DEMO CIRCUIT 1280 LT3471EDD QUICK START GUIDE LT3471EDD Dual 1.3A, 1.2MHz Boost/Inverter in 3mmx3mm DFN DESCRIPTION Demonstration circuit 1280A is a dual output converter featuring the LT3471EDD in Boost and Inverter configurations. Both converters are powered from the same 4.5V to 10V input source. The Boost converter puts out 12V at 300mA and the Inverter -12V at 200mA. The demo circuit demonstrates small size and low component count. The LT3471 operates with inputs as high as 16V but in this demo board the input is limited by the magnitude of the Boost output. In a Boost converter the input needs to be less than the output. The DC1280A is designed so that the Inverting converter can easily be configured as a Boost. Instructions are included in the schematic. Both circuits are designed to demonstrate the soft start feature, advantages of the 1.2MHz switching frequency and the internal 42V/1.3A switches. Both outputs on this demo board can be modified for higher voltages. These circuits are intended for space-conscious applications such as digital cameras, cellular phones, palmtop computers PC cards, miniature disk drives, xDSL power supplies, flash memory products, local 5V or 12V supplies and LCD displays. Design files for this circuit board are available. Call the LTC factory. L, LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered trademarks of Linear Technology Corporation. Adaptive Power, C-Load, DirectSense, Easy Drive, FilterCAD, Hot Swap, LinearView, µModule, Micropower SwitcherCAD, Multimode Dimming, No Latency , No Latency Delta-Sigma, No RSENSE, Operational Filter, PanelProtect, PowerPath, PowerSOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT, UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. PERFORMANCE SUMMARY FOR BOOST CONVERTER SYMBOL VIN VOUT PARAMETER Input Supply Range Output Voltage Range RIPPLE EFFICIENCY CONDITIONS VIN = 4.5V, ILOAD = 300mA VIN = 4.5V, ILOAD = 300mA VIN = 4.5V, ILOAD = 300mA Specifications are at TA = 25°C MIN 4.5 11.64 PERFORMANCE SUMMARY FOR INVERTING REGULATOR TYP 12 40 84 MAX 10 12.36 UNITS V V mV % Specifications are at TA = 25°C SYMBOL VIN VOUT RIPPLE EFFICIENCY PARAMETER Input Supply Range Output Voltage Range CONDITIONS VIN = 4.5V, ILOAD = 200mA VIN = 4.5V, ILOAD = 200mA VIN = 4.5V, ILOAD = 200mA MIN 4.5 -11.64 TYP -12 10 74 MAX 12 -12.36 UNITS V V mV % QUICK START PROCEDURE Demonstration circuit 1280 is easy to set up to evaluate the performance of the LT3471EDD. Re- fer to Figure 1 for proper measurement equipment setup and follow the procedure below: 1 LT3471EDD NOTE. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. 1. Place jumpers in the following positions: JP1 ON JP2 ON 4. Check for the proper output voltages. NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 5. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltages, efficiency and other parameters. 2. With power off, connect the input power supply (4.5V to 10V) to Vin and GND. 3. Turn on the power at the input. Figure 1. Proper Measurement Equipment Setup for DC1280A 2 LT3471EDD GND VIN Figure 2. Measuring Input or output Ripple Boost Conv e rte r Efficie ncy 90% 85% Efficiency (%) 80% 75% Vin = 4.5V 70% 65% 60% 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Load Cur re nt (m A) Figure 3. Boost Converter Efficiency at 4.5Vin 3 LT3471EDD Inverting Regulator Efficiency 80% 75% Efficiency (%) 70% 65% Vin = 4.5V 60% 55% 50% 0 20 40 60 80 100 120 Load Curr e nt (m A) 140 160 Figure 4. Inverting Regulator Efficiency at 4.5Vin 4 180 200 LT3471EDD 5