A high-voltage, high-frequency buck regulator control IC for AC-DC offline, non-isolated applications requiring multiple light-emitting diode (LED) circuits or requiring DC-DC color-mixing capabilities has been introduced by International Rectifier. Applications include indoor and outdoor signage as well as architectural, entertainment, design and decorative lighting. Rated at 200V or 600V, the IRS254x series incorporates a continuous mode, time-delayed hysteretic buck regulator to control the average load current within a tolerance of five percent, using an accurate on-chip band gap voltage reference.

An external high-side bootstrap circuit drives the buck switching element at frequencies up to 500kHz. A low-side driver is also provided for synchronous rectifier designs. The new ICs deliver a micro-power startup of less than 500µA and a deadtime of 140ns for continuous current regulation. Other features include auto restart, non-latched shutdown and PWM dimmable capability, incorporated into a compact 8-pin DIP or 8-pin SOIC package, also available in tape and reel.