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help with this regulator: LT3080

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strokedmaro

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I'm going to be playing with this regulator for a project. I'm looking to parallel 2 of these as discribed on page 10 (Fig 4)...The goal is to be able to input 12-16vdc and go as low as .2 vdc The only thing I cant seem to find in the data sheet is the set pin resistance to output vdc information. I understand that I could just attach a trimmer to the set pin and adjust the voltage that way but If I was looking for a specific output, how would I figure that out?

BTW Ive ordered the SOT-223 version which should work perfectly in the parallel example as the Vcontrol and in are already tied.

Thanks!
 

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I think it is simple math. In the example on page 10 the output is 3.3V. The resistor from the set pin to ground is 165K. So 3.3/165K=20µA. So if you know the voltage you want, divide the voltage by 20µA. Keep in mind each regulator needs the 10µA and there is some room for error as on page 3 Iset has some variables.
 
Just curious as to why the schematic on paralleling on page 10 does not include the additional 10uF capacitor?? could it be a single 20uF instead?
 
Just curious as to why the schematic on paralleling on page 10 does not include the additional 10uF capacitor?? could it be a single 20uF instead?
I don't know which 10µF capacitor you are talking about, but on page 10 of the data sheet I see a 10µF capacitor on the output. Page 9 has info about the output capacitor. There are a number of factors that affect the output capacitance so changing to 20µF may be necessary.
 
I see just one 10µA connected to both regulators outputs on page 10... I was asking whether or not EACH of them need their own as you posted
The SET current on each device is 10uA. The SET pins are connected in parallel, so 20uA flows through the programming resistor (165k in the schematic).
Vout =20uA*Rprog.
 
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