5V to 5V precision voltage reference

[prescott2006]

Is there any IC that can output a precision 5V from a 5V supply?

 

[ericgibbs]

Is there any IC that can output a precision 5V from a 5V supply?

I have never seen a single IC device that would do that, its possible to use a DC to DC step up IC, say to 9V and then use 5V reference IC.

 

[ronv]

How much current do you need?
What is precision? 1%, .5% etc.?
Is your normal supply over 5 Volts or under?

 

[crutschow]

Obviously you can not generate a precision 5V if the source voltage is slightly less than 5V. The source voltage must always be higher than the desired reference voltage. Commercial voltage references typically require a volt or more headroom to operate, but you could make a reference with a precision low voltage reference (1.2V to 3.3V), a precision rail-rail op amp, some precision resistors, and a logic-level PMOSFET transistor, that would regulate to within a few millivolts of the supply voltage, depending upon the required reference load current.

 

[MikeMl]

Chances are that the OP wants the reference for something like a uController ADC. You can always make say a 4V Vref out of 5V, and then just scale the ADC inputs from 0V to 4V instead of 0V to 5V.

 

[MrAl]

Hi,

Another idea is to use a shunt regulator in stead of a series type regulator. If the first regulator regulates to say -5 percent then that would mean 4.75v would be the highest voltage that you can get out of the shunt regulator in order for it to work for all possible pre-regulator outputs (which might vary from 4.75v to 5.25v about).

If that cant work out good enough since this is just for a voltage reference supply, you can also look into making a small low current boost circuit with just a couple capacitors. The circuit looks like a voltage doubler more or less.

If this still isnt quite good enough, since you only need to boost the voltage by maybe 0.5v to get this to work wth a shunt type regulator, you can use a more static method. Get a small solar cell and shine a white LED onto it's surface powering the LED from the badly regulated 5v supply, and have the solar cell connected in series with the badly regulated 5v supply. The output of the solar cell will be about 0.7v higher than the normal 5v supply which would be just enough. The output would be 5.7v nominal, but could sink as low as 5.2v with a change in the bad regulator output of -10 percent, but that would still be good enough to use a shunt type regulator with. The requirement here is that you have enough power to power the LED at a high enough current to get the solar cell to work properly. The shunt regulator could then be made to regulate the output to 5v at much higher precision and stability.