This paper presents a new integral sliding mode control (SMC) algorithm that can handle matched uncertainties in the presence of the given fast sensor dynamics. More precisely, by selecting the sliding surface that is sufficiently faster than the sensor dynamics, it is possible to maintain unaffected the time-scale separation between sensors and plant. A modified singular perturbation technique is used to show some semi-global practical asymptotic stability of the closed loop system. By incorporating the knowledge of sensors into the SMC design and by tuning the parameters of the proposed integral SMC appropriately, the main result shows that the closed loop system can converge to a small neighborhood of the origin (the ultimate bound) from some given domain of attraction. Both the ultimate bound and the domain of the attraction are dependent of the time-scale parameter that is related to the sensor dynamics. Simulation results are presented to show the effectiveness of the proposed approach.