Rohm BD9G101G Application Note

Parameter

Symbol

Limit

Unit

Conditions

MIN

TYP

MAX

Supply Voltage

BD9G1010G

VCC 6 -

42

V

Output Voltage / Current

BD9G101G

VOUT - 5 - V

*Set by R1 and R2

BD9G101G

IOUT - 0.5 - A

No.0000000015

BD9673EFJ Eval Board

BD9G101G Eval Board (Back)

GND

Vout

BD9G101G Eval Board (Front)

EN

VOUT

VCC

GND

ENABLE
H: Active
(ICOFF)
L: Inactive
(ICON)

ROHM Switching Regulator Solutions

Evaluation Board:
Step-down Switching Regulator
With Built-in Power MOSFET

BD9G101G (5V | 0.5A Output)

●Introduction

This application note will provide the steps necessary to operate and evaluate ROHM’s step-down switching regulator using the BD9G101G
evaluation boards. Board layout recommendations, operation procedures, application data and build of materials are provided.

●Description

This evaluation board has been developed for ROHM’s step-down switching regulator customers evaluating BD9G101G. While accepting a
wide power supply of 6-42V, a step down output of 1V-29V can be produced. The IC has an internal 800mohm Nch MOSFET (1A max) and
a fixed operating frequency range of 1.5MHz. A Soft Start circuit prevents in-rush current during startup along with UVLO (low voltage error
prevention circuit), OCP (over-current protection) 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

Industrial distributed power applications
Automotive and battery powered equipment

●Evaluation Board Operating Limits and Absolute Maximum Ratings

●Evaluation Board

Below is the evaluation board with the BD9G101G. Component selection and board layout guidelines are provided in the
BD9G101G datasheet.

1

Application Note

L1: 10uH

10uH

●Evaluation Board Schematic

Below is the evaluation board schematic for BD9G101G.

●Evaluation Board I/O

Below is the reference application circuit that shows the inputs (Vcc and EN) and the output (Vout @ 5V/0.5A)

●Evaluation Board Operation Procedures

Below is the procedure to operate the evaluation board

1. Connect GND to a GND pin on the evaluation board

2. Connect Vcc to the VCC_pin. This will provide Vcc to the Vcc pin of the IC
i. Note: EN pin is pulled HIGH as default. EN needs to be set to LOW for IC operation.

3. Output voltage can be measured from the VOUT_pin on the evaluation board. Output current can be measured with a

proper load at VOUT.

Page 2 of 8

Application Note

●Reference Graphs Application Data for BD9G101G

Below graphs show efficiency, frequency response and load characteristics of the BD9G101G eval board.

Page 3 of 8

Application Note

Page 4 of 8

Application Note

Page 5 of 8

Application Note

 Note: Feed-forward capacitor Csp is not populated on the BD9G101G evaluation board. The capacitor is recommended

for designs requiring improved phase margin and transient response.

●Evaluation Board Layout Guidelines

Below are the guidelines that have been followed and recommended for BD9G101G designs.

Page 6 of 8

Application Note

Item

Qty

Ref

Description

Manufacturer

Part Number

Digikey P/N

1 1 CIN1

CAP CER 4.7UF 50V Y5V 1206

Murata

GRM31CF51H475ZA01L

490-1828-1-ND

2

1

CIN2

DIODE TVS 30V 400W UNI 5%
SMA

Littlefuse

SMAJ30A

SMAJ30ALFTR-ND

3 1 CO2

CAP CER 10UF 10V 10% X5R
1206

Murata

GRM31CR61A106KA01L

490-1820-2-ND

4 1 CBST

CAP CER 0.015UF 50V 10% X7R
0603

Murata

GRM188R71H153KA01D

490-1514-1-ND

5 1 D1

DIODE SCHOTTKY 60V 2A PMDU

ROHM

RB060M-60TR

RB060M-60CT-ND

6 1 SW1

SWITCH SLIDE SPDT 30V.2A PC
MNT

E-Switch

EG1218

EG1903-ND

7 1 R1

RES 68.0K OHM 1/8W 1% 0805
SMD

Yageo

RC0805FR-0768KL

311-68.0KCRCT-ND

8 1 R2

RES 12.0K OHM 1/8W 1% 0805
SMD

Yageo

RC0805FR-0712KL

311-12.0KCRCT-ND

9 1 LX

INDUCT 10uH SOD-106

TOKO

DEM4518C

1235AS-H-100M

-

10 1 U1

5V, 0.5A Step-down SW Reg w/
FET

ROHM

BD9G101G

-

●Evaluation Board BOM

Below is a table with the build of materials. Part numbers and supplier references are provided.

Page 7 of 8

Application Note

Page 8 of 8