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TPS737: when EN=0, there is still 2.4V on the output pin

michael gao
Prodigy 220 points
Part Number: TPS737

Dears:

My customer is using TPS73733(fixed output), when EN=0, it can't disable output, finally I found that the phenomenon disappears when cut the connection between TPS73733 and load, the load includes 2pcs SX1276, it is obvious that there is no problem with tps73733, I doubt there are too many decoupling capacitors in the load, but I am not sure about it, could you give me your suggestion? thanks

 

  • 0
    TI__Guru 55940 points
    Hi Michael,

    Since TPS737 does not have an active pulldown, it is up to the load to discharge the output capacitors when the LDO is disabled by Ven = 0 V. If the output rail is not dropping fast enough for your application, you could consider providing an external discharge path for the output such as a resistor to ground or an external active pulldown. An external active pulldown would consist of a FET and current limiting resistor from OUT to GND. The gate of the FET would be tied to EN of TPS737 so that the FET is ON when the LDO is OFF.

    It looks like you attempted to insert images that did not properly attach to the post. Please refer to the information here for how to properly attach images:

    e2e.ti.com/.../149.4-3-inserting-an-image-on-e2e

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 220 points
    Dear Ryan:
    Thanks for your great help and suggestion, I think I have gotten the answer that I need.