In this paper, different sliding mode controls for DC/DC converters control are considered. Classical Buck, Boost and bidirectional Buck/Boost plants are presented for control application. A unified approach is adopted based on the mathematical tools of first- and second-order sliding mode output control. Set-up and ancillary conditions, as condenser pre-charging, are discussed and justified on a rigorous mathematical basis. Numerical simulations show the effectiveness of the proposed novel control strategy in terms of disturbance rejection and fast tracking of the output reference. Direct implementation with hysteretic controllers or PWM are possible.