On the surface mount package side there are even more options. The DO-214 package, also known as an “SMB” package, is designated in the part numbering scheme with the letter “S”. It is the most popular package for single chip SIDACtor devices. “A”, “B”, “C”, and “D” rated SIDACtor devices are offered in the DO-214. Splitting one lead of the DO-214 package creates the three leaded modified DO-214 package. This package supports the TwinChip, TwinSLIC and BATTRAX product lines. The Littelfuse name for this package is the compact DO-214, which uses the letter “C” in the part number. The smallest SIDACtor packages are the 3 by 3 QFN and the 3.3 by 3.3 QFN packages. These are single chip packages for the “A”, “B” and “C” rated SIDACtor devices. In the part number, Littelfuse uses the “Q 12” and “Q 22” designations respectively. The six pin “modified MS-013” package is very flexible in that it can contain three, four or even six SIDACtor chips. This “U” designated package is also used for the dual and quad BATTRAX devices. The 5 by 6 QFN package is the home for the SDP and SEP bridge devices. It fits the same printed circuit board footprint as the very popular SO-8 package. It uses the package designation code “Q 38”. Finally, the TO-263, or “D squared pack” is the surface mount version of the through hole TO-220. With the mounting tab trimmed, pin two trimmed and pins 1 and 3 formed, the TO-220 becomes a surface mount device. This “N” package is used only to support the 3000A SIDACtor family.