LM317HV: dynamically adjust the output voltage with a DAC, is this possible?

Jorge Tornero

Part Number: LM317HV

Tool/software:

I need to get a regulated dc voltage but it will have different values depending on a digital setting. For this I had thought about using a DAC. In the case of a switched regulator it is easy to put the output of the DAC through a resistor to the FB pin but in the case of the LM317HV it is not so trivial. Is there any application note on this?

thank you,

Jorge

2 months ago

0 Nick Butts 2 months ago

TI__Mastermind 48045 points

Hi Jorge,

We have this content: (+) Give your voltage regulator the margin it deserves - Precision Hub - Archives - TI E2E support forums

I think the LM317HV should work similarly, except that since the LM317HV regulates the voltage across the top feedback resistor instead of the bottom resistor as it is in modern devices, the relationship between the DAC code and output voltage trend will be opposite of the case described in that post - if the DAC code is increased, the LDO output is raised instead of reduced.

Regards,

Nick

0 Jorge Tornero 1 month ago in reply to Nick Butts

Prodigy 110 points

thanks nick,

just what i needed to know and see in some explanatory note but just as you say with the difference of the points where Vref is located.

I will do the calculations to see if something feasible comes out of it.

thanks a lot.

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LM317HV: dynamically adjust the output voltage with a DAC, is this possible?