Does anyone run their current sensors at the max allowed current without adding heat sinking?
I have the 20A version which quotes 1.2 mOhm as the loop resistance. At 20A that is half a watt of heat coming out of a tiny 8 pin SOIC package. All the current is carried by the four pins on one side.
My lab supply only goes up to 4A so I don't have a way of testing the real-world behaviour until I connect it to the actual thing I want to measure.
The module is the typical thing you see on ebay or Aliexpress.
The question I would have first is: Is they PCB layout per the datasheet? There are some very detailed layout notes in the datasheet. The manufacturer will be using the PCB copper as heat sink/dissipation material.
The comment I would make is, how does the size (especially the surface area) of the SOIC-8 package compare to a 1/2W resistor?
From looking at pics on web I don't think anyone is following the Allegro guidelines.
The Sparkfun and Pololu boards do at least have large through holes for screw terminals which basically forces you to use large diameter cable as the heatsink. All the others seem to be random PCB sizes.
On mine I have removed the screw terminals and soldered some copper braid tails. I think I'll also run with a shunt to reduce the through current until I'm confident that it's working OK.
mikb55:
Does anyone run their current sensors at the max allowed current without adding heat sinking?
I have the 20A version which quotes 1.2 mOhm as the loop resistance. At 20A that is half a watt of heat coming out of a tiny 8 pin SOIC package. All the current is carried by the four pins on one side.
My lab supply only goes up to 4A so I don't have a way of testing the real-world behaviour until I connect it to the actual thing I want to measure.
The module is the typical thing you see on ebay or Aliexpress.
What you may not realize is that the terminal block and the wires you screw into it are acting as heatsinks.
Its probably fine for 20A.
