SanDisk has got so hacked off at LSI's claims of patent infringement and threatening letters to SanDisk's customers that it's suing the company for trade libel.

In its suit, filed last Friday in Northern District of California's US District Court, NAND flash and digital music player supplier SanDisk says LSI Corporation claimed in September 2007 that SanDisk's digital media players infringed its patents and needed licences for the intellectual property (IP) at issue. SanDisk said they didn't.

The patents involved refer to decompression for video applications, the decoding, synchronising and binarisation of MPEG audio data, and a memory chip architecture for digital storage of recorded audio data in which each of the memory cells are individually addressable.

This happened three times, following which LSI sent letters to a quarter of SanDisk's main customers reiterating the claims, under a heading that read: "RE: Unlicensed SanDisk Products." That sounds pretty threatening.

SanDisk reckons these letters amount to trade libel. It wants a legally enforceable statement from the court that it is not infringing any LSI patents, orders to stop LSI continuing the libel, damages for the harm to its reputation, and costs.

LSI provides silicon, systems and software for the storage and networking markets. It could have gone to court to enforce its patents but chose the letter route. Now it's headed for court anyway. Neither LSI nor SanDisk has issued any statement about the action. ®