QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 793 SINGLE OUTPUT, DUAL PHASE SYNCHRONOUS BUCK CONVERTER LTC3709 DESCRIPTION Demonstration circuit 793 is a single output, dual phase An LT3010EMS8E-5 (5V / 50mA LDO) provides current synchronous buck converter featuring the LTC3709EUH. for the LTC3709EUHs internal logic and gate drive cir- The output voltage is 1.5V with a load rating of 30A and cuitry. The 5V bias can also be supplied externally. For the input voltage range is 7V to 24V. input voltages less than 5V, the board contains a foot- print for an LT1613 boost converter with a 5V output. The combination of dual phase operation and valley cur- rent mode control allows the converter to have a fast NOTE: If an external bias voltage is applied it needs to be load step recovery. A simple on-board dynamic load step between 4.2V and 7.0V. circuit is provided for load step testing. Other features highlighted by demonstration circuit 793 include no Design files for this circuit board are available. Call R operation, high efficiency at both heavy and light SENSE the LTC factory. loads and rail tracking. Typical applications include desk- top and notebook computers, FPGA systems, DSPs and PowerPath is a trademark of Linear Technology Corporation servers. Table 1. Performance Summary (T = 25C) A PARAMETER CONDITION VALUE Minimum Input Voltage 7V Maximum Input Voltage 24V Output Voltage V V = 7V to 24V, I = 0A to 30A 1.5V 2% OUT IN OUT Maximum Output Current 30A Typical Output Voltage Ripple V = 12V, I = 30A (20MHz BW) 25mV IN OUT PP Typical Switching Frequency 310kHz V = 24V, I = 30A 86.6% IN OUT Typical Efficiency V = 12V, I = 30A 89.5% IN OUT (+5V bias supplied externally) V = 7V, I = 30A 89.9% IN OUT Airflow T 50C No airflow AMB QUICK START PROCEDURE Demonstration circuit 793 is easy to set up to evaluate 2. With power off, connect the input power supply to Vin the performance of the LTC3709EUH. Refer to Figure 1 and GND. for proper measurement equipment setup and follow the 3. Turn on the power at the input and set the input volt- procedure below: age to 12V. 1. Place jumpers in the following positions: 4. Check for the proper output voltage. V should OUT MODE SELECT CCM range from 1.47V to 1.53V. TRACK INT 5. Apply 30A load and re-check the regulation. +5VSEL LDO 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 793 SINGLE OUTPUT, DUAL PHASE SYNCHRONOUS BUCK CONVERTER 6. Once the proper output voltages are established, ad- just the load and input voltage within their respective operating range and test the output voltage regula- tion, output voltage ripple, efficiency, rail tracking, load step response and other parameters or features. 2