BD9109FVMEVK-101 ROHM

ROHM Switching Regulator Solutions Evaluation Board: Synchronous Buck Converter Integrated FET No.000000000 BD9109FVMEVK-101 (3.3V 0.8A Output) Introduction This application note will provide the steps necessary to operate and evaluate ROHMs synchronous buck DC/DC converter using the BD9109FVM evaluation boards. Component selection, board layout recommendations, operation procedures and application data is provided. Description This evaluation board has been developed for ROHMs synchronous buck DC/DC converter customers evaluating BD9109FVM. While accepting a power supply of 4.5-5.5V, an output of 3.3V can be produced. The IC has internal 350mohm Pch MOSFET and 250mohm Nch MOSFET and a fixed synchronization frequency of 1 MHz. A Soft Start circuit prevents in-rush current during startup along with UVLO (low voltage error prevention circuit) and TSD (thermal shutdown detection) protection circuits. An EN pin allows for simple ON/OFF control of the IC to reduce standby current consumption. Employs a current mode control system to provide faster transient response to sudden change in load. Applications Power supply for LSI including DSP, Microcomputer and ASIC Evaluation Board Operating Limits and Absolute Maximum Ratings Limit Parameter Symbol Unit Conditions MIN TYP MAX Supply Voltage BD9109FVM V 4.5 5 5.5 V CC Output Voltage / Current V 3.234 3.300 3.366 V OUT BD9109FVM I - - 0.8 A OUT Evaluation Board Below is evaluation board with the BD9109FVM. EN Vout GND BD9673EFJ Eval Board Fig 1: BD9109FVM Evaluation Board 1 Applic ation Note Evaluation Board Schematic Below is evaluation board schematic for BD9109FVM. Fig 2: BD9109FVM Evaluation Board Schematic Evaluation Board I/O Below is reference application circuit that shows the inputs (V , EN) and the output (V ). IN OUT Fig 3: BD9109FVM Evaluation Board I/O Evaluation Board Operation Procedures Below is the procedure to operate the evaluation board. 1. Connect power supplys GND terminal to GND test point TP4 on the evaluation board. 2. Connect power supplys V terminal to V test point TP3 on the evaluation board. This will provide V to the IC U1. Please CC IN IN note that the V should be in range of 4.5V to 5.5V. CC 3. Check if shunt jumper of J1 is at position ON (Pin2 connect to Pin3, EN pin of IC U1 is pulled high as default). 4. Now the output voltage V (+3.3V) can be measured at the test point TP1 on the evaluation board with a load attached. The OUT load can be increased up to 0.8A MAX. Page 2 of 8