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<?xml-stylesheet type="text/xsl" href="https://community.arm.com/utility/feedstylesheets/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" xmlns:wfw="http://wellformedweb.org/CommentAPI/"><channel><title>ADC for unipolar input</title><link>https://community.arm.com/developer/tools-software/tools/f/keil-forum/16334/adc-for-unipolar-input</link><description> I&amp;#39;m about to design an ADC for unipolar inputs(positive and negative) 
using an 80C552... 
A couple of questions: 
We know that Vref=(Vref+ - Vref-) 
If Vref+ = 2.5V 
and Vref- =-2.5V 
Then 
 
Vref=(2.5 - 2.5)=0 OR 
 Vref=(2.5 - (-2.5))=5 ? 
 
What will</description><dc:language>en-US</dc:language><generator>Telligent Community 10</generator><item><title>RE: ADC for unipolar input</title><link>https://community.arm.com/thread/40341?ContentTypeID=1</link><pubDate>Wed, 04 Jun 2003 18:29:41 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:3f19bf25-52e0-441e-80e5-7ace98d25ae5</guid><dc:creator>Richard Collett</dc:creator><description>&lt;p&gt;I haven&amp;#39;t looked at the specs for your particular chip, but most onboard ADCs can only measure voltage between their supply rails, and there is a spec saying Vref- cannoit be lower than ground.&lt;br /&gt;
&lt;br /&gt;
If this is the case, then you must externally level shift your voltage, either with resistor, or an opamp circuit.&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item></channel></rss>