This board is a simple carrier for Allegro’s ±30A ACS714 Hall effect-based linear current sensor. This version accepts a bidirectional current input with a magnitude up to 30 A. The output is an analog voltage (66 mV/A) centered at 2.5 V with a typical error of less than 1.5%
More info:http://www.pololu.com/catalog/product/1187