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OPA140: Can it uses as comparator?

[FAE] Andrew Wang
Genius 10685 points

Part Number: OPA140
Other Parts Discussed in Thread: OPA197

Hi Team,

Quick question, can OPA140 use as comparator? Does it have back to back diode inside?

Thanks!

Andrew

  • 0
    TI__Guru* 93105 points
    Hello Andrew,

    The OPA140 can be used as a comparator providing the limitations of an Op amp are considered when used in such an application. OPA140 datasheet Figure 37 - Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application, does not show any back-to-back diodes across the JFET inputs which isn't too surprising. The back-to-back input diodes are more often found on the bipolar input Op amps.

    Do note the common-mode input voltage (Vcm) is limited to a maximum positive voltage of (V+) - 3.5 V on the high end and that should not be exceeded. The low Vcm is (V-)- 0.1 V so that shouldn't be an issue.

    The newer OPA197 makes a very good comparator because of its RIRO architecture, which allows for a Vcm range extending 100 mV beyond the positive and negative supply rails. Its has faster overload recovery time than the OPA140, and a slew rate of 20 V/us equal to that of OPA140.

    Regards, Thomas
    Precision Amplifiers Applications Engineering