add Texas SO-20 PowerPAD
Used by e.g. OPA569: http://www.ti.com/lit/ds/symlink/opa569.pdf
Further details on footprint at: http://www.ti.com/lit/an/slma004b/slma004b.pdf
Edited by Joel Guittet
Used by e.g. OPA569: http://www.ti.com/lit/ds/symlink/opa569.pdf
Further details on footprint at: http://www.ti.com/lit/an/slma004b/slma004b.pdf