Variable ldo

I am looking for recommendations for variable LDO USB 5 V input and variable output voltage from 1.6 to 5.5 V. voltage range done by a variable resistor. With current draw up to 50mA.

A low drop out regulator, LDO, can’t increase the voltage or even match the input voltage.

To get 1.6 to 5.5 from a 4.75 to 5.25 (USB spec) input you can use a buck-boost switching regulator.

You could also use boost regulator to get the voltage up to say 7 volts followed by an adjustable linear LDO to get the final range.

Hi, thank you so much for your response. Kindly recommend a few part numbers

Take a look at Digikey part MCP1253-ADJI/MS-ND , this should get you started.

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Thank you so much for the recommendation.

Hi Steve,

I am trying to work with the component you recommended. I am a confused how to connect the pot I calculated. Kindly show me.

Thank you so much in advance.

Ephraim Ben-Ishai 4X5EG

You wire the potentiometer as a rheostat like this:

A potentiometer adjusts circuit voltage by varying the ratio of two resistances.
A rheostat adjusts circuit current by varying a single resistance.
All potentiometers can be wired as rheostats, dedicated rheostats are rarely usable as a potentiometer.

Your circuit uses a rheostat plus a fixed resistor to create a potentiometer that only adjusts in one direction. A very common application that greatly improves adjustability, stability and provides a low limit greater than the lowest voltage.


Thank you so much!

Ephraim Ben-Ishai 4X5EG