# Measuring current drawn on a 12V rail

I'm looking for a high side current monitor which can measure 0-3A on a 12V rail with either a built in sense resistor or with a hall effect current sensor. I'm also space constrained, to SOT-23 or so in size. Does anyone have any suggestions?

For a SOT-23 you have for instance the Zetex ZXCT1009. This has a transconductance of 10mA/V; a short PCB trace could serve as current sensor. A 1cm zigzag trace 0.2mm wide then gives you 250$\mu$A/A, so a 1k$\Omega$ load resistor will result in 750mV full scale.