DEMO CIRCUIT 1028 LT3513 QUICK START GUIDE LT3513EUHF 2MHz, High Current 5 Output Switching Regula- tor for TFT-LCD Panels DESCRIPTION Demonstration circuit 1028 a highly integrated, 5 out- tive batteries, distributed supplies and wall transform- put regulator for TFT LCD panels featuring LT 3513, ers. which comes in the 38-pin QFN package. The All four switchers are synchronized to the internal DC1028A has an input voltage range from 8 to 30V, 2MHz clock, allowing the use of low profile inductors and produce a 5V logic voltage. A lower voltage logic and ceramic capacitors. They all have soft start to supply can be generated from this 5V by adding an limit inrush current. external NPN driven by a linear regulator. The other The LT3513 datasheet gives a complete description of three regulators provide the three voltages required by the part, operation and application information. The data- LCDs: a higher power boost regulator to generate sheet must be read in conjunction with this quick start AVDD, a lower power boost to gerneated VON and an guide for demo circuit 1028A. inverting converter to provide VOFF. An internal high Design files for this circuit board are available. Call side PNP provides delayed turn on of the VON signal. the LTC factory. The LT3513s wide input voltage range allows it to , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT and accept a variety of power sources, including automo- PowerPath are trademarks of Linear Technology Corporation. o Performance Summary ( T = 25 C ) A PARAMETER FOR BUCK REGULATOR CONDITION VALUE Minimum Input Voltage 8V Maximum Input Voltage 30V Output Voltage V V =8V to 30V, I =0 to 500mA 5V +/- 4% LOGIC IN OUT Maximum Output Current at V V =8V to 30V 500mA LOGIC IN Typical Switching frequency 2MHz QUICK START PROCEDURE Demonstration circuit 1028 is easy to set up to evaluate 3. Check for the proper output voltage. If there is the performance of the LT3513. Refer to Figure 1 for no output, temporarily disconnect the load to proper measurement equipment setup and follow the make sure that the load is not set too high. procedure below: 4. Once the proper output voltages are established, 1. With Power off, connect the input power sup- adjust the load within the operating range and observe the output voltage regulation, ripple ply to Vin and GND. Insert jumper JP1 into the voltage, efficiency and other parameters. ON position. 2. Set the input between 8V to 30V. Turn on the power at the input. 1 + + + + + + Load Load LT3513 Load A A V V + A V V + + A V A V A Load Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2 + + + Load + + + + + +