DC1205A Analog Devices

DEMO MANUAL DC1205A LT3592: Step-Down 500mA LED Driver with 10:1 Dimming DESCRIPTION Demonstration circuit 1205A features the LT3592 36V the LT3592. The minimum input voltage to run the step- step-down 500mA LED driver with 10:1 dimming. The down converter at 2.2MHz with a given string of LEDs is demonstration circuit is designed to drive two red 500mA shown in Figure 2. LEDs mounted on the PCB from a wide input voltage range. The LT3592 data sheet gives a complete description of The high 2.2MHz switching frequency permits the use of the part, operation and applications information. The a small inductor and ceramic capacitors to save space data sheet must be read in conjunction with this Demo and cost. Current mode control provides fast transient Manual for DC1205A. The LT3592 is assembled in a 10-lead response and cycle-by-cycle current limit for short-circuit plastic DFN (3mm 2mm) DDB package with a thermally protection. The LEDs have two brightness settings. With enhanced ground pad. Proper board layout is essential BRIGHT pulled high or left oating, the two red LEDs are for maximum thermal performance. See the data sheet driven with 500mA. With BRIGHT pulled to GND, the LED section Layout Hints. current drops to 50mA for 10:1 analog dimming. Design les for this circuit board are available at The typical ef ciency of the LT3592 DC1205A is 85% DEMO MANUAL DC1205A QUICK START PROCEDURE Demonstration circuit 1205A is easy to set up for evalu- 3. Tie BRIGHT terminal to GND terminal and observe ating the LT3592 36V step-down 500mA LED driver with the LED current dropping to 50mA as brightness also 10:1 dimming. Follow the test procedure outlined below decreases. and see Figure 3. 4. Use the SHDN terminal to turn the LEDs on and off by 1. Set up DC1205A as shown in Figure 3 with hand-held respectively oating or grounding the terminal. multimeters, and a bench supply (power turned off) with voltage greater than the LED string (approximately 3.5V to 5V) and less than 36V. 2. Turn on the bench power supply and observe a con- stant 500mA through the string of LEDs with BRIGHT terminal oating. OPTIONAL + A + OPTIONAL DC1205 F03 Figure 3. Proper Measurement Equipment Setup dc1205af 2 V + V +