DC1757B Analog Devices

DEMO MANUAL DC1757B LTC3789EGN High Efficiency 12V/12A Buck-Boost Converter Description Demonstration circuit 1757B is a high efficiency syn- The light load operation mode of the converter is deter- chronous buck-boost DC/DC converter with a 6V to 36V mined with the MODE/PLLIN pin. Use JP2 jumper to select input voltage range. It can supply a 12A maximum load pulse-skipping mode or forced continuous mode (CCM) current with a 12V output. The demo board features the operation. The switching frequency is pre-set at about LTC 3789EGN controller. The constant frequency current 200kHz. The converter can also be externally synchronized mode architecture allows a phase-lockable frequency of up to an external clock through the MODE/PLLIN pin (PLLIN to 600kHz, while an optional output current feedback loop terminal on the board). To shut down the converter, force provides support for applications such as battery charging. the RUN pin below 1.2V (JP1: OFF). The power good With a wide input range, wide output range and seamless output (PGOOD terminal) is low when the output voltage transfers between operation modes, the LTC3789 is ideal is outside of the 10% regulation window. for automotive, telecom, distributed DC power systems Design files for this circuit board are available at and battery-powered applications. DEMO MANUAL DC1757B Quick start proce D Note: When measuring the output or input voltage ripple, Additional Notes: do not use the long ground lead on the oscilloscope probe. 1. Usually, the worst case efficiency at full load is at 6V . IN See Figure 2 for the proper scope probe technique. Short, The board can deliver more output power at higher V . IN stiff leads need to be soldered to the (+) and () terminals 2. R2 is needed for additional/constant output current of an output capacitor. The probes ground ring needs to limit only. touch the () lead and the probe tip needs to touch the (+) lead. + + + + + + LOAD Figure 1. Proper Measurement Equipment Setup + C OUT V GND OUT Figure 2. Measuring Output Voltage Ripple dc1757bf 2 ure