DEMO CIRCUIT 1024 LT3494START AND LT3494A QUICK GUIDE LT3494 and LT3494A Micropower Low Noise Boost Converters With Output Disconnect DESCRIPTION Demonstration circuits 1024A-A and 1024A-B are Micropower Low Noise Boost Converters With Output Disconnect featuring the LT3494 and LT3494A respectively. The demo circuits demonstrate small size and low component count in Boost configuration. Both demo versions are designed to convert a 3V-4.2V source to 15V. The only difference is in the load capability. The 1024A–A supplies 17mA at 3Vin while the 1024A–B supplies 27mA, also at 3Vin. The LT3494 features integrated Schottky diode, output disconnect function, dimming control, output sense resistor and non-audible switching frequency over the entire load range. A 2-3% improvement in efficiency can be achieved by adding an external CMDSH-3 diode. A place holder is available on the back of the board. These circuits are intended for space-conscious applications such as OLED power, MP3 Players, and Low Noise Bias Supplies. 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 DC1024A-A SYMBOL VIN VOUT VOUT VOUT PARAMETER Input Supply Range Output Voltage Range Output Voltage Range Output Voltage Range RIPPLE EFFICIENCY Load at Vout EFFICIENCY Load at VCAP CONDITIONS VIN VIN VIN VIN VIN VIN = = = = = = 3V, ILOAD = 3.6V, ILOAD 4.2V, ILOAD 3.6V, ILOAD 3.6V, ILOAD 3.6V, ILOAD 17mA = 25mA = 32mA = 25mA = 25mA = 25mA PERFORMANCE SUMMARY DC1024A-B SYMBOL VIN VOUT VOUT VOUT PARAMETER Input Supply Range Output Voltage Range Output Voltage Range Output Voltage Range RIPPLE EFFICIENCY Load at Vout EFFICIENCY Load at VCAP Specifications are at TA = 25°C = = = = = = 3V, ILOAD = 3.6V, ILOAD 4.2V, ILOAD 3.6V, ILOAD 3.6V, ILOAD 3.6V, ILOAD TYP 15 15 15 20 77 79 MAX 4.2 15.45 15.45 15.45 UNITS V V V V mV % % Specifications are at TA = 25°C CONDITIONS VIN VIN VIN VIN VIN VIN MIN 3 14.55 14.55 14.55 27mA = 35mA = 44mA = 35mA = 35mA = 35mA MIN 3 14.55 14.55 14.55 TYP 15 15 15 20 74 77 MAX 4.2 15.45 15.45 15.45 UNITS V V V V mV % % 1 LT3494 AND LT3494A QUICK START PROCEDURE Demonstration circuit 1024 is easy to set up to evaluate the performance of the LT3494 and LT3494A. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 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 Run 2. With power off, connect the input power supply to Vin and GND. 2 3. Turn on the power at the input. 4. Check for the proper output voltages. Vout1 = 14.55V to 15.45V. 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 voltage is established, adjust the load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. LT3494 AND LT3494A Figure 1. Proper Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 3 LT3494 AND LT3494A Efficie ncy at 3.6Vin 80 Efficiency in % 78 76 LT3494 74 LT3494A 72 70 68 66 0.00 10.00 20.00 30.00 40.00 load in mA Efficiency Comparison Between LT3494 and LT3494A 4 LT3494 AND LT3494A 5