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How to adjust the output voltage of LT1761 (LDO) to 2 Volts?

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Hello Guys
I have a project in which i need to use a LDO (low drop out regulator) with output fixed to 2v, i found LT1761 from linear technology which seems to be suitable, I need also to simulate the cicuit to check its functionality, I have also found its pspice model and successfully created the component in orcad, I have to say that such IC is available with 2v fixed output and also with adjustable output, the model i have is for the adjustable output, i read the data sheet to figure out how to adjust the output to be 2v and found a figure and couple of notes but unfortunately the equations seem to provide unpredicted results, may someone help me with this please
Datasheet is attached

Also to simplify the matter, I need any LDO with output voltage fixed to 2 volt
you can suggest any but with Pspice model, otherwise the one i have is fine and in that case may someone help me please
Thanks in advance
 

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  • LT1761.pdf
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Vadj is 1.22V. So you need to arrange R2 and R1 so that you have 1.22V at the ADJ pin when you have 2.0V on OUT.

The resistors need to be small enough to allow at least 30nA into the ADJ pin, but otherwise there is little restriction. If the resistors are small you can ignore Iadj.

Rearranging the Vout equation you get Vout - 1.22 = 1.22(R2/R1), so for 2.0V, 0.78 = 1.22(R2/R1), so 0.64= R2/R1. Chosing some value for R2 like 10k gets 0.64R1= 10,000, or R1=10,000/0.64 = 15625, or around 15k.

You can verify that at voltage divider with 10k at the top and 15k at the bottom is gives around 1.2V with 2V at the top. For greater accuracy you can make R1 out of two resistors (15k + 620R for instance)......
 

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