Passive mode-locked laser operation based on an Yb-doped lanthanum scandium borate crystal is demonstrated. Pulse durations as short as 58 fs and 67 fs were achieved applying a Ti:sapphire- and a diode-laser pump source, respectively. The average output powers were 73 mW and 39 mW at a repetition rate of 90 MHz. The laser was broadly tunable from 1028 to 1057 nm in the sub-200 fs pulse regime.