BD9B301MUV-EVK-101 - ROHM SEMICONDUCTOR

EVK User’s Manual

OCT 2017

Introduction

This application note will provide the steps necessary to operate

and evaluate ROHM’s synchronous buck DC/DC converter

using the BD9B301MUV-EVK-101 evaluation board. Component

selection, board layout recommendations, operating procedures,

and application data are provided.

Description

This evaluation board has been specically developed to evaluate

ROHM’s BD9B301MUV synchronous buck DC/DC converter with

integrated 32mΩ Pch high-side and Nch low-side MOSFETs.

Features include 3.3V output from 2.7V to 5.5V input and variable

switching frequency: 1MHz (FREQ pin connected to VIN) or 2MHz

(FREQ pin connected to Ground). Multiple protection cricuits are

also buil in, including a xed soft start circuit that prevents inrush

current during startup, UVLO (Under Voltage Lock Out), and TSD

(Thermal Shutdown).

ROHM Switching Regulator Solutions

Evaluation Board: Synchronous Buck

Converter Integrated FET

BD9B301MUV-EVK-101 (3.3 | 3A Output)

An EN pin allows for simple ON/OFF control of the IC to reduce

standby current consumption, while a MODE pin enables users

to select Fixed Frequency PWM mode or Deep SLLM control that

automatically switches between modes.

Applications

• Step-Down Power Supplies for DSPs, FPGAs,

Microcontrollers, and more

• Laptop PCs/Tablet PCs/Servers

• LCD TVs

• Storage Devices (HDDs/SSDs)

• Printers, OA Equipment

• Entertainment Devices

• Distributed and Secondary Power Supplies

Evaluation Board Operating Limits and Absolute Maximum Ratings

Parameter Symbol

Limit

Unit Conditions

MIN TYP MAX

Supply Voltage

BD9B301MUV VCC 2.7 ─ 5.5 V

Output Voltage/Current

BD9B301MUV

VOUT ─3.3 ─V

IOUT ─ ─ 3 A

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Evaluation Board

Board Schematic

Figure 1: Evaluation Board for the BD9B301MUV

Figure 2: BD9B301MUV-EVK-101 Evaluation Board Schematic

VOUT=0.8*(R4+R5)/R5

22µF

10%

6.3V

1210

C10

180pF

50V

0603

51k

1/10W

0603

0.1µF

10%

16V

0603

0.1µF

10%

16V

0603

0.1µF

10%

16V

0603

10µF

10%

10V

1206

P48MA6.8A

DO-214A/C

5.8V

39.0A

C11

0603

DNP

74437349015

SMT_6P6x6P6

20%

1.5µH

TP1

PGD

AGND

BD9B301MUV

VQFND16V3030

TP2

TP3

4 6

9 17

PGND

87224-3

FREQ FREG

MODE

PVIN

AVIN

VIN

AVIN

EPAD

BOOT

1/10W

0603

R3 1k B

OUT

SST2222AT116

SOT23

CR1

SML-310MTT86

LED_0603

140

1/10W

0603

100k

1/10W

0603

PGD_LED

PGD_QC

PGD_QB

AVIN

160k

1/10W

0603

22µF

10%

6.3V

1210

0805

DNP

1206

DNP

VOUT

TP4

TP5

(OUTPUT: 3.3V@3A)

0603

DNP

(INPUT: 2.7-5.5 VDC)

BD9B301MUV EVM Jumper Positions

Reference

Designator Position Description

2-1 Enable U1

2-3 Disable U1

2-1 Set switching frequency of U1 is 1.0MHz

2-3 Set switching frequency of U1 is 2.0MHz

2-1 Set operation mode of U1 is xed frequency PWM mode

2-3 Set operation mode of U1 is automatically switched between

the Deep-SLLM control and xed frequency PWM mode

Note:

1. 0.8V=< VOUT =V 0.8*VIN

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Board I/O

Operating Procedure

Below is a reference application circuit that shows the inputs VIN, Enable, FREQ and MODE and the output VOUT.

PVIN

AVIN

10µF 0.1µF

1.0µH

BD9B301MUV

22µF x 2

PGD

BOOT

CBOOT

MODE

CSS FREQ

PGND

AGND

VOUT

CFB

VIN

Enable

MODE

FREQ

1. Connect the power supply’s GND terminal to GND test point TP3 on the evaluation board.

2. Connect the power supply’s VCC terminal to VIN test point TP2 on the evaluation board. This will provide VIN to the IC

U1. Please note that VCC should be in the range from 2.7V to 5.5V.

3. Set the operating mode by changing the position of shunt jumper J3 (If Pin2 is connected to Pin1, the MODE pin of IC

U1 will be pulled high and IC U1 will operate in Fixed frequency PWM mode, otherwise the MODE pin of IC U1 will be

pulled low and IC U1 will operate by automatically switching between Deep-SLLM control and xed frequency PWM

mode).

4. Set the switching frequency by changing the position of shunt jumper J2 (If Pin2 is connected to Pin1, the FREQ pin

of IC U1 will be pulled high and IC U1 will switch frequency to 1.0MHz, otherwise the FREQ pin of IC U1 will be pulled

low and the the frequency will be switched to 2.0MHz).

5. Check if shunt jumper J1 is the ON position (Connect Pin 2 to Pin 1, the EN pin of IC U1 is pulled high as a default).

6. Connect the electronic load to TP4 and TP5. Do not turn on the load.

7. Turn on the power supply. The output voltage VOUT (+3.3V) can be measured at the test point TP4. Now turn on the

load. The load can be increased up to 3A MAX.

Figure 2: BD9B301MUV-EVK-101 Evaluation Board I/O

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Reference Application Data

The following are graphs of the hot plugging test, quiescent current, efciency, load response, and output voltage ripple response of

the BD9B301MUV-EVK-101 evaluation board.

Fig 4: Hot Plug-in Test with Zener Diode

P4SMA6.8A, VIN=5.5V, VOUT=3.3V,

IOUT=3A, FREQ=L, MODE=L

Fig 5: Circuit Current vs. Power Supply

Voltage Characteristics (Temp=25ºC,

FREQ=L, MODE=L)

Fig 6: Electric Power Conversion Rate

(VOUT=3.3V, FREQ=L, MODE=L)

Fig 9: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0, FREQ=L, MODE=L)

Fig 7: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0 → 3A, FREQ=L, MODE=L)

Fig 10: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A, FREQ=L, MODE=L)

Fig 8: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A → 0, FREQ=L, MODE=L)

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Typical Performance Data - continued

Fig 11: Hot Plug-in Test with Zener Diode

P4SMA6.8A, VIN=5.5V, VOUT=3.3V,

IOUT=3A, FREQ=L, MODE=H

Fig 12: Circuit Current vs. Power Supply

Voltage Characteristics (Temp=25ºC,

FREQ=L, MODE=H)

Fig 13: Electric Power Conversion Rate

(VOUT=3.3V, FREQ=L, MODE=H)

Fig 14: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0 → 3A, FREQ=L, MODE=H)

Fig 16: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0, FREQ=L, MODE=H)

Fig 15: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A → 0, FREQ=L, MODE=H)

Fig 17: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A, FREQ=L, MODE=H)

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Typical Performance Data - continued

Fig 18: Hot Plug-in Test with Zener Diode

P4SMA6.8A, VIN=5.5V, VOUT=3.3V,

IOUT=3A, FREQ=H, MODE=L

Fig 19: Circuit Current vs. Power Supply

Voltage Characteristics (Temp=25ºC,

FREQ=H, MODE=L)

Fig 20: Electric Power Conversion Rate

(VOUT=3.3V, FREQ=H, MODE=L)

Fig 21: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0 → 3A, FREQ=H, MODE=L)

Fig 23: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0, FREQ=H, MODE=L)

Fig 22: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A → 0, FREQ=H, MODE=L)

Fig 24: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A, FREQ=H, MODE=L)

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Typical Performance Data - continued

Fig 25: Hot Plug-in Test with Zener Diode

P4SMA6.8A, VIN=5.5V, VOUT=3.3V,

IOUT=3A, FREQ=H, MODE=H

Fig 26: Circuit Current vs. Power Supply

Voltage Characteristics (Temp=25ºC,

FREQ=H, MODE=H)

Fig 27: Electric Power Conversion Rate

(VOUT=3.3V, FREQ=H, MODE=H)

Fig 28: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0 → 3A, FREQ=H, MODE=H)

Fig 30: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=0, FREQ=H, MODE=H)

Fig 29: Load Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A → 0, FREQ=H, MODE=H)

Fig 31: Output Voltage Ripple Response Characteristics

(VIN=5V, VOUT=3.3V, IOUT=3A, FREQ=H, MODE=H)

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Evaluation Board Layout Guidelines

In the step-down DC/DC converter, a large pulse current ows through two loops. The rst loop is the one into which current ows

when the High-Side FET is turned ON. The ow starts from the input capacitor CIN, runs through the FET, inductor L, and output

capacitor COUT, then back to the GND of CIN via the GND of COUT. In the second loop current ows when the Low-Side FET is turned

on. The ow starts from the Low-Side FET, runs through the inductor L and output capacitor COUT, then back to the GND of the Low-

Side FET via the GND of COUT. We recommend routing these two loops as thick and as short as possible to minimize noise and

improve efciency. The input and output capacitors should be connected directly to the GND plane. Please note that the PCB layout

has a large inuence on the DC/DC converter in terms of heat generation, noise, and efciency.

Accordingly, when designing the PCB layout please consider the following points.

• Connect an input capacitor as close as possible to the IC PVIN terminal on the same plane as the IC.

• If there is any unused area on the PCB, provide a copper foil plane for the GND node to assist heat dissipation from the IC and

the surrounding components.

• Switching nodes such as SW are susceptible to noise due to AC coupling with other nodes. Therefore, route the coil pattern as

thick and as short as possible.

• Ensure that lines connected to FB are far from the SW nodes.

• Place the output capacitor away from the input capacitor in order to avoid the effects of harmonic noise from the input.

Power Dissipation

When designing the PCB layout and peripheral circuitry, sufcient consideration must be given to ensure that the power dissipation is

within the allowable dissipation curve.

VOUT

COUTCIN

MOSFET L

VIN

Fig 32: Current Loops of Buck Regulator System

Fig 33: Thermal Derating Characteristics

1. 4-layer board (surface heat dissipation copper foil 5505 mm2)

(Copper foil laminated on each layer)

θJA= 47.0°C/W

2. 4-layer board (surface heat dissipation copper foil 6.28 mm2)

(Copper foil laminated on each layer)

θJA= 70.62°C/W

3. 1-layer board (surface heat dissipation copper foil 6.28 mm2)

θJA= 201.6°C/W

4. IC only

θJA= 462.9°C/W

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

Fig 34: BD9B301MUV-EVK-101 Board PCB layout

Application Circuit Component Selection

Inductor (L)

The inductance signicantly depends on the output ripple current. As shown by following equation, the ripple current decreases as the

inductor and/or switching frequency increases.

Where f=Switching Frequency, L=Inductance, and ΔL=Inductor Ripple Current.

As a minimum requirement, the DC current rating of the inductor should be equal to the maximum load current plus half of the inductor

ripple current as shown by the equation below.

∆IL = (VIN -VOUT) x VOUT

L x VIN x f

ILPEAK = IOUTMAX + ∆IL

∆IL = (VIN -VOUT) x VOUT

L x VIN x f

ILPEAK = IOUTMAX +

∆I

EVK User’s Manual

Eval Board: Synchronous Buck Converter Integrated FET

OCT 2017

No. Qty. Reference Description Manufacturer Part No.

1 1 CR1 LED 570NM GREEN WTR CLR 0603 SMD ROHM SML-310MTT86

2 1 C1 CAP CER 10µF 10V 10% X5R 1206 Murata GRM319R61A106KE19D

3 3 C2, C3, C4 CAP CER 0.1µF 16V 10% X7R 0603 Murata GRM188R71C104KA01D

4 2 C5, C6 CAP CER 22µF 6.3V 10% X5R 1210 Murata GRM32DR60J226KA01L

51 C10 CAP CER 180PF 50V 5% NP0 0603 Murata GRM1885C1H181JA01D

6 1 D1 DIODE TVS 400W 6.8V UNI 5% SMD Littlefuse Inc. P4SMA6.8A

7 3 J1, J2, J3 CONN HEADER VERT .100 3POS 15AU TE Connectivity 87224-3

8 1 L1 INDUCTOR WW 1.5µH 8A SMD Wurth 74437349015

9 1 Q1 TRANSISTOR NPN 40V 0.6A SOT-23 ROHM SST2222AT116

10 1 R1 RES 140 OHM 1/10W 1% 0603 SMD ROHM MCR03ERTF1400

11 1 R2 RES 100K OHM 1/10W 5% 0603 SMD ROHM MCR03ERTJ104

12 1 R3 RES 1K OHM 1/10W 5% 0603 SMD ROHM MCR03ERTJ102

13 1 R4 RES 160K OHM 1/10W 1% 0603 SMD ROHM MCR03ERTF1603

14 1 R5 RES 51K OHM 1/10W 1% 0603 SMD ROHM MCR03ERTF5102

15 3TP1, TP2, TP4 TEST POINT PC MULTI PURPOSE RED Keystone Electronics 5010

16 2 TP3, TP5 TEST POINT PC MULTI PURPOSE BLK Keystone Electronics 5011

17 1 U1 DCDC Converter ROHM BD9B301MUV

18 3 Shunt jumper for header J1, J2, J3 (item #7),

CONN SHUNT 2POS GOLD W/HANDLE TE Connectivity 881545-1

Evaluation Board BOM

Below is a table showing the bill of materials. Part numbers and supplier references are also provided.

Notice

1. The information contained herein is subject to change without notice.

2. Before you use our Products, please contact a sales representative and verify the latest specications.

3. Although ROHM is continuously working to improve product reliability and quality, semiconductors can break

down and malfunction due to various factors.

Therefore, in order to prevent personal injury or re arising from failure, please take safety measures such as

complying with the derating characteristics, implementing redundant and re prevention designs, and utilizing

backups and fail-safe procedures. ROHM shall have no responsibility for any damages arising out of the use

of our Poducts beyond the rating specied by ROHM.

4. Examples of application circuits, circuit constants and any other information contained herein are provided

only to illustrate the standard usage and operations of the Products. The peripheral conditions must be taken

into account when designing circuits for mass production.

5. The technical information specied herein is intended only to show the typical functions and examples of

application circuits for the Products. ROHM does not grant you, explicitly or implicitly, any license to use

or exercise intellectual property or other rights held by ROHM or any other parties. ROHM shall have no

responsibility whatsoever for any dispute arising out of the use of such technical information.

6. The Products specied in this document are not designed to be radiation tolerant.

7. When using our Products in applications requiring a high degree of reliability (as exemplied below), please

contact and consult with a ROHM representative : transportation equipment (i.e. cars, ships, trains), primary

communication equipment, trafc lights, re/crime prevention, safety equipment, medical systems, servers,

solar cells, and power transmission systems.

8. Do not use our Products in applications requiring extremely high reliability, such as aerospace equipment,

nuclear power control systems, and submarine repeaters.

9. ROHM shall bear no responsibility for any damages or injury arising from non-compliance with the recommended

usage conditions and specications contained herein.

10. ROHM has used reasonable care to ensure the accuracy of the information contained in this document.

However, ROHM does not warrants that such information is error-free, and ROHM shall have no responsibility

for any damages arising from any inaccuracy or misprint of such information.

11. Please use the Products in accordance with any applicable environmental laws and regulations, such as the

RoHS Directive. For more details, including RoHS compatibility, please contact a ROHM sales ofce. ROHM

shall bear no responsibility for any damages or losses resulting from non-compliance with any applicable laws

or regulations.

12. When providing our Products and technologies contained in this document to other countries, you must abide

by the procedures and provisions stipulated in all applicable export laws and regulations, including without

limitation the US Export Administration Regulations and the Foreign Exchange and Foreign Trade Act.

13. This document, in part or in whole, may not be reprinted or reproduced without the prior consent of ROHM.

Notes

Thank you for your interest in ROHM products.

Please contact us for additional information and product catalogs.

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