# Voltage reference question

#### Dsmith5282

Joined Jan 20, 2017
3
Afternoon people, I'm new to electronics and have a question about voltage reference. What is it and how is it used?
Thanks for any help.

#### paulktreg

Joined Jun 2, 2008
836

#12

#### #12

Joined Nov 30, 2010
18,224
A voltage reference is supposed to be stable during changes in time and temperature. It is used as a standard by which to measure other voltages. This comparison might be as vague as building a complicated circuit and having several points in that circuit, directly or indirectly, related to the voltage reference.

#### OBW0549

Joined Mar 2, 2015
3,566
A voltage reference is a specialized form of voltage regulator that's optimized for high accuracy and good stability against line and load variations and against temperature. Unlike a normal voltage regulator, they usually cannot put out very much current, and are mainly used to provide a highly accurate reference input to analog-to-digital converters. Here's the data sheet for one such voltage reference so you can get an idea of its performance.

#12

#### Dsmith5282

Joined Jan 20, 2017
3
I understand the concept but what does adc use the reference for?

#### #12

Joined Nov 30, 2010
18,224
I understand the concept but what does adc use the reference for?
An ADC, by definition, measures voltage. The ADC needs to know what a volt is. The voltage reference tells the ADC exactly what a volt is so the input to be measured can be compared to the standard.

#### crutschow

Joined Mar 14, 2008
34,680
I understand the concept but what does adc use the reference for?
The ADC converts an analog voltage to a digital word representing that voltage, by comparing the analog voltage to the reference voltage.
The accuracy of the conversion (i.e. how accurately that words represents the actual voltage) depends largely on the accuracy of the reference voltage.

#### Dsmith5282

Joined Jan 20, 2017
3
Oh I see now, thank you very much

#### #12

Joined Nov 30, 2010
18,224
I understand the concept but what does adc use the reference for?
It teaches us to name the application so we don't get nebulous answers to a nebulous question and end up with nothing useful.

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#### OBW0549

Joined Mar 2, 2015
3,566
I understand the concept but what does adc use the reference for?
The basis of operation of nearly all A/D converters is that they are ratiometric; that is, they generate an answer (i.e., the digital conversion result) in the form of a binary fraction between 0 and 1 equal to the input voltage divided by the reference voltage. The more accurate the reference voltage is, the more accurate the conversion result will be.

#12

#### hp1729

Joined Nov 23, 2015
2,304
Afternoon people, I'm new to electronics and have a question about voltage reference. What is it and how is it used?
Thanks for any help.
Anywhere you need a predictable and stable voltage. Voltage regulators for instance. You needto compare an unpredictable voltage to a known voltage.