Noqsi Aerospace, ltd. is helping to design the SXI instrument for the NeXT space mission. We are publishing the designs and documentation under a Creative Commons license. Here are the current schematics (just CCD clock drivers so far, obsolete as of 4/2010), the designer's notebook, and a presentation I gave at Osaka University in June, 2007.
TESS requires extremely precise photometry. This, in turn, requires that the CCD "bias map" be very flat and stable, requiring very stable clock drivers. This tends to cost power. But with care, a low power solution is possible. See how here.