Anyone can suggest a very precise and constant 5V reference? I Google and see many are recommend LT1085 and LM317? Which one is better? Any better recommendation?

 

The LM317 and LT1085 are adjustable voltage regulators, they would only be as accurate as the resistor (1% max, typ 20%)

LT1027 is a Precision 5V Reference for +- 1/1000th volt. It will only supply 35 mA, however.

If you are looking for a power supply type 5 Volt Regulator, the 75L05 will work for low current projects.

For higher current projects/circuits, would need to know use and current draw required.

 

Hi,
Those two are adjustable regulators not references. If you want something very common and widely used, you can make it with a TL431.
But, dedicated chips are RH1021-5, LT1027, MAX675, REF02, REF05, etc.

Hope this helps.
Tahmid.

 

Calibrated, off the shelf reference chips with stellar performance and a range of voltages are available from Digikey and others in the form of the LM4040 series devices.

See: http://tinyurl.com/375ufnq

These are simply precision zener diodes factory trimmed to very tight tolerances. Even the highest performing devices are only a few dollars.

 

LT6656 - precision +/-0.05%
TL431B - precision +/- 0.5% (requires precision resistors as well.)