stm32f3 using comparator with opamp.

[jiwoobong]

Posted on July 03, 2013 at 06:21

Hello, 

I'm on stm32f3.

As far as I know, comparators on the device is very fast so it's very suitable to detect short circuit and over current condition in 50 ns. but most of shunt resistor has very LOW value. so it should be amplified to be used for comparator's input. 

on stm32f3 it has PGA. could I pre amplify by using PGA? but  dose a comparator with relatively slow opamp makes sense? .. 

or is there something that PROs do? 

Thank  you for reading. and answering in advance. 

#stm32f3 #comparator #opamp #pga

[frankmeyer9]

Posted on July 03, 2013 at 08:54

That depends on your design requirements.

How much voltage drop and power dissipation across the shunt can you accept ?

How long can your application hardware tolerate a short circuit ?

These are questions you need to answer, and probably investigate before.

And taking usual opamp offset, noise and temperature drift figures into account, you can design the appropriate working range for your circuitry. This may require an amplification of the shunt voltage, or not.

or is there something that PROs do?

 

Often, the PROs are required to do it as cheap as possibly, sacrificing performance and quality for BOM costs. That depends on your objective.