over current protection

[alireza7]

hi
i have a electric dc motor which  draw 0.3a in normal operation and i want to protect it and make it off when it draws 0.5a .
my idea is measure the current and read it by a microcontroller but i don't know how to measure current with low series resistance.
how can i do this? can you suggest me any ic?
i'm not sure but i think the ic's which measure current by hall effect would be more appropriate than using a shunt resistor ,what do you think?

[T3sl4co1l]

Here's a really old circuit I drew, for about that sort of thing:



Tim

[suicidaleggroll]

hi
i have a electric dc motor which  draw 0.3a in normal operation and i want to protect it and make it off when it draws 0.5a .
my idea is measure the current and read it by a microcontroller but i don't know how to measure current with low series resistance.
how can i do this? can you suggest me any ic?
i'm not sure but i think the ic's which measure current by hall effect would be more appropriate than using a shunt resistor ,what do you think?

Why would hall effect be more appropriate?  This seems like a perfect application of a shunt resistor and a current amp.  I have a lot of experience with the LMP8480, but there are tons of options there.  2.5V ADC range with a 60x gain amp and 1A current limit would use a ~40mR shunt resistor, which under normal use would only drop 12mV and burn off ~0.4mW.  Feed the output of the current amp to an analog comparator along with your MCU's ADC, and feed the comparator output to an interrupt-capable pin on your microcontroller.  Interrupt fires and you shut off the load, end-to-end reaction time should be single digit microseconds if you use a relatively quick comparator and sufficiently high bandwidth current sense amp.