Use Imagemagick, or better yet, Ghostscript.
http://www.ibm.com/developerworks/library/l-graf2/#N101C2 has an example for imagemagick:
convert foo.pdf pages-%03d.tiff
http://www.asmail.be/msg0055376363.html has an example for ghostscript:
gs -q -dNOPAUSE -sDEVICE=tiffg4 -sOutputFile=a.tif foo.pdf -c quit
I would install ghostscript and read the man page for gs to see what exact options are needed and experiment.