Regulator LD1085V Question

Captn Dave · 16th September 2009, 05:24 PM

The data sheet (page 4) for the LD1085 gives the following equation for calculating resistance for the resistor that sets the Output voltage:

Vo=Vref (1-(R2/R1))

Simple enough.

What's Vref???

I know it's something embarasingly obvious but I can't see it.

Thanks

Gordy · 16th September 2009, 05:31 PM

For most regulators it is 1.25V.
I am surprised that they omitted such information from the datasheet.

Nisbeth · 16th September 2009, 05:37 PM

You're right that isn't actually in the datasheet

It is 1.25V though (look at the DS for the LT1085 or even the LM317 to find the specs.)

/U.

Captn Dave · 16th September 2009, 08:18 PM

Thanks guys. I knew that was true of the LM317 but I didn't think it necessarily followed that it would be true of this regulator. I appreciate the help.

16th September 2009, 05:24 PM	#1
Captn Dave diyAudio Member Join Date: Jun 2008	Regulator LD1085V Question The data sheet (page 4) for the LD1085 gives the following equation for calculating resistance for the resistor that sets the Output voltage: Vo=Vref (1-(R2/R1)) Simple enough. What's Vref??? I know it's something embarasingly obvious but I can't see it. Thanks

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16th September 2009, 05:31 PM	#2
Gordy diyAudio Member Join Date: Nov 2006	For most regulators it is 1.25V. I am surprised that they omitted such information from the datasheet.

16th September 2009, 05:37 PM	#3
Nisbeth diyAudio Member Join Date: Jan 2001 Location: Denmark	You're right that isn't actually in the datasheet It is 1.25V though (look at the DS for the LT1085 or even the LM317 to find the specs.) /U.

16th September 2009, 08:18 PM	#4
Captn Dave diyAudio Member Join Date: Jun 2008	Thanks guys. I knew that was true of the LM317 but I didn't think it necessarily followed that it would be true of this regulator. I appreciate the help.

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