An OLED driver is a self-contained power supply that converts line voltage into the DC voltage and current that match the electrical characteristics of OLED light panels. OLEDs have unique electrical properties that demand a dedicated driving solution. OLEDs can only be operated at DC current and in a forward direction. Driving OLEDs in constant voltage mode may adversely affect the performance and lifetime of OLED light panels since the current to the load may vary. At the nominal operating point OLEDs have a very steep voltage-luminance characteristic whereas their current-luminance characteristic is flat. This means, that the luminous flux of OLEDs is proportional to the operation current. Correspondingly, OLED light panels have to be operated with constant current drivers, otherwise variations in luminous intensity will occur. OLEDs have high parasitic capacitance and equivalent series resistance (ESR) which make them incompatible with typical constant current LED driver circuitry. An OLED can be activated only when a driver charges the OLED capacitance well above the threshold voltage of the OLED diode. Moreover, the proper function of OLEDs requires the ripple current to be controlled within ±15% of the mean DC current. Typical low cost LED drivers do not provide a clean DC signal at the output because they are usually not designed with a filtering capacitor having a large capacitance value for smoothing out or decreasing the large output current ripple. Dedicated OLED drivers are recommended because they're designed to offer current control, low output current ripple, transient overshoot protection, voltage regulation, and short circuit protection (SCP). Like LEDs, the light output of OLEDs can be adjusted by dimming drivers with PWM, DMX, DALI, and 0-10V protocols. However, OLED lighting with PWM drivers may suffer performance issues such as photometric flicker because high parasitic capacitance may cause high current- or voltage spikes at the edges of the PWM signal. A constant current reduction (CCR) driver logarithmic dimming characteristic is highly recommended for OLED dimming.
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