Settling Times Affect ADC Accuracy

The error band voltage equals the voltage represented by one least significant bit at the analog-to-digital converter.
The error band voltage equals the voltage represented by one least significant bit
at the analog-to-digital converter.

Return to Article

View Comments: Newest First|Oldest First|Threaded View
Jon Titus
User Rank
Re: Reference also important
Jon Titus   6/20/2012 1:30:40 PM
Thanks for information about the ADC reference.  I had always thought the current draw was constant.

User Rank
Reference also important
Walt   6/20/2012 1:14:33 PM
Yes, this subject becomes even more important when you are sampling from an analog multiplexer.  Then the multiplexer output must settle before the sample is taken, which must also settle. :-)

Another similar important note is at the ADC reference.  Like the input itself, some ADCs draw small surge currents from the reference, so a well thought out capacitance at the reference and a low impedance reference voltage source may reduce complications (and confusion) when figuring out settling time.

Nancy Golden
User Rank
Re: Great Topic!
Nancy Golden   6/19/2012 6:33:33 PM
I think that is where experience comes into play, Jon - and why it is so important for junior engineers to learn from senior engineers. I am forever grateful for the engineers that took the time to teach me real world things that you don't necessarily learn (or remember) from school - including settling times!

Jon Titus
User Rank
Re: Great Topic!
Jon Titus   6/19/2012 6:00:13 PM
Thanks, Nancy.  Often we overlook details that later cause problems.  I know of several cases in which not accounting for settline time caused erroneous measurements.  Thankfully the people involved discovered the problem.

Nancy Golden
User Rank
Great Topic!
Nancy Golden   6/19/2012 3:06:22 PM

Great article, Jon – thanks so much for sharing on a sometimes overlooked but extremely important part of taking accurate measurements. Settling times should be taken into account and I think how that is best handled depends on the circuitry, what is being measured and what is being used to take the measurements. On test sets we would keep cables as short as possible and in the old days we would simple do that through software by trial and error to come up with a reliable software delay (scary I know!) However, with the systems we were working on we were mostly taking DC measurements that were extremely repeatable so it worked out okay. I really appreciate the variety of solutions you offered – with the complexity of today's designs they offer great solutions and makes me want to go experiment!

Partner Zone
More Blogs
According to a Randstad Engineering compilation of salary studies, engineering salaries are increasing beyond inflation, with employers paying to keep potential suitors away from their employees.
The company says it anticipates high-definition video for home security and other uses will be the next mature technology integrated into the IoT domain, hence the introduction of its MatrixCam devkit.
Siemens and Georgia Institute of Technology are partnering to address limitations in the current additive manufacturing design-to-production chain in an applied research project as part of the federally backed America Makes program.
Check out these gifts that will make you the hero of your Secret Santa party.
Independent science safety company Underwriters Laboratories is providing new guidance for manufacturers about how to follow the latest IEC standards for implementing safety features in programmable logic controllers.
Design News Webinar Series
11/10/2015 11:00 a.m. California / 2:00 p.m. New York
10/29/2015 11:00 a.m. California / 2:00 p.m. New York
10/20/2015 8:00 a.m. California / 11:00 a.m. New York
12/2/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jul 6 - 10, Building Raspberry Pi Controllers with Python
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service