IRPLLED1 is a high voltage DC to DC buck converter for HB LEDs constant current control evaluation board which features the IRS2540, IRS2541, IRS25401, IRS25411 LED buck regulator control IC. It incorporate a continuous mode time delayed hysteretic buck regulator to directly control the average load current using an accurate on chip bandgap voltage reference. An external high side bootstrap circuit drives the buck switching element at high frequencies. During normal operating conditions the output current is regulated via the IFB pin voltage. This feedback signal is compared to an internal high precision band gap voltage reference. An on board dV/dt filter has also been used to prevent erroneous transitioning.