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RD-0608

EVALUATION BOARD - IRPLLED1

1. Introduction

Development of LED technology over the last few years has produced high power devices with luminous efficacies

surpassing Fluorescent and HID light sources. These solid state light sources also posses the added advantages of

longer operating life span, up to 50000 hours as well greater robustness that other less efficient light sources.

For these reasons high power LEDs have now become a viable alternative for many general lighting applications.

High power LEDs are driven with constant regulated DC current, requiring a "ballast" or "converter" to provide the

required current from an AC or DC power source. The IRS2540/1/01/11 series Buck LED driver provides an

accurately controlled current and protects the LEDs against damage from overload, while providing the ability to

dim the light level. The IRS2540/1/01/11 will be replaced by the fully compatible revised IRS25401/11.

The IRPLLED1evaluation board is a high voltage LED driver designed to operate from a DC input voltage of 50V

to 170V and produce an output voltage of 16V-24V to supply a programmable load current of 350mA, 700mA, 1A,

or 1.5A. It uses the IRS2540/1/01/11 or revised version IRS25401/11, a high voltage, high frequency Buck control

IC for constant LED current regulation. The IRS2540/1/01/11 controls the average load current by a continuous

mode time-delayed hysteretic method using an accurate on chip band gap voltage reference. The 8-pin, 200V/600V

rated IRS2540/1/01/11 inherently provides short-circuit protection with open-circuit protection incorporated by a

simple external circuit and has dimming capability.

The evaluation board documentation will briefly describe the functionality of IRS2540/1/01/11, discuss the selection

of the output stage, switching components and surrounding circuitry. This board was tested with a single HBLED

panel for the 350mA and 700mA settings, using two similar flood boards in parallel to provide test loads for the 1A

and 1.5A settings.

Important Safety Information

The IRPLLED1 does not provide galvanic isolation of the LED drive output from the line input. Therefore if the

system is supplied directly from a non-isolated input, an electrical shock hazard exists at the LED outputs and these

should not be touched during operation. Although the output voltage is low this electrical shock hazard still exists.

It is recommended that for laboratory evaluation that the IRPLLED1 board be used with an isolated DC input

supply. The IRS2540/1/01/11 series Buck topology is suitable only for final applications where isolation is either not

necessary or provided elsewhere in the system.