QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878 1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER LTC3458LEDE DESCRIPTION Demonstration circuit 878 is a 1MHZ Synchronous Step-Up DC/DC Converter featuring the LTC®3458LEDE. The demo board demonstrates a DC/DC boost converter, with a 1.7A switch, providing 5V at 300mA to 900mA depending on input voltage. The circuit demonstrates the advantages of output disconnect and inrush current limiting. Small circuit size and low component count make the LTC3458L suitable for use in many space-conscious applications such as handheld instruments, point-of-load converters, USB VBUS Power and OLED displays. Other integrated features include externally programmable burst mode threshold, peak current limit, soft-start, antiringing control and thermal shutdown. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. Table 1. Performance Summary (TA = 25°C) PARAMETERS CONDITION VALUE Minimum Input Voltage 2.0V Maximum Input Voltage 5V Output Voltage VOUT VIN = 2V, IOUT =300mA 5V ±3% Output Voltage VOUT VIN = 2.7V, IOUT =450mA 5V ±3% Output Voltage VOUT VIN = 3.3V, IOUT =650mA 5V ±3% Output Voltage VOUT VIN = 4.2V, IOUT =900mA 5V ±3% Typical Output Ripple VOUT VIN = 3.3V, IOUT = 650mA 30mVP–P Typical efficiency VIN =4.2V , IOUT = 900mA 86% C9 used only when operating supply with long inductive input leads. QUICK START PROCEDURE Demonstration circuit 878 is easy to set up to evaluate the performance of the LTC3458LEDE. 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, JP2 Auto on. 2. With power off, connect the input power supply to Vin and GND. 3. Turn on the power at the input. NOTE: Make sure that the input voltage does not ex- ceed 6V. 4. Check for the proper output voltages. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878 1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER NOTE: If there is no output, temporarily disconnect the load to make sure that the load is not set too high. and observe the output voltage regulation, ripple voltage, efficiency and other parameters. NOTE: Once the proper output voltages are established, adjust the loads within the operating range Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 878 1MHZ SYNCHRONOUS STEP-UP DC/DC CONVERTER 3