Maxim > Design Support > Technical Documents > Application Notes > A/D and D/A Conversion/Sampling Circuits > APP 2879
Maxim > Design Support > Technical Documents > Application Notes > Amplifiers > APP 2879
Maxim > Design Support > Technical Documents > Application Notes > Automotive > APP 2879
Keywords: zener references, bandgap, references, voltage reference selection
APPLICATION NOTE 2879
Selecting the Optimum Voltage Reference
Oct 17, 2013
Abstract:
What could
be more basic than a voltage reference—a simple, constant reference voltage? As
with all design topics, there are tradeoffs. This article discusses the different types of voltage references,
their key specifications, and the design tradeoffs, including accuracy, temperature-independence, current
drive capability, power dissipation, stability, noise, and cost.
You can find voltage references inside almost any advanced electronic product, either standalone or
integrated into larger functions. Understanding the technology as well as the system error budget is an
important design consideration. Because of limited space, we suggest further reading in the footnotes as
we touch on system concepts. For example:
1. In a voltage regulator, a reference provides a known value that is compared to the output to develop
the feedback used to regulate the output voltage
1
.
a. Remote voltage adjustment and power-supply margining may be needed in the application
2, 3,
4
.
2. In a data converter, a reference provides an absolute voltage to compare to the input voltage to
determine the proper digital code
5
.
a. Error budgets for an analog-to-digital converter (ADC) and a voltage reference; or digital-to-
analog converter (DAC) and a voltage reference combination
6
.
b. Other data converter error sources, effective resolution, and number of bits
7, 8
.
c. Tools and calculators for converter accuracy and clock jitter, signal bandwidth, and THD
9, 10
.
3. In a voltage detector circuit, the reference is used as an absolute threshold to set the trip point
11
.
The required specifications depend on the application. This article discusses the different types of voltage
references, their key specifications, and design tradeoffs. It offers information to help designers select the
optimum voltage reference for their applications.
The Ideal
An ideal voltage reference has a perfect initial accuracy and maintains its voltage independent of changes
in load current, temperature, and time. In the real world, a designer must make tradeoffs such as: initial
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