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Can one LDO perform two output?

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sj95

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Hi All:

I have a LDO with resistor divider to adjust the output.
I need the LDO output 3.3V for a while than change output to 1.8V.

How to perform that?

I use a switch to change the resistor divider , but the output voltage has a droop before it goes to 1.8v, it is not smooth to the system...

Thank you very much.
 

kak111

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Without knowing exactly your circuit i guess that..................

If you use normal mechanical changeover switch
remember that switch is open few milliseconds when you change position.
(= ref. signal = ??? at that time )

Make your connection so that switch add new resistor to voltage divider.
(Parallel to groundside resistor)

You can also test the effect of capacitor from Vref. to ground ( 1...10microfarads)

Regards KAK
 
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umesh49

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It will happen due to bulk capacitor at the output of regulator. You might need to find a way to dischrage the capacitor before going to switch from 3.3V to 1.8V.

Umesh.
 

leo_o2

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Try to switch voltage reference of LDO instead of feedback resistor ratio.
 

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