Voltage controlled regulator

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edaenrico

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Hi,

I have to design a voltage regulator where the output voltage is controlled by an external analog voltage.

The output voltage of the regulator range: 0-12 Volt

The control voltage range: 0-3.3 Volt


I tried with an LM317 without success

Thanks,
Enrico Migliore
 

I would recommend, if you can stand a fairly poor frequency
response and have the headroom (you do not say about the
input voltage range, which is a key design parameter) a
single supply op amp driving the gate of a PMOSFET (if
VIN > 8V) or maybe a NPN Darlington (if you have an AUX
supply but VIN is lower) or NMOSFET (if AUX > 8V and
VINmin can be close to VOUTmax). Your output current
would be important to component selection as well.
 

Hi,

You can use almost any adjustable regulator, that work with a resistive divider from output to FB pin.
Just connect an extra resistor from your control voltage to the FB pin.

Then the output voltage is high when control voltage is low.

Klaus
 

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