OPA2863: Simulation review of comparator with OPA2863

The absolute maximum ratings forbid a differential input voltage of more than ±1 V. More can damage the device. (See section 8.3.3 for an explanation.)

The OPA2863 is not suitable as a comparator. Why do you want to use this device?

Hello Prayag,

I am also concerned about the use of the OPA2863 as a comparator; could you explain your decision and necessary specifications so we can best assist you with your application?  You may find an actual TI comparator device is better suited to your application, depending on your design needs.

Best,

Alec  

Hi Alec and Clemens,

I was exploring options for using digital signals for OVP in ideal diodes. 

I have considered TLV1811 which is a comparator but was checking if the op amp family can also be used as a comparator.

Thank you for clarifying this to me. 

Hi Prayag,

it's not forbidden to use an OPAmp containing protection diodes between the inputs. Even comparator circuits with externally added protection diodes between the inputs of an OPAmp can sometimes be seen. But if the input voltage is so high that the protection diodes become forward biased, a current will flow which not only must be limited to a safe value to protect the protection diodes from too high currents and the entire die from overheating, but also means an eventually undesired current flow out of the other input. In your case a certain current would flow into the 2.5V reference.

So, if you limit the current into the OPA2863 to below 10mA andf if the 2.5V voltage reference can absorb a certain reverse current, then your circuit is safe and you must not expect a damage.

But there are more issues: When exceeding the input voltage of OPAmp in a way that the differential input voltage is no longer zero, the feedback loop goes out of regulation and you may experience a considerable degradation of speed performance. This the more when the differential input voltage clamp turns-on. A comparator is designed to easily handle heavy input overvoltages without hanging all too long in saturation, if at all. But a standard OPAmp is not designed for this situation and may no longer work properly.

Because of all this, a specialized comparator may be the better choice here. But if you have a free OPAmp in the OPA2863 and inputs currents and degradation of speed play no role, then you can proceed with the OPA2863.

Kai

Good decision

Kai