This work presents a binary differential phase-shift keying (DPSK) modulation technique for visible light communication (VLC) systems aimed at low to moderate data rate applications. VLC uses the modulated light of LEDs to transmit data wireless. Such feature is added into artificial lighting systems by controlling the light intensity of a source. However, in most cases, modulation capabilities for VLC are employed with the addition of extra power components, which may harm efficiency and cost standards. Therefore, single switch LED drivers are preferable to provide VLC along with average current regulation. They are standard low-cost solutions that are able to perform both functions providing a satisfactory efficiency. Hence, in this work, DPSK modulation is applied to a buck converter operating in continuous conduction mode at 250 kHz, providing a raw data rate of 125 kbps. DPSK is advantageous because it overcomes possible parameters changes at the converter, along with possible duty cycle changes given by the control system of the average current for lighting. Moreover, the system performance is evaluated by means of its bit error ratio (BER) over signal-to-noise ratio (SNR), in a line-of-sight setup with variable distances between transmitter and receiver, showing a good behaviour of a BER less than 10^-3 for about 8.1 m in a 8.4 W LED load.