The HV9861ADB1 demoboard is a high-brightness LED driver employing the patented average-mode, constant current control scheme. The power conversion stage of the HV9861ADB1 consists of a diode bridge rectifier followed by a buck converter operating with fixed off-time of 20μs. The HV9861ADB1 LED driver features tight regulation of the LED current within a few milliamps over the entire range of the input AC line and the output LED string voltage. The LED current accuracy is almost insensitive to the passive component tolerances, such as the output filter inductance or the timing resistor. The accuracy of the LED current is mainly determined by the internal 270mV ± 3% reference voltage of the HV9861A control IC and by the external current sense resistor tolerance.