QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1046A HIGH EFFICIENCY 48V BUCK BOOST DC/DC SUPPLY LTC3780EG/LTC4440ES6 DESCRIPTION Demonstration circuit 1046A is a non-isolated, high efficiency buck-boost DC/DC supply featuring LTC®3780EG and LTC®4440ES6. The LTC3780 is a high performance 4-switch synchronous buck boost regulator and the LTC4440 is a 100V-rated FET driver. The input voltage of the demo board is designed for 36V to 72V. The output voltage is 48V. At 25C° room temperature, the maximum output current is 5A without a cooling fan and 6A with 150LFM air flow for cooling. An optional 12V bias flyback supply using the LTC3803 is stuffed on the board to power the LTC3780 and LTC4440. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. Table 1. Performance Summary (TA = 25°C) PARAMETER CONDITION VALUE Input Voltage Min / Max 36V-72V Output Voltage VOUT IOUT = 0A to 6A 48V ± 2% VIN = 36V to 72V, no fan, at room TA=25C° 5A VIN = 36V to 72V, 150LFM air flow, at room TA=25C° 6A 36V to 72V input, typical 300kHz VIN = 36V, VOUT = 48V, IOUT = 6A 96.8% Typical VIN = 48V, VOUT = 48V, IOUT = 6A 96.6 % Typical VIN = 72V, VOUT = 48V, IOUT = 6A 96.4 % Typical Maximum Output Current Switching frequency Full Load Efficiency QUICK START PROCEDURE Demonstration circuit 1046A is easy to set up to evaluate the performance of the LTC3780EG. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1046A HIGH EFFICIENCY 48V BUCK BOOST DC/DC SUPPLY 1. 2. With power off, connect the input power supply to VIN and GND. Connect the load between VOUT, and GND. Preset the load current at 0A (minimum). Refer to Figure 1 for correct test set up. The default position of FCB jumper JP1 is CCM. Turn on the input power. NOTE: Make ceed 72V. sure that the input voltage does not ex- 3. Check for the proper output voltage in the range of 47.0V to 49.0V. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 4. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Figure 1. Proper Measurement Equipment Setup 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1046A HIGH EFFICIENCY 48V BUCK BOOST DC/DC SUPPLY Figure 2. Measuring Input or Output Ripple LTC3780_LTC4440: Efficiency vs. Load Current 100% 98% 96% 94% Efficiency (%) 92% Vin=36V 90% Vin=48V 88% Vin=72V 86% 84% 82% 80% 78% 76% 74% 0 1 2 3 4 5 6 Load Current (A) Figure 3. Typical Supply Efficiency vs Load Current at 36V, 48V and 72V input 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1046A HIGH EFFICIENCY 48V BUCK BOOST DC/DC SUPPLY 4 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1046A HIGH EFFICIENCY 48V BUCK BOOST DC/DC SUPPLY 5