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I have development board with LDO used for reducing input voltage to 3.3V.

LDO not bypased

I want to bypass that LDO. Can I simply interconnect input and output of LDO? What happen if I brings the same voltage to both input and output of LDO?

bypased LDO

In my case LDO is LP5907MFX (datasheet) but i prefer generic answer rather.

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  • \$\begingroup\$ Which specific regulator make/model/part number it is? \$\endgroup\$
    – Justme
    Dec 11, 2020 at 8:38
  • \$\begingroup\$ I would remove the regulator, but it will probably be OK to just short the input and output. If you have the chance to modify the layout, you could put a zero Ohm resistor in place. \$\endgroup\$
    – user57037
    Dec 11, 2020 at 8:45
  • \$\begingroup\$ You could fry stuff connected to the 3.3 volt line? \$\endgroup\$
    – Andy aka
    Dec 11, 2020 at 9:17

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Usually nothing happens so yes, you can just do that (short input and output).

What happens is that the internal feedback of the LDO notices that the output voltage is higher than what is should be (for example 5 V instead of 3.3 V) and that will cut off the regulation transistor. Which is OK because the current will come through the short that you added.

To be sure, include the datasheet of the regulator that you're using so that we can have a look and confirm that it will work as I explained above.

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  • \$\begingroup\$ Question was updated with datasheet. \$\endgroup\$
    – Misaz
    Dec 11, 2020 at 11:37

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