TLV9062: Using Opamps as Comparators

Hey Keith, 

The article by Tim discusses the key care abouts: https://www.allaboutcircuits.com/industry-articles/using-operational-amplifiers-as-comparators/

Here is the conclusion: 

Op-amps configured to operate as comparators provide a low-cost and small PCB footprint alternative to dedicated comparators. You must consider four main op-amp characteristics to ensure expected performance, however:

• The input differential clamping diodes.
• The input common-mode voltage.
• The slew rate.
• The overload recovery time.

The op-amp must be void of input clamping diodes; otherwise, excessive current may flow through the inputs and cause damage. Do not exceed the input common-mode voltage range, or else undesirable effects such as phase reversal may occur. Finally, account for both slew rate and overload recovery in the output signal’s transition time to avoid timing errors and inaccurate readings in the circuit. By understanding how each of these characteristics affects circuit performance, you can design a robust and accurate system.

 All the best,
Carolina

Hi Keith,

every OPAmp can be used as a comparator. It always depends on speed and actual circuitry whether a simple OPAmp can do the comparator job or not and if additional current limiting circuitry at the input(s) is needed or practical at all.

If the OPAmp is input rail-to-rail and does not contain protection diodes between the inputs to limit the differential input voltage, then the answer solely depends on speed issues.

From my experience I would take an OPAmp as comparator only in the least demanding applications. There are so many nice comparators arround today that there's hardly an excuse for taking an OPAmp as comparator.

Kai

Keith,

Even op amps with input to input diodes could be used if done so with care and consideration. Some op amps consume more power in comparator mode. Other op amps consume less power. In almost every case, an actual comparator will work better.