Advice on accurate ACS712 current sensor

Hi, regarding accuracy of readings from an acs712 current sensor, which outputs 0 - 5v. Is this a good idea…

Use a lm4040 voltage reference into a spare analog pin and use that to dynamically calibrate the analog readings?

Or is there a better way? The voltage supply to the board may not be stable so wary of just using default aref.

Also, is it OK to power a LM4040 from a digital pin? They seem to draw <10mA.