Two MOSFETs are employed as current-bidirectional two-quadrant switches in a bidirectional battery charger/discharger based on the dc-dc buck converter. This converter interfaces a 16 V battery to a 28 V main power bus. The max battery current is 40 A. The MOSFETs have Ron of 35 microOhms. Their body diodes have forward voltage drops of 1.0V and exhibit recovered charge, Qr, of 25 microCoulombs and reverse recovery times, trr, of 200 ns. Assume all diodes have "snappy" reverse recovery characteristics and diode stored charge is dominant cause of switching loss. Neglect all losses other than semiconductor conduction losses and switching loss induced by diode stored charge. 1. Estimate switching energy loss, conduction loss and converter efficiency when battery charged at max rate (f_sw=100kHz). 2. With external diodes added, with forward drops of 1V, Qr of 5 micro-Coulombs, trr of 4 ns, repeat analysis in part 1. 3. Determine range of frequencies the addition of external diodes improves the converter efficiency.