ltc3589_scale
rdesc->min_uV = ltc3589_scale(desc->min_uV, r[0], r[1]);
rdesc->uV_step = ltc3589_scale(desc->uV_step, r[0], r[1]);
rdesc->fixed_uV = ltc3589_scale(desc->fixed_uV, r[0], r[1]);