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LDO with Linear output voltage control

Kai Nomiyama
Expert 5275 points

Hi Team,

I'm looking for the solution that meets below.

- Input voltage: 10~15V

- Output voltage: changed 2~5V as linear

- Output current: less than 100mA

This is my idea but if we use LDO having adjustable output with potentiometer for feedback resistor can be used as the solution if the internal Error amp can responce.

What do you think is it ok for LDO?

In addition, if you know the devices that meet above requirements, could you let me know?

Thanks,

Regards,

Kai

  • 0
    TI__Guru 55940 points
    Hi Kai,

    Yes your idea is a valid method of adjusting the output of any adjustable LDO. You will want to use the pot in place of the top resistor in the feedback network so that you can fix the resistor divider current for better accuracy. We typically recommend that the feedback resistor divider be ~100x the feedback current for the LDO. This is recommended so that the feedback current effect on the resistor divider becomes negligible. The feedback current and reference voltage should be specified in the Electrical Characteristics table. Dividing the reference voltage by 100x the feedback current will give you R2.

    Another method is to use a DAC to drive the FB node of the LDO. The following blog gives a basic introduction to the idea:
    e2e.ti.com/.../give-your-voltage-regulator-the-margin-it-deserves

    Very Respectfully,
    Ryan