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university:courses:electronics:electronics-lab-opamp-comparator [16 Feb 2020 21:17]
Doug Mercer [The op-amp as a "comparator":]
university:courses:electronics:electronics-lab-opamp-comparator [16 Feb 2020 21:18]
Doug Mercer [The op-amp as a "comparator":]
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 <WRAP centeralign>​Figure 1a, An op-amp used as a comparator</​WRAP>​ <WRAP centeralign>​Figure 1a, An op-amp used as a comparator</​WRAP>​
  
-Op Amps and comparators may seem interchangeable at first glance based of their symbols and pinouts. The Analog Parts Kits is supplied with a variety of op-amps and the AD8561 high speed voltage comparator that was used in other activities. Some designers might be tempted to use or substitute readily available op amps as voltage comparators in their projects. There are very important differences however. Comparators are designed to work without negative feedback or open-loop, they are generally designed to drive digital logic circuits from their outputs, and they are designed to work at high speed with minimal instability. Op amps are not generally designed for use as comparators,​ their input structures may saturate if over-driven which may cause it to respond comparatively slowly. Many have input stages which behave in unexpected ways when driven with large differential voltages or beyond the specified common mode range. In fact, in many cases, the differential input voltage range of an op amp is limited or clamped to prevent damage to the input stage devices.+Op Amps and comparators may seem interchangeable at first glance based on their symbols and pinouts. The Analog Parts Kits is supplied with a variety of op-amps and the AD8561 high speed voltage comparator that was used in other activities. Some designers might be tempted to use or substitute readily available op amps as voltage comparators in their projects. There are very important differences however. Comparators are designed to work without negative feedback or open-loop, they are generally designed to drive digital logic circuits from their outputs, and they are designed to work at high speed with minimal instability. Op amps are not generally designed for use as comparators,​ their input structures may saturate if over-driven which may cause it to respond comparatively slowly. Many have input stages which behave in unexpected ways when driven with large differential voltages or beyond the specified common mode range. In fact, in many cases, the differential input voltage range of an op amp is limited or clamped to prevent damage to the input stage devices.
  
 <note important>​Warning:​ Using op-amps with built-in input clamps as a voltage comparator may damage the IC!</​note>​ <note important>​Warning:​ Using op-amps with built-in input clamps as a voltage comparator may damage the IC!</​note>​
university/courses/electronics/electronics-lab-opamp-comparator.txt · Last modified: 03 Jan 2021 22:12 by Robin Getz