DC1207A Analog Devices

DEMO MANUAL DC1207A LT3504 Quad 40V/1A Step-Down Switching Regulator with 100% Duty Cycle Operation DESCRIPTION The demo circuit 1207A is a quad current mode PWM step- size. Each output can be independently disabled using its down DC/DC converter featuring the LT 3504. The demo own RUN/SS pin. circuit is designed for 5V, 3.3V, 2.5V and 1.8V outputs The LT3504 data sheet gives a complete description of from a 5.4V to 40V input. The current capability of each the device, operation and application information. The channel is up to 1A. Individual soft-start and current limit data sheet must be read in conjunction with this quick for each output as well as synchronous function simplify start guide for the demo circuit 1207A. the complex design of quad-output power converters. Design files for this circuit board are available at Each converter is synchronized to either a common ex- DEMO MANUAL DC1207A DESCRIPTION 100 95 90 85 80 75 70 65 60 5 10 15 20 25 30 35 40 V (V) IN Figure 1. System Efficiency at f = 1MHz with All Channels Sourcing 1A Current Figure 2. Thermal Image at V = 12V, f = 1MHz with All IN Channels Sourcing 1A Current QUICK START PROCEDURE The demo circuit 1207A is easy to set up to evaluate the 3. Turn on the power at the input. performance of the LT3504. Refer to Figure 3 for proper NOTE: Make sure that the input voltage does not exceed 40V. measurement equipment setup and follow the procedure 4. Check for the proper output voltages. below: NOTE. If there is no output, temporarily disconnect the NOTE: When measuring the input or output voltage ripple, load to make sure that the load is not set too high. care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage 5. Once the proper output voltages are established, adjust ripple by touching the probe tip directly across the VIN or the load within the operating range and observe the VOUT and GND terminals. See Figure 4 for proper scope output voltage regulation, ripple voltage, efficiency and probe technique. other parameters 1. Place JP1-JP5 on ON position. 2. With power off, connect the input power supply to VIN and GND. dc1207af 2 EFFICIENCY (%)