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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
I need a very stable voltage source. I can set it between 4.1-5.1v as long as it stays at one value with the smallest ripple possible. Right now I have a 7.5v wall adapter that I input into a 5.1v voltage regulator. On a standard volt meter the signal is stable. I will look at it with my digital scope later and see if putting a diode/capacitor or resistor/zenor combination help.
I am looking for advice as to the best way for the most stable voltage output for a precision instrument. Thanks.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
A 5.1 v zener diode has a significant dv/dT characteristic ... not what you want look for "precision reference" from your supplier.
You may find that the precision that you require is unavailable at your required voltage but precision resistor dividers can provide any lower reference voltage.
Registered Member #3943
Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552
How about a TL431? They are very stable and used in SMPS all the time to as a stable adjustable reference to set the output voltage. It is available in a number of different packages including the familiar TO-92 package.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Dr. Slack wrote ...
Use reasonably low noise amplifiers like OP275 (6nV), not LM324 or TL071, or any low current CMOS stuff.
I will look into this. How would I find a "low-noise" opamp using a datasheet. Is there a particular parameter during the search to fine tune this requirement?
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Having looked at the datasheet for the MAX6126B as suggested by PM the 4.096 V should be ideal as a reference for Lithium battery charge/discharge management. In my opinion, a super-precise reference is not required as the nominal 4.1 v charging voltage is a fairly loose specification, with for example no temperature considerations. (ask Boeing ! )
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precision voltage source
