Figure2. LT8495 Max Load Current (Typical) vs Input Voltage DEMO MANUAL DC2205A LT8495 SEPIC/Boost Converter with 2A, 70V Switch, 9A Quiescent Current, POR and Watchdog Timer DESCRIPTION Demonstration circuit 2205A is a monolithic SEPIC con- Low Ripple Burst Mode operation increases the efficiency verter featuring LT 8495. The demo board is designed for at the light load while keeping the output ripple below 5V output from a 3V to 60V input at 450kHz switching 10mV. Figure 1 shows the demo board efficiency at 12V frequency. The max output current is 1A when the input input voltage. Figure 2 shows the max load current with voltage is above 12V, and is reduced with lower input volt- different input voltages of the demo board. age. The LT8495 is a monolithic switching regulator with The LT8495 data sheet gives a complete description of the a power-on reset and watchdog timer. Quiescent current part, operation and application information. The data sheet can be less than 9A when operating. Dual supply pins must be read in conjunction with this demo manual for (V and BIAS) allow the part to automatically operate IN demo circuit 2205A. The LT8495 is assembled in a 20-lead from the most efficient supply. plastic TSSOP package. Proper board layout is essential The switching regulation, watchdog timer and reset detec- for maximum thermal and electrical performance. See the tion functions are controlled by the SWEN, WDE and RSTIN data sheet sections for details. respectively. The reset and watchdog timeout periods are Design files for this circuit board are available at independently adjustable using external capacitors C5 and DEMO MANUAL DC2205A QUICK START PROCEDURE Demonstration circuit 2205A is easy to set up to evalu- 2. With power off, connect the input power supply to V IN ate the performance of the LT8495. Refer to Figure 3 for and GND. Make sure that the input voltage does not proper measurement equipment setup and follow the exceed 60V. procedure below. 3. With power off, connect loads from V to GND. OUT Note. When measuring the input or output voltage ripple, 4. Turn on the power at the input. care must be taken to avoid a long ground lead on the 5. Check for the proper output voltages (V = 5V). oscilloscope probe. Measure the input or output voltage OUT ripple by touching the probe tip directly across the V IN Note. If there is no output, temporarily disconnect the load or V and GND terminals. See Figure 4 for the proper OUT to make sure that the load is not set too high or is shorted. scope technique. 6. Once the proper output voltages are established, adjust 1. Place JP1 on the RST position to enable the watchdog the load within the operating ranges and observe the timer. It can be disabled by placing JP1 on the GND output voltage regulation, ripple voltage, efficiency and position. other parameters. Figure3. Proper Measurement Equipment Setup dc2205afa 2