QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-E ACTIVE RESET ISOLATED DC/DC POWER CONVERTER LT1952 DESCRIPTION Demonstration circuit 1317A-E is isolated input to high current output 1/8th Brick footprint converter DC1317A-F, 9-36Vin to 3.3V, 20A featuring the LT 1952 switching controller with Ac- DC1317A-G, 9-36Vin to 12V, 5A tive Reset circuit. The Active Reset circuit can im- prove the efficiency in wide input voltage applica- DC1317A-H, 9-36Vin to 48V, 1.5A tions. Also, the Active Reset allows the implementa- tion of self-driven synchronous secondary rectifiers in some applications. The DC1317 circuit features soft-start which pre- vents output voltage overshoot on startup or when The DC1317A-E converts isolated 36V to 72V input recovering from overload condition. to 5V output and provides over 12A of output cur- rent. The converter operates at 260kHz with the peak The DC1317 has precise over-current protection cir- efficiency greater than 94% at 8A load. The DC1317 cuit that allows for continuous operation under short can be easily modified to generate output voltages in circuit conditions. The low power dissipation under the range from 0.6V to 48V. The output currents are short circuit conditions insures high reliability even limited by total output power of up to 150W. during short circuits. The other available versions of DC1317A are: The LT1952 can be synchronized to an external clock of up to 400kHz. Please refer to LT1952 data DC1317A-A, 36-72Vin to 3.3V, 30A sheet for design details and applications information. DC1317A-B, 18-72Vin to 5V, 25A Design files for this circuit board are available. DC1317A-C, 18-72Vin to 12V, 10A Call the LTC factory. DC1317A-D, 18-72Vin to 24V, 5A LT is a trademark of Linear Technology Corporation Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage I = 0A to 12A 36V OUT Maximum Input Voltage I = 0A to 12A 72V OUT V V = 36V to 72V, I = 0A to 12A 5V 3% OUT IN OUT Typical Output Ripple V V = 36V to 72V, I = 0A to 12A 50mV OUT IN OUT PP Nominal Switching Frequency 260kHz QUICK START PROCEDURE Demonstration circuit 1317 is easy to set up to NOTE: When measuring the input or output volt- evaluate the performance of LT1952 circuit. Refer age ripple, care must be taken to avoid a long ground to Figure 1 for proper measurement equipment lead on the oscilloscope probe. Measure the input or setup and follow the procedure below: output voltage ripple by touching the probe tip di- 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-E ACTIVE RESET ISOLATED DC/DC POWER CONVERTER rectly across the Vin or Vout and GND terminals. If there is no output, temporarily disconnect the See Figure 2. for proper scope probe technique. load to make sure that the load is not set too high. 1. With power off, connect the input power supply to 4. Once the proper output voltage is established, ad- Vin and GND. Make sure that the input power just the load within the operating range and ob- supply has sufficient current rating at minimum serve the output voltage regulation, ripple voltage, input voltage for the required output load. efficiency and other parameters. 2. Turn on the power at the input. 5. The DC1317 is equipped with an output capacitor CSYS (470uF) that approximates typical system NOTE: Make sure that the input voltage does not rail capacitance. If system board already has ca- exceed 72V. pacitance of similar value CSYS can be removed. 3. Check for the proper output voltage. Vout = 5V. Figure 1. Proper Measurement Equipment Setup 2