Taking a representative example of the Allegro LED Drivers (p/n A6278 / A6279) shows this data in the data sheet.

Output Current (any single output) IO
   --- test condition -------        min    typ   max   unit
   VCE = 0.7 V, REXT = 225 Ω        64.2   75.5  86.8    mA
   VCE = 0.7 V, REXT = 470 Ω        34.1   40.0  45.9    mA
   VCE = 0.6 V, REXT = 3900 Ω       4.25   5.0   5.75    mA
Output Current Matching (difference between any two outputs at the same VCE ) ΔIO
   --- test condition -------              min    typ   max   unit
   VCE(A) = VCE(B) = 0.7 V, REXT = 225 Ω    –    +1.0  +6.0    %
   VCE(A) = VCE(B) = 0.7 V, REXT = 470 Ω    –    +1.0  +6.0    %
   VCE(A) = VCE(B) = 0.6 V, REXT = 3900 Ω   –    +1.0  +6.0    %

For these parts matching between outputs set via a common current set resistor can vary between 1% typical to 6% worst case.

Variation due to the current set resistor and at the data point VCE of a certain value leads to a percentage of +/-15%. There is additional variation of current as the VCE voltage changes which is characterized in graph form in the part data sheet. Lastly the tolerance and tempco of the R_SET resistor will add some to the variation as well.

Michael Karas