We report on the modeling of an electrically pumped nonlinear source for spontaneous parametric down-conversion in an AlGaAs single-sided Bragg waveguide. Laser emission from InAs quantum dots embedded in the waveguide core is designed to excite a Bragg pump mode at 950 nm. This mode is phase matched with two cross-polarized total-internal-reflection fundamental signal and idler modes around 1900 nm. Besides numerically evaluating the source efficiency, we discuss the crucial role played by the quantum dots in the practical implementation of the phase-matching condition along with the tuning capabilities of this promising active device.