In this paper, we propose a novel visible light communication (VLC) based indoor positioning system (IPS) for Internet-of-Things (IoT) applications. In such systems, to minimize the harmful flickering effects due to intensity modulation of LED lamps, our proposed design only requires a single LED ceiling lamp and multiple photodiodes (PDs) at the receiver. We propose an ON/OFF switching frequency pattern of our single LED ceiling lamp that allows the use of time difference of arrival (TDOA) based positioning algorithm. The localization accuracy achieved by our proposed design is very high and the error in the estimated position of a receiver is only few millimeters (mm). This performance is comparable to the IPS systems that rely on multiple LED lamps. We also consider different arrangements of photodiodes at the receiver. Simulation results reveal that in terms of localization accuracy, circular arrangement of PDs outperforms all other considered configurations.