ROHM Switching Regulator Solutions
Evaluation Board:
Step-down Switching Regulator
With Built-in Power MOSFET
BD9673EFJ / BD9876EFJ (5V | 1.5A / 3.0A 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.
No.0000000013
●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
Supply Voltage
BD9673EFJ
BD9876EFJ
Output Voltage / Current
BD9673EFJ
BD9876EFJ
BD9673EFJ
BD9876EFJ
VOUT
VOUT
IOUT
IOUT
1*
1*
-
-
-
-
-
-
VCCx0.7
VCCx0.7
1.5
3
V
V
A
A
*Restricted by minimum on pulse
typ. 200ns
*Restricted by minimum on pulse
typ. 200ns
VCC
VCC
7
7
-
-
45
45
V
V
Symbol
MIN
TYP
MAX
Unit
Conditions
●Evaluation
Board
Below is the evaluation board with the BD9673EFJ. BD9876EFJ eval board uses the same components and board layout
Vout
GND
GND
Vcc
BD9673EFJ Eval Board
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
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Application Note
●Reference
Graphs Application Data for BD9673EFJ
Below graphs show efficiency, frequency response and load characteristics of the BD9673EFJ eval board.
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Application Note
●Reference
Graphs Application Data for BD9876EFJ
Below graphs show efficiency, frequency response and load characteristics of the BD9876EFJ eval board.
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Analogue and Mixed Signal
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