BD9329AEFJ_EVK

ROHM Switching Regulator Solutions Evaluation Board: Step-down Switching Regulator With Built-in Power MOSFET No.0000000014 BD9328EFJ / BD9329AEFJ (12V | 2A / 3A Output) ●Introduction This application note will provide the steps necessary to operate and evaluate ROHM’s step-down switching regulator using the BD9328EFJ/BD9329AEFJ evaluation boards. Component selection, board layout recommendations, operation procedures and application data is provided. ●Description This evaluation board has been developed for ROHM’s step-down switching regulator customers evaluating BD9328EFJ and/or BD9329AEFJ. While accepting a wide power supply of 4.2-18V, a step down output of 3.3V or any external resistor defined voltage can be produced. The ICs have two integrated low resistance N-channel MOSFETs and a fixed synchronization frequency of 380 kHz. 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. ●Applications Distributed Power Systems Pre-regulator for linear regulators ●Evaluation Board Operating Limits and Absolute Maximum Ratings Limit Parameter Symbol Unit MIN TYP MAX Conditions Supply Voltage BD9328EFJ VCC 4.2 12 18 V BD9329AEFJ VCC 4.2 12 18 V BD9328EFJ VOUT - 3.3V - V BD9329AEFJ VOUT - 3.3V - V BD9328EFJ IOUT - - 2 A BD9329AEFJ IOUT - - 3 A Output Voltage / Current ●Evaluation Board Below is the evaluation board with the BD9328EFJ. BD9329AEFJ eval board uses the same components and board layout Vout Vin High E N Low 1 Application Note ●Evaluation Board Schematic Below is the evaluation board schematic for BD9328EFJ. BD9329AEFJ eval board uses the same schematic ●Evaluation Board I/O Below is the reference application circuit that shows the inputs (Vin and EN) and the output (SW and FB) ●Evaluation Board Operation Procedures Below is the procedure to operate the evaluation board 1. 2. 3. Connect GND to a GND pin on the evaluation board Connect Vin to the +12V_Vin pin. This will provide Vin to the Vin pin of the IC i. Note: EN pin is pulled high as when SW1 is high (white arrow) Now output power can be measured from the +3.3V_Vout pin on the evaluation board with a load attached Page 2 of 9 Application Note ●Reference Graphs Application Data for BD9328EFJ Below graphs shows load characteristics, transient responses and efficiency of the BD9328/9 eval board. Page 3 of 9 Application Note ●Reference Graphs Application Data for BD9329AEFJ Below graphs shows the load characteristics, transient responses and efficiency of the BD9329AEFJ eval board. Page 4 of 9 Application Note ●Evaluation Board Layout Guidelines Below are the guidelines that have been followed and recommended for BD9328EFJ and BD9329AEFJ designs Note: For applications operating at or near maximum voltage conditions (20V max.), additional precautions regarding heat dissipation need to be considered during board layout. The provided evaluation board is a 2-layer board meant for evaluation purposes only. At maximum conditions, the IC’s internal thermal shutdown detection circuit will be potentially initiated and the output disabled until the junction temperature falls. For final designs operating near these conditions, we recommend using one of the below PCB options for better heat dissipation of the IC. 1) Use of a 4-layer PCB with internal GND planes connected to the IC GND pins 2) Use of a 2-layer PCB with a heat sink attached to the IC package 3) Use of a 2-layer PCB with a copper plane (>1oz) attached to the IC Page 5 of 9 Application Note Page 6 of 9 Application Note Page 7 of 9 Application Note ●Evaluation Board BOM Below is a table with the build of materials. Part numbers and supplier references are provided. ※ Note: In this example, the nominal resistance values of R1 and R2 were selected to set a 3.3 V output. Page 8 of 9 Application Note Page 9 of 9