Buck Converter Supports LED Color Mixing

Oct 17, 2006 11:26 PM

International Rectifier has introduced 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.

Rated at 200 V or 600 V, the IRS254x series incorporates a continuous mode, time-delayed hysteretic buck regulator to control the average load current within a tolerance of 5%, using an accurate on-chip band gap voltage reference. An external high-side bootstrap circuit drives the buck switching element at high frequencies up to 500 kHz. A low-side driver is also provided for synchronous rectifier designs.

The ICs deliver a micro-power startup of less than 500 µA for extremely low losses at turn-on and a deadtime of 140 ns 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.

These ICs use a high-voltage IC process that incorporates high-voltage level-shifting and termination technology to deliver superior electrical over-stress protection and higher field reliability. Parameters are shown in the table.

Part Number	Package	Voltage (Volts)	load current regulation	Micro-power Startup (µA)	Deadtime (ns)	Frequency (kHz)
IRS2540xPbF	DIP8, S08	200	+/- 5%	<500	140	<500
IRS2541xPbF	DIP8, S08	600	+/-5%	<500	140	<500

All in 10,000-unit quantities, pricing begins at $0.81 each for the IRS2540PbF and IRS2540SPbF and $0.83 for the IRS2540STRPbF. Pricing for the IRS2541PbF and IRS2541SPbF begins at $0.89 and $0.91 for the IRS2541STRPbF.