Building a Voltmeter, need IC datasheet help

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SUMMARY

The discussion centers on building an autoranging digital voltmeter using the ICL7107 chip. The user, Kevin Hurley, seeks clarification on the Reference High (RefHI) and Reference Low (RefLO) inputs, specifically whether Vref should be set 1V above the low input or relative to ground. Additionally, he questions the use of a potentiometer in the schematic instead of fixed resistors and inquires about the function of the COM pin. The datasheet referenced is from Intersil, specifically document fn3082.pdf.

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  • Understanding of ICL7107 chip functionality
  • Familiarity with voltage reference concepts
  • Knowledge of potentiometer applications in circuits
  • Basic principles of autoranging voltmeters
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  • Review the ICL7107 datasheet for detailed specifications and application notes
  • Learn about voltage reference configurations in analog circuits
  • Investigate the role of potentiometers versus resistors in voltage dividers
  • Explore common practices for connecting COM pins in voltage measurement circuits
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Electronics hobbyists, circuit designers, and engineers working on voltage measurement projects, particularly those utilizing the ICL7107 chip.

kjnhu
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I am building an autoranging digital voltmeter as the subject line suggests and am having a problem with the ICL7107 chip that I am using. Looking at figure 15 on: http://www.intersil.com/data/fn/fn3082.pdf
specifically RefHI and RefLO, with a 2V max input difference between the pos and neg inputs. I do not necessarily have the negative input at 0 volts, and therefore would like assistance on how to use the Vref inputs. Do I need to set Vref=1V greater than the low input, or should it be 1V with repect to ground? Also why does the figure show a potentiometer rather than simply using resistors? Also should I just short the COM pin to my low input? I am unsure of how it actually functions after reading the cryptic explanation on the data sheet. Thank you for your assistance.
Kevin Hurley
 
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