LED driver has the potential to interfere the system of electronic devices if the voltage and current change rapidly. Several previous studies presented various solutions to overcome this problem such as particular converter design, component design, electromagnetic interference (EMI) filters, and spread-spectrum techniques. Compared to other solutions, the spread-spectrum technique is the most potential way to reduce the EMI in LED applications due to its limited cost-size-weight. In this paper, the effectiveness of conducted EMI suppression performance and the evaluation of its effect on LED luminance using spread-spectrum techniques are investigated. Spread-spectrum is applied to the system by modifying the switching frequency by providing disturbances at pin IADJ. The disorder is given in the form of four signals, namely square, filtered-square, triangular, and sine disturbance signals. The highest level of the EMI suppression of about 31.89% is achieved when the LED driver is given 800 mVpp filtered-square waveform. The highest reduction power level occurs at fundamental frequency reference, when it is given 700 mVpp square disruption signal, is about 81.77% reduction. The LED luminance level will reduce by 85.2% when it is given the four waveforms disruption signals. These reductions occur as the switching frequency of the LED driver does not work on a fixed frequency, but it varies in certain bands. LED brightness level has a tendency to generate a constant value of 235 lux when it is given the disruption signals. This disturbance signal causes the dimming function on the system that does not work properly.