Atmel had sued Infineon and Infineon Technologies North America for patent infringement in the United States District Court for the District of Delaware. Atmel's court filing alleges that Infineon's 8-bit, 16-bit and 32-bit microcontrollers infringe six Atmel patents.

The allegedly-infringing Infineon products are for use in various industrial, commercial and automotive applications. Atmel's filing--its first substantive response to a lawsuit Infineon filed on April 11, 2011--also denies Infineon's allegations and seeks a judicial declaration that each of the patents Infineon asserted against Atmel is invalid and not infringed.