Analog or gate

[v1.5]

Hi.
Im currently designing a three leg shunt circuit. Im reading every shunt voltages using INA180A1 and output of the current sense amplifiers connected to the mcu. Mcu has internal overcurrent and short protection but system is very critical that shouldnt leave MCU alone for this purpose.

So i was thinking an analog or gate circuit to trigger gate drive fault pins for fast acting fault state. For this purpose , i must measure each ina180 output and put them together in some kind of opamp circuit to pass the highest voltage one without changing main ina180 output voltage. And compare it with a fixed voltage level depending on desired threshold current using a open drain comparator. Do you know solution for that ? Im not prefering to use many opamps for this job and i dont have enough space for it so cost sensitive solutions will be better.

 

[v1.5]

I have simulated a basic circuit. There will be no negative transient for any of the inputs but i went for shortcut and added sinus signals for inputs. What do you think ?

 

[danadak]

What is latency you can tolerate for fault detection ?

That would be sum of sensor delay + INA slew rate + Comparator delay....

Will you be using hysteresis in detection so that noise does not "chatter"
the comparator decision ?

Your circuit potential for solution, although it does not determine sensor
analog gating for highest level sensor....? Diodes would have to be matched,
use Schottky's to get low Vforward to minimize error. In fact ideal diode is available -

https://www.linearaudio.net/sites/linearaudio.net/files/ideal%20diode-2.pdf

https://www.analog.com/media/en/news-marketing-collateral/solutions-bulletins-brochures/idp-web.pdf

Regards, Dana.

 

[Tony Stewart]

What design specs have you considered? Can you list all the assumptions without choosing parts?