QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-A ACTIVE RESET ISOLATED 48V INPUT TO 3.3V 30A DC/DC POWER CONVERTER LT1952 DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN Demonstration circuit 1317A-A is isolated input to DC1317A-F, 9-36Vin to 3.3V, 20A high current output 1111////8888tttthhhh BBBBrrrriiiicccckkkk ffffoooooooottttpppprrrriiiinnnntttt converter DC1317A-G, 9-36Vin to 12V, 5A featuring the LT 1952 switching controller with Ac- DC1317A-H, 9-36Vin to 48V, 1.5A tive Reset circuit. The Active Reset circuit can im- prove the efficiency in wide input voltage applica- tions. Also, the Active Reset allows the implementa- The DC1317 circuit features soft-start which prevents tion of self-driven synchronous secondary rectifiers output voltage overshoot on startup or when recover- in some applications. ing from overload condition. The DC1317A-A converts isolated 34V to 75V input to The DC1317 has precise over-current protection cir- 3.3V output and provides over 30A of output current. cuit that allows for continuous operation under short The converter operates at 300kHz with the peak effi- circuit conditions. The low power dissipation under ciency greater than 93%. The DC1317 can be easily short circuit conditions insures high reliability even modified to generate output voltages in the range during short circuits. from 0.6V to 48V. The output currents are limited by total output power of up to 150W. The LT1952 can be synchronized to an external clock of up to 400kHz. Please refer to LT1952 data sheet for The other available versions of DC1317A are: design details and applications information. DC1317A-B, 18-72Vin to 5V, 25A DDDDeeeessssiiiiggggnnnn ffffiiiilllleeeessss ffffoooorrrr tttthhhhiiiissss cccciiiirrrrccccuuuuiiiitttt bbbbooooaaaarrrrdddd aaaarrrreeee aaaavvvvaaaaiiiillllaaaabbbblllleeee.... DC1317A-C, 18-72Vin to 12V, 10A CCCCaaaallllllll tttthhhheeee LLLLTTTTCCCC ffffaaaaccccttttoooorrrryyyy.... DC1317A-D, 18-72Vin to 24V, 5A LT is a trademark of Linear Technology Corporation DC1317A-E, 36-72Vin to 5V, 12A TTTTaaaabbbblllleeee 1111.... PPPPeeeerrrrffffoooorrrrmmmmaaaannnncccceeee SSSSuuuummmmmmmmaaaarrrryyyy PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR CCCCOOOONNNNDDDDIIIITTTTIIIIOOOONNNN VVVVAAAALLLLUUUUEEEE Minimum Input Voltage I = 0A to 30A 34V OUT Maximum Input Voltage I = 0A to 30A 75V OUT V V = 34V to 75V, I = 0A to 30A 3.3V 3% OUT IN OUT Typical Output Ripple V V = 34V to 75V, I = 0A to 30A 50mV OUT IN OUT PP Nominal Switching Frequency 300kHz QQQQUUUUIIIICCCCKKKK SSSSTTTTAAAARRRRTTTT PPPPRRRROOOOCCCCEEEEDDDDUUUURRRREEEE Demonstration circuit 1317 is easy to set up to evalu- uuuurrrreeee 1111 ffffoooorrrr pppprrrrooooppppeeeerrrr mmmmeeeeaaaassssuuuurrrreeeemmmmeeeennnntttt eeeeqqqquuuuiiiippppmmmmeeeennnntttt sssseeeettttuuuupppp ate the performance of LT1952 circuit. RRRReeeeffffeeeerrrr ttttoooo FFFFiiiigggg---- and follow the procedure below: 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-A ACTIVE RESET ISOLATED 48V INPUT TO 3.3V 30A DC/DC POWER CONVERTER NNNNOOOOTTTTEEEE:::: When measuring the input or output voltage If there is no output, temporarily disconnect the ripple, care must be taken to avoid a long ground lead load to make sure that the load is not set too high. on the oscilloscope probe. Measure the input or out- 4444.... Once the proper output voltage is established, ad- put voltage ripple by touching the probe tip directly just the load within the operating range and ob- across the Vin or Vout and GND terminals. See Figure serve the output voltage regulation, ripple voltage, 2. for proper scope probe technique. efficiency and other parameters. 1111.... With power off, connect the input power supply to 5555.... The DC1317 is equipped with an output capacitor Vin and GND. Make sure that the input power sup- CSYS (470uF) that approximates typical system ply has sufficient current rating at minimum input rail capacitance. If system board already has ca- voltage for the required output load. pacitance of similar value CSYS can be removed. 2222.... Turn on the power at the input. NNNNOOOOTTTTEEEE:::: Make sure that the input voltage does not exceed 75V. 3333.... Check for the proper output voltage. Vout = 3.3V. FFFFiiiigggguuuurrrreeee 1111.... PPPPrrrrooooppppeeeerrrr MMMMeeeeaaaassssuuuurrrreeeemmmmeeeennnntttt EEEEqqqquuuuiiiippppmmmmeeeennnntttt SSSSeeeettttuuuupppp 2