BD9673EFJ_EVK

ROHM Switching Regulator Solutions Evaluation Board: Step-down Switching Regulator With Built-in Power MOSFET No.0000000013 BD9673EFJ / BD9876EFJ (5V | 1.5A / 2.75A Output) ●Introduction This application note will provide the steps necessary to operate and evaluate ROHM’s step-down switching regulator using the BD9673EFJ/BD9876EFJ 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 BD9673EFJ and/or BD9876EFJ. While accepting a wide power supply of 7-42V, a step down output of 1.2V/1.8V/3.3V/5V or any other user defined voltage can be produced. The ICs have an internal 200mohm Nch MOSFET (3.5A max) and a synchronization frequency range of 200 kHz to 500 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 For general devices that have 12V/24V lines ●Evaluation Board Operating Limits and Absolute Maximum Ratings Limit Parameter Symbol MIN TYP MAX Unit Conditions Supply Voltage BD9673EFJ VCC 7 - 24 V 24V for Eval board operation BD9876EFJ VCC 7 - 24 V 24V for Eval board operation BD9673EFJ VOUT 1* - VCCx0.7 V BD9876EFJ VOUT 1* - VCCx0.7 V BD9673EFJ IOUT - - 1.5 A BD9876EFJ IOUT - - 2.75 A Output Voltage / Current *Restricted by minimum on pulse typ. 200ns *Restricted by minimum on pulse typ. 200ns ●Evaluation Board Below is the evaluation board with the BD9673EFJ. BD9876EFJ eval board uses the same components and board layout BD9876EFJ Eval Board 1 Application Note ●Evaluation Board Schematic Below is the evaluation board schematic for BD9673EFJ. BD9876EFJ eval board uses the same schematic ●Evaluation Board I/O Below is the reference application circuit that shows the inputs (Vcc, EN and Sync) and the output (Vout) ●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 Vcc to the +24V_Vin pin. This will provide Vcc to the Vcc pin of the IC i. Note: EN pin is pulled high as default Now output power can be measured from the +5V_Vout pin on the evaluation board with a load attached. The load can be increased up to 2.75A MAX. Page 2 of 10 Application Note ●Reference Graphs Application Data for BD9673EFJ Below graphs show efficiency, frequency response and load characteristics of the BD9673EFJ eval board. Page 3 of 10 Application Note ●Reference Graphs Application Data for BD9876EFJ Below graphs show efficiency, frequency response and load characteristics of the BD9876EFJ eval board. Page 4 of 10 Application Note ●Evaluation Board Layout Guidelines Below are the guidelines that have been followed and recommended for BD9673 and BD9876 designs Figure 1 Note: For applications operating at or near maximum voltage conditions (45V 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) 2) 3) Use of a 4-layer PCB with internal GND planes connected to the IC GND pins Use of a 2-layer PCB with a heat sink attached to the IC package Use of a 2-layer PCB with a copper plane (>1oz) attached to the IC Page 5 of 10 Application Note Page 6 of 10 Application Note Page 7 of 10 Application Note Page 8 of 10 Application Note ●Evaluation Board BOM Below is a table with the build of materials. Part numbers and supplier references are provided. Item Qty Ref Description Manufacturer Part Number 1 1 C1 CAP, CER, 1210, 16 V, 20%, 47 µF Murata GRM32ER61C476ME15L 2 1 C2 CAP, CER, 0603, NP0, 25 V, 5%, 6800 pF TDK Corporation C1608C0G1E682J 3 1 C3 CAP, CER, 0603, X7R, 25 V, 20%, 10000 pF TDK Corporation C1608X7R1E103M 4 1 C4 CAP, ALUM, SMD, 20%, 35 V, 33 µF Panasonic Corp EEE-FT1V330AR 5 1 C5 CAP, CER, 0603, X7R, 50 V, 10%, 0.1 µF AVX Corporation 06035C104KAT2A 6 1 D1 SBD, PMDS / SOD-106, 40 V, 3 A ROHM Semiconductor RB056L-40TE25 7 1 L1 INDUCTOR SMD 15UH 3.60A 100KHZ Signal Transformers SCRH105RY-150 8 1 R1 RES, SMD, 0805, 1/8 W, 5%, 120 kΩ ROHM Semiconductor MCR10EZPJ124 9 1 R2 RES, SMD, 0805, 1/8 W, 5%, 30 kΩ ROHM Semiconductor MCR10EZPJ303 10 1 R3 RES, SMD, 0603, 1/8 W, 5%, 10 kΩ ROHM Semiconductor MCR03EZPJ103 11 1 R4 RES, SMD, 0805, 1/8 W, 5%, 4.7 kΩ ROHM Semiconductor MCR10EZPJ472 *IC is not shown above. Either BD9673EFJ or BD9876EFJ will be used. Please check IC label on backside of PCB. 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