QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647 1.2MHZ, SOT-23 DC/DC CONVERTER LT3467 DESCRIPTION Demonstration circuit 647 is a 1.2MHZ, SOT-23 DC/DC Converter featuring the LT®3467. The demo board demonstrates two separate DC/DC converters for different application needs. The Boost Circuit is designed to convert a 5V input to 12V output at 300mA maximum load. The SEPIC Circuit generates a constant 12V/300mA output with 10V~16V variable input. Both circuits are designed to demonstrate the soft start feature, advantages of the 1.2MHz switching frequency, the internal 42V/1.1A switch, wide input voltage range and small circuit size. These circuits are intended for space-conscious applications such Table 1. as digital cameras, cellular phones, palmtop computers and LCD displays. The 1.2MHz switching frequency, 1.1A integrated switch, small circuit size, and low component count makes the LT3467 suitable for use in many other applications, such as PC cards, miniature disk drives, xDSL power supplies, flash memory products and local 5V or 12V supplies. Design files for this circuit board are available. Call the LTC factory. LT is a registered trademark of Linear Technology Corporation Performance Summary (TA = 25°C) PARAMETERS FOR BOOST CONVERTER CONDITION VALUE Input Voltage Output Voltage VOUT 5V VIN = 5V, IOUT = 0A to 300mA Maximum Output Current 12V ±2% 300mA Typical Output Ripple VOUT VIN = 5, IOUT = 300mA 55mVP–P Typical efficiency VIN = 5, IOUT = 300mA 86% PARAMETERS FOR SEPIC CONVERTER CONDITION VALUE Minimum Input Voltage 10V Maximum Input Voltage 16V Output Voltage VOUT VIN = 10V to 16V, IOUT = 0A to 300mA Maximum Output Current 12V ±2% 300mA Typical Output Ripple VOUT VIN = 10V, IOUT = 300mA 50mVP–P Typical efficiency VIN = 10V to 16V, IOUT = 300mA 80% QUICK START PROCEDURE Demonstration circuit 647 is easy to set up to evaluate the performance of the LT3467. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 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. NOTE: When measuring the input or output voltage NOTE: Steps 1-4 are for Boost Converter only. ripple, care must be taken to avoid a long ground lead 1. Place jumper in the following positions: 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647 1.2MHZ, SOT-23 DC/DC CONVERTER On JP1 2. With power off, connect the input power supply to VIN and GND. 3. Turn on the power at the input. JP2 On 6. With power off, connect the input power supply to VIN and GND. 7. Turn on the power at the input. NOTE: Make sure that the input voltage does not NOTE: Make sure that the input voltage is set exceed 5V. between 10V and 16V. 4. Check for the proper output voltages. 8. Check for the proper output voltages. NOTE: If there is no output, temporarily disconnect NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. the load to make sure that the load is not set too high. NOTE: Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters directly across the VIN or VOUT and GND terminals. See Figure 2 for proper scope probe technique. 9. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. NOTE: Steps 5-9 are for Sepic converter only. 5. Place jumper in the following positions: Figure 1. Proper Measurement Equipment setup Figure 2. Measurement Input or Output Ripple 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 647 1.2MHZ, SOT-23 DC/DC CONVERTER 3