will result in an “oscillation” (or “power ring”).

For instance:

Input power droop below 2.5V -> All the circuits connect to the 61230’s output will be power off -> Input power will goes up slightly since it becomes “light load” at the moment -> Circuit sink current from 61230’s output since its power is back -> Input power droop below 2.5V

 

Is there any way to modify TPS61230’s peripheral to eliminate this issue?

 

 “power ring” image(The blue line, which is TPS61230, VIN pin voltage) in below mail.

  • Hi 

    this device has a HYS pin to configure the UVLO voltage. you can try this function.

    but does this behavior impact customer's system?

  • Hi Jasper 

    I just realized that the pin out is different between TPS61230 and TPS61230A.

    The issue we observed is actually on TPS61230A which don't have HYS pin.

    Sorry for the wrong IC#.

    Could you please advise if there is any other way to make adjustment on TPS61230A.

    Thanks!

  • Hi,

    unfortunately, there is no method to adjust the UVLO hysteresis of the TPS61230A. How does such behavior impact the system? must we eliminate such behavior? 

  • Hi Jasper
    Our customer (host system) is testing the power down with extremely slow rate. We connect the EN to the input via a 10K resistor directly. When the power down rate is slow (ex: 3.3 --> 2.5V: 5ms), it's very likely to cause a power ring (or oscillation) not only in the 61230a input but output as well. The up&down voltage will cause a series mul-functioning of the back-end circuit.
  • Hi Sam,

    as the startup and shutdown of TPS61230A is only determined by the IC internal circuit. there is not simple solution to solve the issue.

    the solution could be

    1. reduce the impedance of power supply and increase the input capacitor to reduce the voltage ringing in VIN

    2. disable the IC through EN pin using a voltage monitor IC or the MCU in the system.