The DC-DC converters require controllers for their voltage regulation and current control. Controllers are also essential for reliable and efficient power conversion. Designing a controller for the dual input SEPIC converter topology poses significant challenges owing to its fourth-order and non-linear characteristics. Additionally, the controller performance is influenced by load variations and operating conditions. A well-designed controller must fulfill specific objectives, including a fast-dynamic response, resilience to parameter variations, assured stability, and precise tracking performance. In this work, a robust multivariable control technique is considered for the design of a controller for integrated DC-DC converters. The digital decentralized controllers are designed for two input-integrated converters to achieve stable and reliable output voltage. A robust PID controller is designed with RST control architecture for the regulation of TI-BS and TI-MBS converters using the pole placement technique. The detailed procedural steps to design a robust controller using this technique are presented. A sixth-order closed-loop characteristic equation is formulated for Voltage and current loops and controllers are designed based on this. The desired pole location for both voltage and current control loops is assumed to be the same. To verify the effectiveness of these designed controllers, 48 V, 720 W, and TII DC-DC converters are considered for analysis and simulation. The steady-state and dynamic simulations are performed for TI-BS and TI-MBS converters under different situations, these are (i) with nominal converter parameters, (ii) variation in load current, (iii) variations in source voltage. It is observed from these simulations that the current of source-2 (ig2), and the output voltage (V0) will follow the reference values against these disturbance conditions.