DEMO CIRCUIT 1166 LT3590 QUICK START GUIDE LT3590 48V Buck-Mode LED Driver DESCRIPTION WARNING! Do not look directly at operating LED. This circuit produces light that can damage eyes. Demonstration circuit 1166 is a 48V Buck-Mode LED Driver featuring the LT3590. The LT3590 is a fixed frequency buck mode converter specifically designed to drive up to 10 LEDs in series from a 48V DC source. Series connection of the LEDs provides identical LED currents of up to 50mA, resulting in uniform brightness and eliminating the need for ballast resistors. A fixed frequency current mode architecture results in stable operation over a wide range of input voltage and load condition. The high switching frequency allows using tiny components for the circuit. The LT3590 datasheet gives complete descriptions of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for working on or modifying the demo circuit 1166. Design files for this circuit board are available. Call the LTC factory. L, LTC, LTM, LT are trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. PERFORMANCE SUMMARY Specifications are at TA = 25°C SYMBOL VIN DMAX IQSHDN FSW VREG Eff PARAMETER Input Supply Range Maximum Duty Cycle Quiescent Current in Shutdown Switching Frequency VREG Pin Voltage Efficiency CONDITIONS MIN 4.5 90 VIN = 48V 1mA load on VREG pin VIN = 48V; VLED = 30V; ILED = 50mA 650 3.1 TYP MAX 55 15 850 3.3 90 20 1050 3.5 UNITS V % µA KHz V % QUICK START PROCEDURE Demonstration circuit 1166 is easy to set up to evaluate the performance of the LT3590. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 1. Place jumpers in the following positions: JP1 ON 3. With power off, connect LEDs to LED+ and LED-. 4. Turn on the power at the input. NOTE. Make sure that the input voltage does not exceed 55V. 5. Check for the proper output voltage and current. 2. With power off, connect the input power supply to VIN and GND. 1 LT3590 Figure 1. Proper Measurement Equipment Setup 2 LT3590 3