BD9470AFM [ROHM]

BD9470AFM是白色LED用高效率驱动器，适用于大屏幕液晶驱动器。BD9470AFM内置了可向光源（LED串联连接的阵列）提供适当电压的DCDC转换器。BD9470AFM内置了过电压保护（OVP: over voltage protection）、过电流检测（OCP: over current limit protection of DCDC）、短路电路保护（SCP: short circuit protection）、开路保护（open detection of LED string）等针对异常状态的保护功能。因此，可在更宽的输出电压条件及负载条件下使用。;


型号：	BD9470AFM
厂家：	ROHM
描述：	BD9470AFM是白色LED用高效率驱动器，适用于大屏幕液晶驱动器。BD9470AFM内置了可向光源（LED串联连接的阵列）提供适当电压的DCDC转换器。BD9470AFM内置了过电压保护（OVP: over voltage protection）、过电流检测（OCP: over current limit protection of DCDC）、短路电路保护（SCP: short circuit protection）、开路保护（open detection of LED string）等针对异常状态的保护功能。因此，可在更宽的输出电压条件及负载条件下使用。驱动 CD 电路保护驱动器转换器
文件：	总38页 (文件大小：1783K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

Datasheet

LED driver series for LCD back light

White LED driver for medium sized

and large sized LCD back light

BD9470AEFV・BD9470AFM

●General Description

●Key Specifications

BD9470AEFV and BD9470AFM are high efficiency

driver for white LED. They are designed for large sized

LCD. BD9470AEFV and BD9470AFM are built-in

DCDC converter that supply appropriate voltage for

light source.

BD9470AEFV and BD9470AFM are also built-in

protection function for abnormal state such as OVP:

over voltage protection, OCP: over current limit

protection of DCDC, SCP: short circuit protection, open

detection of LED string.



VCC supply Voltage range:

LED minimum output current:

LED maximum output current:

DCDC oscillation frequency: 150KHz(RT=100Kohm)

Operation circuit current:

9.0V～35.0V

40mA

250mA

6mA(typ.)

-40℃～85℃

Operating temperature range:

●Applications

■ LED driver for TV, monitor and LCD back light

Thus they are used for conditions of large output

voltage and load conditions.

●Package

●Features

W (Typ.) x D(Typ.) x H(Max.)

18.50mm x 9.90mm x 2.41mm

9.70mm x 6.40mm x 1.00mm



6ch LED constant current driver

LED maximum output current 250mA

Individual PWM dimming modulation allowed for

HSOP-M28

HTSSOP-B28

LEDs



±2% LED current accuracy (when each LED is set

to 130mA)

 Built-in LED feedback voltage automatic adjustment

circuit according to LED current

 Built-in start-up circuit independent of PWM light

modulation

 built-in VOUT・FB voltage maintenance function

when PWM=Low（0%）

 Built-in LED current stabilization circuit while

scanning operation is performed

 Built-in VOUT discharge circuit while shutdown

 Built-in LED protection (OPEN / SHORT protection)

Figure 1. HSOP-M28



Individual detection and individual LED OFF for

both open and short circuit

 Adjustable LED short-circuit protection threshold

 PWM-independent LED protection

 VOUT over voltage protection (OVP) and reduced

voltage protection (SCP) circuit



Built-in failure indication function

 Built-in ISET pin short-circuit protection circuit

●Typical Application Circuit

VIN

ISET

PWM1

PWM2

PWM3

PWM4

PWM5

DCDC_GND

PWM

Figure 2. HTSSOP-B28

REG58

PWM6

VCC

STB

GND

STB

FAIL

OVP

LSP

LED6

LED5

LED4

LED_GND

UVLO

LED1

LED2

LED3

Figure 3. Typical Application Circuit

○Product structure：Silicon monolithic integrated circuit ○This product is not designed protection against radioactive rays

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1. Specification for BD9470AEFV・BD9470AFM

●Absolute Maximum Ratings (Ta=25°C)

Parameter

Symbol

Rating

unit

OVP Detect Voltage (DCDC Stop)

LED1~6 pin voltage

VCC

-0.3~36

-0.3~40

-0.3~36

LED1~6

STB・FAIL・UVLO・OVP pin voltage

STB,FAIL,UVLO,OVP

ISET・FB・SS・

CS・N・REG58・RT pin voltage

ISET・FB・SS・CS・N・REG58・RT

-0.3~7

PWM1~6・LSP

-0.3~16

5208

Power dissipation (HSOP-M28)*1

Power dissipation (HTSSOP-B28)*2

Operating temperature range

Storage temperature range

Maximum junction temperature

℃

4700

Topr

Tstg

Tjmax

-40～+85

-55～+150

+150

℃

^*1Decreases -41.7mW/°C at Ta=25°C or higher (When mounting a four-layer 70.0mmx70.0mmx1.6mm board)

^*2Decreases -37.6mW/°C at Ta=25°C or higher (When mounting a four-layer 70.0mmx70.0mmx1.6mm board)

●Recommended Operating Ratings

Parameter

Symbol

Rating

unit

Supply voltage

VCC

ILED_MIN

ILED_MAX

VLSP

9.0 ～ 35.0

mA*1

mA*1*2*3

LED1-4 pin minimum output current

LED1-4 pin maximum output current

LSP input voltage range

250

0.3～2.5

100 ～ 500

DC/DC oscillation frequency

fsw

kHz

Min. on-duty for PWM light modulation

PWM_MIN

μS

temperature. To avoid this problem, design the board with thorough consideration given to heat radiation measures.

*3 The LED current can be set up to 250mA

The amount of current per channel

If LED makes significant variations in its reference voltage Vf, the driver will increase power dissipation, resulting in a rise in package

● Pin Configuration ( TOP VIEW )

●Outline Dimension Diagrams/Sign Diagrams

ISET

PWM1

PWM2

PWM3

PWM4

PWM5

PWM6

LOT No.

DCDC_GND

REG58

BD9470AFM

GND

FAIL

VCC

STB

OVP

LSP

LED6

UVLO

LED1

LED2

LED3

LED5

LED4

LED_GND

LOT No.

1.REG58

28.VCC

27.STB

26.LSP

2.CS

3.N

4.DCDC_GND

5.RT

25.UVLO

24.LED1

23.LED2

22.LED3

21.LED_GND

20.LED4

19.LED5

18.LED6

17.OVP

16.FAIL

15.GND

BD9470AEFV

6.FB

7.SS

8.ISET

9.PWM1

10.PWM2

11.PWM3

12.PWM4

13.PWM5

14.PWM6

Figure 5. Outline Dimension Diagrams/Sign Diagrams

Figure 4. Pin Configuration（TOP VIEW）

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Contents

1. Specification for BD9470AEFV・BD9470AFM

●Absolute Maximum Ratings

P2～P9

●Recommended Operating Ratings

●Pin Configuration

●Outline Dimension Diagrams/Sign Diagrams

●Electrical Characteristics

●Pin Numbers, Names, and Functions

●External Component Recommended Range

●Internal Equivalent Circuit Diagrams

●Block Diagram

P4,P5

●Characteristic date

P8,P9

2. Understanding BD9470AEFV・BD9470AFM

●Pin Functions

P10～P12

3. Application of BD9470AEFV・BD9470AFM

P13～P32

3.1 BD9470AEFV, BD9470AFM examination for application

●Start-up and SS capacity setting explanation

●The setting of REG58 capacity and shutdown procedure

●VCC series resistance setting procedure

●The necessity for holding output voltage and FB voltage while PWM=Low

●Explanation of VOUT（OVP） voltage holding function when PWM=Low

●FB current Source mode・Sink/Source mode

●LED Current setting

P13～P27

P13,P14

P15

P16

P17,P18

P19,P20

P21,P22

P23

●DC/DC converter drive frequency setting

●UVLO setting procedure

P23

P24

●OVP/SCP setting method

P25

●LSP setting procedure

P26

●Timer latch function

P27

3.2 Selection of DCDC components

●OCP setting procedure/DCDC component current tolerance selection procedure

●Selection of Inductor L

P28～P30

P28,P29

P30

●Selection of switching MOSFET transistors

●Selection of rectifier diodes

P30

3.3 Timing chart

P31

P32

3.4 List of protection function

4. Caution on use

P33

P34

P35

5. Ordering Information

6. Revision history

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●Electrical Characteristics (unless otherwise specified, Ta = 25°C, VCC=24V )

Specification

Parameter

【Whole Device】

Symbol

unit

Condition

Min

Typ

Max

Operation Circuit

Icc

－

5.5

8.5

mA STB=3V, PWM1-6=3.3V

Standby current

IST

μA

STB=0V

【UVLO Block】

Operating voltage (VCC）

Hysteresis voltage （VCC）

UVLO release voltage

UVLO hysteresis voltage

UVLO pin leakage current

【DC/DC Block】

VUVLO_VCC

VUHYS_VCC

VUVLO_U

6.5

150

2.88

250

-2

7.5

300

3.00

300

8.5

600

3.12

350

VCC=SWEEP UP

mV VCC=SWEEP DOWN

VUVLO=SWEEP UP

mV VUVLO=SWEEP DOWN

VUHYS_U

UVLO_LK

μA

VUVLO=4V

Error amp. Reference voltage

(Min)

LEDx Terminal ILEDx

40mA

LEDx Terminal ILEDx

130mA

VLED

0.36

0.428

142.5

0.40

0.450

150

0.44

0.472

157. 5

Error

amp.

basic

voltage

(ILED=130mA)

Oscillation frequency

FCT

KHz RT=100kohm

Max. duty cycle of output N

RT short protection range

NMAX_DUTY

RT_DET

RONSO

RONSI

RT=100kohm

-0.3

1.5

VRT×90%

RT=SWEEP DOWN

On resistance on N pin source

side

On resistance on N pin sink side

RT pin voltage

1.5

VRT

1.5

-2.0

3.70

-100

100

RT=100kohm

SS pin source current

Soft start completion voltage

FB source current

ISSSO

-2.6

3.52

-115

-1.4

3.88

-85

μA

VSS=2V

VSS_END

IFBSO

SS=SWEEP UP

VLED=0V, VFB=1.0V

μA

VLED=5.0V(ALL_CH),

VFB=1.0V,VSS=4V

FB sink current

IFBSI

130

FB source mode

FB_SO_SS

FB_SOSI_SS

VCS

4.9

SS=SWEEP UP

SS pin input voltage range

FB sink/source mode

SS pin input voltage range

3.9

4.4

SS=SWEEP DOWN

Over current detect voltage

CS source current

372

400

428

mV CS=SWEEP UP

ICS

μA

VCS=0V

【DC/DC protection Block】

OVP Detect Voltage (DCDC

Stop)

VOVP

VOVP_CAN

VSCP

2.90

3.00

3.10

VOVP SWEEP UP

VOVP SWEEP DOWN

VOVP=4V

OVP protection timer release

Short protection detect voltage

OVP pin leakage current

VOVP-0.14 VOVP-0.1 VOVP-0.04

0.05

-2

0.1

0.15

OVP_LK

μA

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●Electrical Characteristics (unless otherwise specified, Ta = 25°C, VCC=24V)

Specification

Parameter

Symbol

unit

Condition

Min

Typ

Max

【LED Driver Block】

LEDｘ pin current accuracy1

LEDｘ pin current accuracy2

LEDｘ pin leakage current

ISET pin voltage

⊿ILED1

⊿ILED2

⊿ILED3

ILLED

-2

ILED=130mA

-2.5

-3.5

-0.8

1.3

2.5

3.5

0.8

1.7

ILED=150mA

ILED=250mA

STB=H,

LEDx=40V

PWMx=L,

LEDｘ pin current accuracy1

【LED protection Block】

ISET short circuit protection range

LEDｘSHORT protection voltage

VISET

1.5

RISET=30kΩ

ISET_DET

VLSP

-0.3

8.5

VISET×90%

9.5

ISET=SWEEP DOWN

LEDx=SWEEPUP,

LSP=OPEN

LSP pin resistive divider(Higher

RULSP

RDLSP

VOPEN

1860

540

3100

900

0.20

5580

kΩ

LSP=0V

1620

LSP=4V

LSP pin resistive divider(Lower R)

LEDｘ OPEN detect voltage

【REG58 BLock】

0.15

0.25

LEDx=SWEEP DOWN

REG58 output voltage 1

REG58 output voltage 2

REG58 max output current

REG58_UVLOdetect voltage

REG58_UVLO Hysteresis

REG58 Discharge current

【STB Block】

REG58_1

REG58_2

5.742

5.713

5.8

－

5.858

5.887

IO=0mA

IO=-15mA

| IREG58 |

STB=ON

REG58=SWEEP DOWN

STB=ON->OFF

REG58_TH

REG58_HYS

REG58_DIS

2.1

2.4

200

5.0

2.7

100

3.0

400

7.0

REG58=SWEEP DOWN

STB=ON->OFF REG58=4V

STB pin HIGH voltage

STBH

STBL

RSTB

0.8

STB=SWEEP UP

STB=SWEEP DOWN

VSTB=3.0V

STB pin LOW voltage

-0.3

600

STB pin Pull Down resistance

【PWM Block】

1000

1800

kΩ

PWMｘ pin HIGH voltage

PWMｘ pin LOW voltage

PWMｘ pin Pull Down resistance

【FAIL Block（OPEN DRAIN）】

FAIL Pin Ron

PWM_H

PWM_L

RPWM

1.5

-0.3

0.8

PWMｘ=SWEEP UP

PWMｘ=SWEEP DOWN

PWMｘ=3.0V

1200

2000

3600

kΩ

RFAIL

ILFAIL

250

-2

500

1000

VFAIL=1.0V

VFAIL=5V

FAIL Pin Leakage current

μA

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●Pin Numbers/Names/Functions

Pin No.

HSOP-M28 HTSSOP-B28

Pin Name

Symbol

Function

ISET

PWM1

PWM2

PWM3

PWM4

PWM5

PWM6

GND

LED current setting resistor connection pin

PWM light modulation signal input pin for LED1

PWM light modulation signal input pin for LED2

PWM light modulation signal input pin for LED3

PWM light modulation signal input pin for LED4

PWM light modulation signal input pin for LED5

PWM light modulation signal input pin for LED6

Ground pin for analog block

FAIL

Error detection output pin

OVP

Overvoltage protection detection pin

LED output 6

LED6

LED5

LED4

LED_GND

LED3

LED2

LED1

UVLO

LSP

LED output 5

LED output 4

Ground pin for LED

LED output 3

LED output 2

LED output 1

Detection pin for Under voltage Lockout prevention

LED short-circuit protection voltage setting pin

Enable pin

STB

VCC

Power supply pin

REG58

5.8V regulator output pin / Shutdown timer pin

DC/DC output current detection pin

OCP detection pin

DCDC_GND

DC/DC switching output pin

DC/DC GND pin

DCDC Drive frequency setting connection pin

Error Amp output pin

Slow start/

LED protection masking time setting pin

●External Component Recommended Range

Parameter

Symbol

Specification

unit

VCC pin connecting capacity

VCC pin connecting resistance

REG58 pin connecting capacity

Soft start setting capacity

0.1 ～ 100

0 ～ *1

CVCC

RVCC

C_REG

CSS

μF

kΩ

μF

kΩ

1.0～470

0.001～1.0

30～150

RT pin connection resistance range

RRT

ISET pin connecting resistance range

12.16～75

RISET

The operating conditions listed above are constants for the IC alone. To make constant setting with practical set devices, utmost attention should be paid.

*1 Please refer to 【3.2 function explanatiob and selection of external components for thes election of VCC

series resistance.

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●Internal Equivalent Circuit Diagrams

REG58 / N / CS / DCDC_GND

REG58

DCDC_GND

OVP

ISET

OVP

100k

ISET

STB

FAIL

UVLO

STB

UVLO

FAIL

500

LED1-6/LED_GND

PWM

LSP

LED1-6

PWM1-6

100k

LSP

3.1M

100k

900k

LED_GND

Figure 6. Internal Equivalent Circuit Diagrams

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● Block Diagram

CREG

COUT

REG58

UVLO

OS DET

OVP

VCC

VCC STB

OVP

UVLO

(VCC)

VCC

UVLO

TSD

SCP

Timer

LOGIC

VREG

FAIL

PWM COMP

Driver

Control

Logic

OSC

Current

Sence

REG58

Css

DCDC_GND

Use at

At sink source mode

SS FB

Clamp

AGND

ERR AMP

SS_END

Rpc

Cpc

LED1

LED2

Current driver

LED3

LED4

LED5

PWM1

PWM2

PWM3

PWM4

PWM5

PWM6

LED6

1.5V

LEDGND

ISET

Open-Short

Detect

SS_END

0.9V

LSP

OSDET

Figure 7. Block Diagram

●Characteristic date(reference date)

7.0

6.5

6.0

5.5

5.0

VCC[V]

Figure 8. ICC[mA] vs VCC[V]

Figure 9. REG58[V] vs VCC[V]

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140

138

136

134

132

130

128

126

124

122

120

160

120

-40

-80

-120

-160

-40

-20

Temp[℃]

LEDx[V]

Figure 11. IFB[uA] vs LEDx[V]

( @ILED=130mA)

Figure 10. ILED[mA] vs Temp[℃]

1000

100

1000

100

RRT[kohm]

1000

RISET[kohm]

Figure 13. FCT [kHz] vs RRT[kohm]

Figure 12. ILEDx[mA] vs RISET[kohm]

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2. Understanding BD9470AEFV・BD9470AFM

●Pin Functions

○ISET （HTSSOP-B28:8PIN/HSOP-M28：1PIN）

The ISET pin is a resister value of output current setting. The output current ILED vary in inverse proportion to resister

value. The relation of the output current ILED and ISET pin connecting resistor RISET are as bellow.

3000

R_ISET

[kΩ]ꢀꢀ

I_LED[mA]

However, current setting range is from 40mA to 150mA.

And the setting of ISET resistor is bellow at using 150mA to 250mA.

R_ISET= 2653× ( I_LED[mA] )^−0.9753[kΩ]ꢀꢀ

ILED(mA)

150

160

170

180

190

200

210

220

230

240

250

RSET(kohm)

20.00 18.80 17.72 16.76 15.90 15.12 14.42 13.78 13.19 12.66 12.16

For a setting example, please refer to ‘3.1 application explanation / LED current setting’.

When the RISET is shorted and the ISET pin is grand shorted, the LED current is OFF and the FAIL=OPEN(abnormal

signal) to prevent flowing a large current to LED pin when it becomes less than VISET×0.90V(typ).

When the ISET pin back to normal state the LED current return to former system, too and the FAIL=GND(normal signal).

It prepare automatically to suitable LED feedback voltage that can output LED current set by ISET pin.

In short LED feedback voltage is dropped when the LED current is small and the IC heating is held automatically.

In case of a large current is needed, raise the LED pin feedback voltage. And it adjust automatically to LED pin voltage that

can be flow large LED current.

The calculation is as below.

VLED = 3.462× I [A] [V ]ꢀꢀ

LED

The LED feedback voltage (VLED) is clamped to 0.4V(typ.) when the LED current (ILED) is less than 115.6mA.

○PWM1-6 （HTSSOP-B28:9,10,11,12,13,14PIN

HSOP-M28：2,3,4,5,6,7PIN）

The ON/OFF pin for LED driver. Light can be modulated by changing the duty cycle through the direct input of a PWM

light modulation signal in each PWM pin.

The high and low voltage levels of PWM_x pins are as listed in the table below.

State

PWMxvoltage

LED ON state

PWMx=1.5V~15.0V

LED OFF state

PWMx=‐0.3V～0.8V

The sequence of STB/PWM for start-up, please input PWM signal before STB or the same timing STB=PWM=ON.

○GND （HTSSOP-B28:15PIN

HSOP-M28：8PIN）

IC internal analog GND pin.

○FAIL （HTSSOP-B28:16PIN

HSOP-M28：9PIN）

FAIL signal output pin （OPEN DRAIN）.Internal NMOS will become OPEN while abnormal is detected.

State

Normal

FAILoutput

GND

Abnormal（After Timer Latch）

OPEN Level

○OVP （HTSSOP-B28:17PIN

HSOP-M28：10PIN）

The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage. If over voltage

is detected, the OVP pin will stop the DC/DC converter conducting step-up operation. If Vout was increased by abnormality,

timer is set while OVP＞2.9V(typ.).when it comes to OVP＞3.0V, timer will ON at the same time and to stop DCDC.

Although Counter will be stopped when OVP＜2.9V during counting time, in the state of OVP>2.9V, when internal counter

completed 2¹⁸count （262152 count）, the system will be latched.

When the short circuit protection (SCP) function is activated, the DC/DC converter will stop operation, and then the timer

will start counting, after 2¹⁶count（65536 count）, DCDC and LED driver will stop and latch.

The OVP pin is of the high impedance type and involves no pull-down resistor, resulting in unstable potential in the

open-circuit state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider or

otherwise. OVP pin will be feedback pin when PWM=L. Also, this pin will hold OVP voltage at that time when switch PWM

= H to L.

For setting example, refer to information in“3.4 Selection of External Components-OVP/SCP setting procedure

OVP Voltage keep internal IC with PWM=Low timing, and VOUT voltage can hold by using copied OVP voltage while

PWM=Low.（The OVP keep voltage range is 0~3V, 30steps）.For setting example, refer to information in “3.2 Selection of

External Components”, “Explanation of VOUT（OVP） voltage holding function when PWM=Low”

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○LED1-6 （HTSSOP-B28:18,19,20,22,23,24PIN

HSOP-M28：11,12,13,15,16,17PIN）

LED constant current output pins. Current value setting can be made by connecting a resistor to the ISET pin.

For the current value setting procedure, refer to the description of “ISET pin”.

If any of the LED pins is put in an abnormality state (short circuit mode, open circuit mode, ground short mode), the

relevant protection function will be activated.

・LED pin short circuit protection function ( LSP)

When any LED is in short state (more than LED=9.0V(typ)) the LED SHORT is detected.

After abnormal detection, the timer count starts. The LED that is abnormal detection after 2¹⁶count is stopped and other

LED driver operates normally.

・LED pin open circuit protection function (LOP)

If any of the LED pins becomes open-circuited (0.2V (Typ.) or less), LED_OPEN will be detected. When this error is

detected, the timer will start counting, When it completes counting the preset period of time, only LED driver that detected

the error will stop operation and other LED driver will conduct normal operation.

・LED GND_SHORT protection function

When any LED pin is GND shorted the LED pin becomes less than 0.20V and the pin is latched because of LED_OPEN

detection. After that, the LED pin is pull upped by inner supply but it continues less than 0.2V state in grand shorted. After

detecting timer of open state, if the grand shorted (open) state continues 2⁷counts all systems are latched.

To prevent the miss detection there is 4 count interval of mask before starting the timer count.

If PWM=H time is

PWM=H time < 4count・・・Not detect protection because it is in interval time

PWM=H time > 4count・・・Detect protection because it is out of interval time

Please verify enough to operate narrow PWM.

LEDx

Interval of mask

Timer count

CLK

FAIL

1 2 3 4 1 2

Figure 14. Timing chart of timer count

○LED_GND （HTSSOP-B28:21PIN

HSOP-M28：14PIN）

The LED_GND pin is a power ground pin used for the LED driver block.

○UVLO （HTSSOP-B28:25PIN HSOP-M28：18PIN）

This pin is used to for step-up DC/DC converter. When UVLO pin voltage reaches 3.0V (Typ.) or more, IC will initiate

step-up operation. If it reaches 2.7V (Typ.) or less, the IC will stop the step-up operation.

The UVLO pin is of the high impedance type and involves no pull-down resistor, resulting in unstable potential in the

open-circuited state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider or

otherwise.

For calculation examples, refer to information in ’3.1 application explanation/UVLO setting procedure’

○LSP （HTSSOP-B28:26PIN

HSOP-M28：19PIN）

The setting pin for detection voltage of LED short circuit protection. The LED short circuit detection voltage is set to 9V

(Typ.) with the LSP pin being in the open-circuited state. However, making a change to the LSP pin input voltage will allow

the threshold for LED short circuit protection to be changed.

The relation between the LSP pin voltage and the LED short circuit protection detection voltage is given by the following

equation.

VLED_SHORT

VLSP

ꢀ[V ]

SHORT

Here LED_SHORT：LED detection voltage

VLSP：LSP setting voltage

LSP pin input voltage setting should be made in the range of 0.3V to 2.5V.

For setting example, refer to information in’3.1 application explanation/LSP setting procedure’

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○STB (HTSSOP-B28:27PIN

HSOP-M28：20PIN）

The pin is used to ON/OFF the IC and allowed for use to reset the IC from shutdown.

The IC state is switched between ON and OFF state according to voltages input in the STB pin. Avoid using the STB pin

between two states (0.8 to 2.0V).

Input sequence of STB/PWM for startup, please input PWM before STB or at the same timing.

While in shutdown mode, the timer keeps counting until the IC is completely shut down. For details of shutdown operation,

refer to information in’3.1 application explanation/ the setting of REG58 capacity and shutdown procedure'

○VCC （HTSSOP-B28:28PIN

HSOP-M28：21PIN）

IC power supply pin. Input range is 9~35V.

VCC pin voltage reaches 7.5V (Typ.) or more, the IC will initiate operation. If it reaches 7.2V (Typ.) or less, IC will be shut

down.

○REG58 （HTSSOP-B28:1PIN

HSOP-M28：22PIN）

The REG pin is used in the DC/DC converter driver block to output 5.8V voltage. The maximum operating current is

15mA.Using the REG pin at a current higher than 15mA can affect the N pin output pulse, causing the IC to malfunction

and leading to heat generation of the IC itself. To avoid this problem, it is recommended to make load setting to the

minimum level.

In addition, The REG58 pin is also allowed for use as discharge timer for DC/DC output capacitance.

For details, refer to information in ’3.1 application explanation/ the setting of REG58 capacity and shutdown procedure'

○CS （HTSSOP-B28:2PIN

HSOP-M28：23PIN）

The CS pin has the following two functions.

１．DC/DC current mode current feed Back function

Current flowing through the inductor is converted into voltage by the current sensing resistor RCS which connected to CS

pin and this voltage is compared with voltage set with the error amplifier to control the DC/DC output voltage.

2．Inductor current limit function (OCP pin)

The CS pin also incorporates the overcurrent protection (OCP) function. If the CS pin voltage reaches 0.4V (Typ.) or more,

switching operation will be forcedly stopped.

For detailed explanation, Please refer to information in “3.2 Selection of DC/DC Components-OCP setting procedure /

DC/DC component current tolerance selection procedure”.

○N （HTSSOP-B28:3PIN

HSOP-M28：24PIN）

The N pin is used to output power to the external NMOS gate driver for the DC/DC converter in the amplitude range of

approximately 0 to 5.8V.Frequency setting can be adjusted by a resistor connected to the RT pin. For details of frequency

setting, refer to the description of the RT pin.

○DCDC_GND （HTSSOP-B28:4PIN

HSOP-M28：25PIN）

The DCDC_GND pin is a power ground pin for the driver block of the output pin N.

○RT （HTSSOP-B28:5PIN

HSOP-M28：26PIN）

The RT pin is used to connect a DC/DC frequency setting resistor. DC/DC drive frequency is determined by connecting the

RT resistor.

・Relationship between Drive frequency and RT resistance (Ideal)

15000

R_RT

[kΩ]ꢀ

f_SW[kHz]

However, drive frequency setting is limited in the range of 100 kHz to 500kHz.

For calculation, refer to information in ’3.1 application explanation/ DC/DC converter drive frequency setting’

When it reaches under VRT×0.90V(typ), DCDC operation will be stopped in order to prevent from high speed oscillation

when the RT resistance is shorted to GND. And when RT pin returns to normal state, DCDC also returns to operation.

○FB （HTSSOP-B28:6PIN

HSOP-M28：27PIN）

The FB pin is an output of DC/DC current mode error amplifier. FB pin detects the voltages of LED pins (1 to 6) and

controls inductor current so that the pin voltage of the LED located in the row with the highest Vf will come to 0.45V(130mA,

typ.). Therefore, the pin voltages of other LEDs will become higher by Vf variation.

FB Voltage keep internal IC with PWM=Low timing, and it can hold by using copied FB voltage while PWM=Low.（The FB

keep voltage range is 0~4V, 40steps）

For setting example, refer to information in ’3.1 application explanation/ the necessity for holding output voltage and FB

voltage while PWM=Low’

○SS （HTSSOP-B28:7PIN

HSOP-M28：28PIN）

Soft start time and duty for soft start setting pin. The SS pin normally sources 2.0uA (Typ.) of current.

The IC has a built-in soft start start-up circuit independent of PWM light modulation, and thereby raises FB voltage as SS

pin voltage rises independent of the duty cycle range of PWM light modulation. When the SS pin voltage reaches 3.7V

(Typ.), soft start operation will be completed to unmask the LED protection function.

For setting example, refer to information in ’3.1 application explanation/ start-up and SS capacity setting explanation’

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3. Application of BD9470AEFV・BD9470AFM

3.1 BD9470AEFV・BD9470AFM examination for application

●Start-up and SS capacity setting explanation

This section described the start-up sequence of this IC.

①

VOUT

SLOPE

Q D

STB

PWM

COMP

OSC

Css

DRIVER

OSC

SS=FB

Circuit

SLOPE

PWM

LED

OVP

PWM

LED_OK

②

LED_OK

0.3～

0.519V

VOUT

KEEP

OVP

③

④

ILED

⑤

LED_DRIVER

LED_OK

⑦

⑥

Figure 15. Timing chart of start-up

○Description of start-up sequence

①STB=PWM=ON

②System is ON.SS starts to charge.

At this time, a circuit in which SS voltage for slow start is equal to FB voltage regardless of whether the PWM pin is set to

Low or High level.

③Since the FB pin and SS pin reach the lower limit of the internal sawtooth wave, the DC/DC converter operates and

VOUT voltage rising.

Until it reachs a certain voltage even PWM=Low by vlotage maintenance function.

（For detailed OVP maintanence function, please refer to”VOUT(OVP) maintanence function section”.）

⑤Vout voltage continues rising to reach a voltage at which LED current starts flowing.

⑥When the LED current reaches the set amount of current, isolate the FB circuit from the SS circuit. With this, the start-up

operation is completed.（Fast start-up is also diasabled by VOUT maintanence function）

⑦After that, conduct normal operation following the feedback operation sequence with the LED pins.

If the SS pin voltage reaches 3.7V or more, the LED protection function will be activated to forcedly end the SS and

FBequalizing circuit.

○ SS capacity setting method

VSS>4.9V FB=Source Mode

REG58

4.9V

Iss[A]

4.7V＜Vss

⇒FB Output Current

=Source Only

Finished Start Up

SS=FB

Css[F]

Time

Figure 16. SS setting procedure in FB Source mode

Boot system as above described, because of start-up in the state of FB=SS, the start-up time can be imaged of the time to

reach the point from the feedback voltage FB from STB = ON.If you SS> 4.9V, FB output current mode will become Source

mode operation.

If the feedback voltage of FB is the same as VSS and the time can be calculated as below.

C_ss[F]×VFB[V ]

T_ss

[Sec]

2[µA]

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However, if SS is set too short, inductor rush current will occur during start-up.In addition, if SS time is set too long, will

result in the brighter in stages.SS capacity will veries with various factors, such as voltagestep-up ratio, DCDC driver

frequency, LED current and output output condencer, so it is recommended to test and confirm on the actual system.

（SS capacity is often set at about 0.047uF～0.47uF approximately as a reference value）

○Setting example

SS time when the start-up is complete and Css = 0.1uF, Iss = 2uA, Vss = 3.7V will be calculated as follows.

0.1E⁻⁶[F] × 3.7[V]

T_ss

= 0.185 [Sec]

2 E⁻⁶[A]

In addition, when FB output is operated in Sink/Source mode（refer to “FB pin output current setting for detailed

explanation.）, SS voltage can be set to be in the range of 3.9V～4.4V at the SS pin voltage resistor divider.Soft-start time

will be set in that case is as follows.

R1[ohm] + R2 [ohm]

Css [F]×R1[ohm]×R2 [ohm]

A =

B =

A ×Vss[V]







= − ln 1 −

[Sec]











VREG58 [V]

R1[ohm]





+ Iss[A] ÷Css[F]







3.9V<VSS<4.4V

FB=Sin/Source Mode

REG58

4.9V

4.4V

3.9V

Iss[A]

3.9V＜Vss＜4.4V

⇒FB Output Current

=Sink & Source mode

Finished Start Up

SS=FB

Css[F]

Time

Figure 17. SS setting procedure in FB sink/ source mode

○Setting example

When R1=200kohm, R2=470kohm, Css=1.0uF, VREG58=5.8V, Iss=2uA, Vss=3.7V, SS time is set as below

7.12 × 3.7







T_ss= −

ln 1−

= 0.266 [Sec]



7.12





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●The setting of REG58 capacity and shutdown procedure

VOUT discharge function is built-in this IC when IC is shutdowned, the below decribes the operation sequence.

②

STB

④

VOUT

ALL SHUTDOWN

STB

REG50

1uS Pulse

2.4V

ON->OFF

DRIVER

PWM

REG58

REG

2.4V/2.5V

ALL SHUTDOWN

LED

PWM

VOUT

ILED

PWM=L:STOP

LED_DRIVER

③

①

Figure 18.Timing chart of shutdown

○Explanation of shutdown sequence

①Set STB pin to “OFF” will stops DC/DC converter and REG58, but LED driver will remain operation.

（Reset signal is output 1uS extent to reset the latch on the IC at this time.Therefore, undershooting will be generated on

LED current, but 1uS is very short will not affect The brightness.）

②Discharge the REG58 pin voltage from 5.8V to 2.4V with −5uA current.

③The VOUT voltage will be fully discharged with ILED current and the ILED current will no longer flow.

④When REG58pin voltage will reach 2.4V (Typ.) or less to shut down all systems

○REG58 capacitance setting procedure

The shutdown time “T_OFF” can be calaulated by the following equation.

[F]× 3.4 [V]

5 [uA]

REG

ꢀ[Sec]

OFF

The longest VOUT discharge time will be obtained when the PWM duty cycle is set to the minimum VOUT.

Make REG capacitance setting with an adequate margin so that systems will be shut off after VOUT voltage is fully

discharged.

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● VCC series resistance setting procedure

VIN

By inserting a series resistor to VCC will has the following affection.

①Reduce the voltage VCC, and it is possible to suppress the heat generation of IC.

（ICC×VIN is power consumption of IC）

RVCC

ΔV

②Possible to Raise the surge ability to VCC.

VCC

However, if resistance is set too large, it is needed to consider that will

result in VCC become VCC<9V（Minimum operation voltage）.So the

appropriate series resistance setting is needed.

I_IN

ICC

The current influx of IC I_IN as shown on the right is

・Circuit current of IC…ICC

REG58

IREG

・Current to load is connected toREG58…IREG

BLOCK

RREG

・Current which used to drive DCDC FET…IDCDC

There are 3 paths within IC and the ΔV of RVCC can be decided.

VCC voltage generated by the relation as above described at that time

can be represented as below.

IDCDC

I_N

DCDC

DRIVER

VCC[V ] = VIN[V ]−

(

ICC[A]+ IDCDC[A]+ IREG[A] × RVCC[Ω] [ꢀV ] > 9[V ]

)

The Criterion of 9V is the minimum operating limit of the IC.

When a series resistance is considered, please set with a sufficient

margin.

Figure 19. ICC paths diagram

○Setting example

Above equation can be transformed as below.

VIN[V ]− 9[V ]

ICC[A]+ IDCDC[A]+ IREG[A]

RVCC[Ω]

In typical operation, VIN=24V, ICC=5.5mA, RREG=10kΩ, IDCDC=2mA can be assumed and the VCC voltage is

24[V ]− 9[V ]

RVCC[Ω]

=1.86[kΩ]

0.0055[A]+ 0.002[A]+ 5.8[V ] 10000[Ω]

However, the result is in typical operation and the variability and margin is not considered.

If the variability of VIN=24V×(-20%）,ICC=8.5ｍA,RREG=10k×(-5%）,REG58=5.8V×(+5%),IDCDC=2mA×(+100%),VCC

operation limit voltage9V×(+20%) are assumed:

24×0.8[V ]− 9×1.2[V ]

0.0085[A]+ 0.002× 2[A]+ 5.8×1.015[V ] (10000[Ω]×0.95)

RVCC[Ω]

= 640[Ω]

According to above result, set RVCC = 640Ω or less is adequate on actual application.

When a series resistance is considered, please set with a sufficient margin.

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●The necessity for holding output voltage and FB voltage while PWM=Low

In conventional control method, DCDC will be stopped and FB voltage become high impendence while PWM=Low.

However, if PWM=0% is continued to inputted to system, output voltage and FB voltage is reduced because of discharge

phenomenon.eventually output voltage is equal to VIN, and FB voltage drop to 0V.There are several problems such as the

following listed if PWM dimming signal is tried to light-up a system.

①Slow start cannot be controlled resulting in the FB voltage overshoot and rush current flow to Inductor.

②Flash phenomenon occur due to start-up control does not work.

③Because there is a need to re-boost, take a long time to light up.

In this IC, the problems as above mentioned is resolved by coping output voltage and FB voltage to IC internally at a time

of PWM from High to Low.

The below describes FB and VOUT voltage holding function in detail.

○Explanation of FB voltage holding function while PWM=Low

PWM signal

LED1

LED2

GMAMP

100pF～2200pF

FB IN

FB COPY

Holding FB Vol.

BLOCK

Figure 20. Block diagram of KEEP_FB

FB holding function means FB voltage will be copy to IC internally at a time of PWM from High to Low, FB voltage will be

maintained even in the period of PWM=Low.

Because FB voltage resolution is split by 40 from 4V, so the voltage can be copied to IC internally in 0.1V Step.

In addition, FB pin voltage will be influenced by DCDC operation, the copied have ±0.1V difference problem. But because

FB voltage is returned as feedback voltage immediately and will not cause an operational problem while PWM=H, it is

recommended to add about 100pF～2200pF to FB pin for noise reduction.

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②

③

④ ⑤

①

PWM

FB COPY

Figure 21. Timing chart of KEEP_FB

①PWM=High, normal feedback operation by LED pin

②FB voltage is copied to IC at a time of PWM from High to Low. FB voltage will be copied by less than 1Bit.

For Example：when FB=2.16V, FB COPY voltage is 2.1V.

③GMAMP is works as Buffer with while PWM=Low, FB voltage is discharged to FB COPY voltage.

④FB COPY=FB voltage.

⑤FB COPY=FB voltage and maintain.

If PWM=0% and because follow the state⑤ continuously, FB voltage will not dropped by natural discharge.

※Notice

FB voltage holding function is performed at 0.1V STEP. If PWM signal is in low duty, FB voltage is not able to rise

sufficiently when FB series resistance is small causing to RFB×IFB(typ.100uA)＜0.1V(typ.), The output voltage may not be

boosted up to the set voltage.

Therefore, it is recommended to set RFB> 2kohm so that ΔV = RFB × IFB> 0.2V.

IFB(100uA typ)

RFB

CFB

⊿V=RFB×IFB>0.2V

Figure 22. Voltage to FB resistor

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●Explanation of VOUT（OVP） voltage holding function when PWM=Low

VIN

VOUT

VCC

OVP

OVP_IN

OVP COPY

LED_OK

Holding OVP

Vol. BLOCK

PWM signal

H : DCDC ON

L : DCDC OFF

OVP

COMP

CONTROL

LOGIC

DRIVER

ICOMP

SLOPE

DCDC_GND

LED1-6

Figure 23. Block diagram of KEEP_OVP

OVP holding function means VOUT(OVP) voltage will be copy to IC internally at a time of PWM from High to Low, voltage

will be maintained even in the period of PWM=Low.

In addition to measures of the above problems, by applying this function, the high-speed start-up can be achieved without

depending on the PWM.

Because VOUT voltage resolution is the same as FB holding function which is split by 40 from 4V,so the voltage can be

copied to IC internally in 0.1V Step.

The description of OVP holding function is divided into narrow PWM operation and start-up operation.

○Explanation of OVP holding function at start-up

PWM

②

①

⑤

OVP

OVP COPY

③

④

Figure 24. Timing chart 1 of KEEP_OVP

In order to launch high speed start-up without depending on the PWM DUTY, OVP holding function will behave like the

following descriptions.

①PWM=High, normal boost operation.

②OVP voltage is copied into IC when PWM is from High to Low.OVP voltage will be copied upper 1BIT at this time. For

example: if OVP=2.43V, the copied voltage is 2.5V in IC.

③The copied OVP voltage will be compared with OVP pin voltage internally, if OVP_COPY>OVP, DCDC is operated.In

other words, it is possible to achieve fast start-up by letting the voltage on the 1BIT boosted up in the interval of PWM =

Low.

④When OVP_COPY<OVP pin voltage, DCDC is stopped.

⑤Even if in the period of PWM=Low and VOUT is discharged, output voltage will be hold by performing DCDC operation

in order to let OVP_COPY＜OVP pin voltage.

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○Explanation of OVP holding function in narrow PWM duty

PWM

①

②

③

④

OVP

OVP COPY

Figure 25. Timing chart 2 of KEEP_OVP

DCDC operates only in the duration of PWM=High while narrow PWM is inputted, output voltage drops when PWM=0%.

But, DCDC is operated by coping voltage even if PWM=Low duration in this IC and output voltage will not drops.

①PWM=High, normal operation.

②OVP voltage is copied into IC when PWM is from High to Low.OVP voltage will be copied under 1BIT at this time. For

example: if OVP=2.43V, the copied voltage is 2.4V in IC.

③VOUT is discharged by OVP resistance.

④When copied OVP_COPY＞OVP pin voltage, DCDC is operated, when OVP_COPY＜OVP voltage, DCDC is stops.

When operates in PWM=0%, the point④ will be repeated and repeated, so the output voltage will not drops naturally.

○Condition of copy OVP voltage

The copied OVP pin voltage as above explanation, it has upper and lower 1BIT difference according to below condition.

Conditions of copy upper 1BIT

：From startup to completion of step-up

：OVP detection state

Conditions of copy lower 1BIT

：Normal operation state ( OVP undetected state)

※The reason about why copy the voltage of upper 1BIT when OVP is detected

When OVP is detected by OVP=3V and stops DCDC operation. After that while PWM=Low and if copy lower 1BIT voltage will results in

OVP=2.9V and release OVP detection function, therefore it is designed to copy upper 1BIT when OVP is detected.

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●FB current Source mode・Sink/Source mode

The output of GMAMP is constant current control in normal operation ans output anout±100uA(typ.) in this IC.

But, when PWM scanning operation and local dimming is performed, total LED current and output voltage will different by

each timming and FB feedback voltage.The below describes the this operation.

PWM

1,2,3

PWM

④

CFB

4,5,6

⑥

RCS

RFB

②

③

PGND

OVP

PWM1

PWM2

PWM3

①

LED1

LED2

LED3

LED4

LED5

LED6

PWM4

PWM5

PWM6

ILED

⑤

VOUT

Figure 26. Timing chart of FB sink/source mode

As above shown,short PWM1,2,3 ans PWM4,5,6, assumed that scanning operation is performed.

At this time, the sequence is described as below.

①When PWM4,5,6=High→Low, FB voltage, VOUT（OVP）voltage is copied

②Copied voltage is hold.

③When PWM1,2,3=High again, normal DCDC operation

④When PWM4,5,6=High again, LED current increase.

⑤Because LED current increase resulting in FB voltage change.it take a long transition time because FB source current is

100uA at this time, therefore FB voltage is not insufficient and output voltage and LED current will drop.

⑥FB voltage reaches the feedback voltage and LED current and output voltage will operate normally.

In other words, ILED current drops at the point ⑤, This may be due to the transition time of the behavior that FB current

sink first and then charge again.

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Therefore, in order to solve this problem in this IC, equipped with a mode of “FB current only source 0uA～+100uA”as a

countermeasure to reduce the LED current drop problem.

“FB Source mode”is described as below.

PWM

1,2,3

PWM

④

4,5,6

⑥

⑦

②

③

①

ILED

⑤

VOUT

Figure 27. Timing chart of FB source mode

①when PWM4,5,6=High→Low, FB voltage, VOUT（OVP）voltage is copied

②copied voltage is hold.

③when PWM1,2,3=High again, normal DCDC operation.but, FB voltage is larger than feedback voltage, and VOUT setting

voltage also higher.

③when PWM4,5,6=High, LED current increases.

④although LED current is increased but the FB voltage has reached the feedback voltage and will not change at this

time.Therefore, there is no transition and VOUT, LED current will not drop.

⑥LED current and output voltage is operate normally

⑦When PWM1,2,3=Low, LED current reduces.But, FB is only has source ability , FB voltage is maintained continuely

（But, despite the decreasing of LED current, output voltage is increases because FB voltage is not changed.）

According to above operation, the LED undershoot problem cab be prevented by FB source mode.

However, the above description is a simplified explanation for behavior, because the actual behavior of a waveform is

different from the above, please check on the actual system.

When FB source mode is used, care must be taken to the following contents.

Because it can be held at a higher voltage than normal FB voltage, output voltage may be higher. Therefore, please note

that the heat might be higher than PWM = 100% while scanning operation is performed.

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●LED Current setting

Setting of LED output current “ILED” can be made by connecting a resistor RISET to the ISET pin.

RISET and ILED current setting equation

3000

R_ISET

[kΩ]ꢀꢀ

I_LED[mA]

However, LED current setting should be made in the range of 40mA to 150mA.

And the setting of ISET resistor is bellow at using 150mA to 250mA.

R_ISET= 2653× ( I_LED[mA] )^−0.9753[kΩ]ꢀꢀ

ILED(mA)

150

160

170

180

190

200

210

220

230

240

250

RSET(kohm)

20.00 18.80 17.72 16.76 15.90 15.12 14.42 13.78 13.19 12.66 12.16

○Setting Example

To set ILED current to 100mA, RISET resistance is given by the following equation

3000

R_ISET

= 30 [kΩ]ꢀꢀ

I_LED[mA] 100[mA]

●DC/DC converter drive frequency setting

DC/DC converter drive frequency is determined by making RT resistance setting.

○Drive frequency vs. RT resistance (ideal) equation

15000

R_RT

[kΩ]ꢀ

f_SW[kHz]

Here fsw = DC/DC converter oscillation frequency

[kHz]

This equation has become an ideal equation without any correction item included.

For accurate frequency settings, thorough verification should be performed on

practical sets.

○Setting example

To set DC/DC drive frequency “fsw” to 200 kHz, RRT is given by the following equation

15000

R_RT

= 75 [kΩ]ꢀꢀ

f_sw[kHz] 200[kHz]

And , the drive frequency setting range is 100kHz～500kHz.

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●UVLO setting procedure

UVLO pin for step-up DC/DC power supply. If the UVLO pin voltage reaches 3.0V (Typ.) or more, the IC will start step-up

operation. If it reaches 2.7V (Typ.) or less, the IC will stop the step-up operation.

UVLO pin is the high impedance type and no pull-down resistor inside, resulting in unstable potential in the open-circuit

state. To avoid this problem, be sure to set input voltage with the use of a resistive divider.

While the VIN voltage to be detected is set by the use of resistive dividers R1 and R2 as described below, resistance

setting will be made by the following equation.

○UVLO setting procedure

Assume that VIN is reduced and detected,

UVLO is “VIN_DET”, R1 and R2 setting will be made by the following equation:

(VIN_DET[V ]− 2.7[V ])

R1= R2[kΩ]×

[kΩ]ꢀ

2.7[V

]

○UVLO release voltage setting equation

When R1 and R2 setting is determined by the equation shown above,

UVLO release voltage will be given by the following equation.

(R1[kΩ]+ R2[kΩ])

VIN_CAN= 3.0V ×

[V ]ꢀ

R2[kΩ]

VIN

UVLO

ON/OFF

2.7V/3.0V

CUVLO

Figure 28. Block diagram of UVLO

○Setting example

Assuming that the normal VIN operating voltage is 24V, UVLO detection voltage is 18V, and R2 resistance is 30kΩ, R1

resistance setting is made by the following equation

(VIN_DET[V ]− 2.7[V ])

2.7[V ]

(18[V ]− 2.7[V ])

2.7[V ]

R1= R2[kΩ]×

= 30[kΩ]×

=170 [kΩ]

And, when UVLO release voltage VIN_CANsetting is made with R1 and R2, it will be given by the following equation

(R1[kΩ]+ R2[kΩ])

R2[kΩ]

30[kΩ]+170[kΩ]

30[kΩ]

VIN_CAN= 3.0[V ]×

= 3.0[V ]×

[V ]ꢀ= 20 [V ]

To select DC/DC components, give consideration to IC variations as well as individual component variations, and then

conduct thorough verification on actual systems.

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●OVP/SCP setting method

The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage.

The OVP pin is a high impedance type and no pull-down resistor inside, resulting in unstable potential in the open circuit

state. To avoid this problem, be sure to make input voltage setting with the use of a resistive divider.

Conditions for each OVP protections are as listed in the table below.

Protection

Detection

Condition

Release

Condition

Timer

Operation

Protection name

Protection type

All latch

FAIL pin

GND

OVP Timer SET /

OVP Cancel

OVP Detect /

DCDC STOP

SCP

OVP

OVP>2.9V OVP<2.9V

Yes

Only DCDC converter

stops during detection

All latch

OVP

OVP>3.0V OVP<3.0V

OVP<0.1V OVP>0.1V

OPEN

GND

Yes

The following describes the setting procedures of that VOUT pin voltage to be detected is set by the use of resistive

dividers R1 and R2 as shown in the circuit diagram below.

○OVP detection setting method

VOUT

Assuming that a voltage causing VOUT to abnormally rise

and detecting OVP is “VOVP_DET”

R1 and R2 setting will be made by the following equation.

(VOVP_DET[V ]−3.0[V ])

OVP

R1= R2[kΩ]×

[kΩ]ꢀ

3.0[V ]

○Timer set・OVP release setting equation

DCDC_STOP_COMP

When R1 and R2 setting is determined by the equation

shown above, OVP release voltage VOVP_CANwill be

given by the following equation:

3.0V

H:STOP

L:ACT

OVP_TIMER_COMP

(R1[kΩ]+ R2[kΩ])

DRIVER

VOVP = 2.9V ×

[V ]ꢀ

CAN

R2[kΩ]

2.9V

○SCP detection equation

SCP_TIMER_COMP

When R1 and R2 setting is determined by the equation

shown above, SCP setting voltage VSCP_DETwill be given

by the following equation.

0.1V

(R1[kΩ]+ R2[kΩ])

VSCP_DET= 0.1V ×

[V ]ꢀ

Timer

65536

Timer

65536×8

R2[kΩ]

Figure 29. OVP block diagram

○Setting example

Assuming that normal VOUT voltage is 40V, OVP detection voltage VOVP_DETis 48V, and R2 resistance is 10kΩ, R1

resistance is calculated by the following equation

(VOVP_DET[V ]− 3.0[V ])

3.0[V ]

(48[V ]− 3[V ])

3[V ]

R1 = R2[kΩ]×

=10[kΩ]×

=150 [kΩ]

When OVP release voltage VOVP_CANsetting is made with the said R1 and R2, it will be given by the following equation

(R1[kΩ]+ R2[kΩ])

R2[kΩ]

10[kΩ]+150[kΩ]

10[kΩ]

VOVP = 2.9[V ]×

= 2.9[V ]×

[V ]ꢀ= 46.4 [V ]

CAN

SCP detection voltage is given by the following equation

(R1[kΩ]+ R2[kΩ])

VSCP_DET= 0.1[V ]×

10[kΩ]+150[kΩ]

10[kΩ]

= 0.1[V ]×

[V ]ꢀ=1.6 [V ]

R2[kΩ]

Give consideration to IC variations as well as individual component variations, and then evaluate on actual systems.

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●LSP setting procedure

LED SHORT threshold voltage can be adjusted by setting LSP pin voltage.

LED SHORT detection voltage is set to 9V when LSP pin=OPEN state.

Please set input voltage of LSP pin from 0.3V~2.5V range.

The relation between LSP pins and LED SHORT protection voltage as below.

VLED_SHORT

VLSP

ꢀ[V ]

SHORT

Also, LSP pin divides 4V within the IC using resistive dividers (see the circuit diagram shown below)

Therefore, connecting an external resistor to the LSP pin will produce resistance combined with the internal IC resistance.

Consequently, LSP pin voltage setting using external resistive dividers, it is recommended to connect them having

resistance little affected by the internal resistance.(Smaller resistance have less influence on internal resistance, but will

result in larger power consumption.)

REG58=5.8V

REF=4V

R3=

3100kΩ

LSP

900kΩ

CLSP

900kΩ

LEDx

100kΩ

Figure 30. LSP Block diagram

○LSP detection voltage setting

If the setting of LSP detection voltage VLSP is made by dividing the REG58V voltage by the use of resistive dividers

R1and R2, VLSP will be given by the following equation.





R2[kΩ]

(R1[kΩ]+ R2[kΩ]





VLSP = REG58[V ]×

×10 [V ]ꢀ(1)







However, this equation includes no internal IC resistance. If internal resistance is taken into account, detection voltage

VLSP will be given by the following equation.





R2[kΩ]× R4[kΩ]×

(

REG58[V ]× R3+ REF[V ]× R1[kΩ]

)





VLSP =

×10 [V ]ꢀ(2)

(R1[kΩ]× R3[kΩ]× R2 + R4

(

)

+ R2[kΩ]× R4[kΩ]× R1[kΩ]+ R3[kΩ]

(

)





Make setting of R1 and R2 resistance so that a difference between resistance values found by Equations (1) and (2) will

come to approximately 2% or less as a guide.

○Setting example

Assuming that LSP is approximated by Equation (1) in order to set LSP detection voltage to 5V, R1 comes to 53kΩ andR2

comes to 5kΩ.LSP detection voltage taking into account internal IC resistance by Equation (2), it will be given as





5[kΩ]× 900[kΩ]×

(

5.8[V ]× 3100[kΩ] + 4[V ]× 53[kΩ]

)





VLSP =

×10 = 5.033V[V ]

(53[kΩ]×3100[kΩ]× 5[kΩ] + 900[kΩ]

(

)

+ 5[kΩ]×900[kΩ]× 53[kΩ] + 3100[kΩ]

(

)





The difference is given as:

(

5.033[V ]−5[V ] /5[V ]×100 = 0.66%

)

As a result, this setting will be little affected by internal impedance.

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●Timer latch function

This IC has a built-in timer latch counter to make setting of timer latch time by counting a clock frequency set with the RT

pin.

○Timer latch time

The timer latch counter begins counting from the timing when any abnormal state is detected. The timer will be latched

after a lapse of a period of time given by the following equation.

If the abnormal state continues even when PWM is set to Low level, the counter will not reset counting.

R_RT

1.5×10¹⁰

R_RT[kΩ]

1.5×10⁷

LATCH_TIME= 2¹⁶×

= 65536×

[S]ꢀ

Here LATCH_TIME= A period of time, which the timer is latched

R_RT=RT pin connecting resistance

Protection time which described above is applied for LED pin OPEN protection, LED pin SHORT protection, SCP

protection.

The protection of FB overshoot and OVP protection as below:

R [kΩ]

1.5×10

LATCH = 2 ×

= 262144×

[S]ꢀ

TIME

1.5×10

Clock oscillation of timer latch uses DCDC clock. So timer latch time depend on unevenness of DCDC oscillation. In

150kHz, timer latch time is ±5% unevenness.

○Setting Example

In LED_OPEN protection, LED_SHORT protection, SCP protection,

When RT resistance=100kohm, the timer latch time is

R_RT[kΩ]

1.5×10⁷

100[kΩ]

1.5×10⁷

LATCH_TIME= 65536×

= 65536×

= 0.437[S]ꢀ

And, FB overshoot protection, OVP protection is

R [kΩ]

1.5×10

100[kΩ]

1.5×10

LATCH = 524288×

= 262144×

= 1.75[S]ꢀ

TIME

LED1 SHORT Pro.

detect

12V

0.8V

LED1_Voltage

Oscllator

(internal IC)

CP COUNTER

CP COUNT UP

END

CP COUNT UP

START

I_LED1

Current

LED1

LATCH UP

FAIL

(OPEN)

LOW

FAIL

DET

Figure 31. Timing chart of LSP time latch

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3.2 Selection of DCDC components

●OCP setting procedure/DCDC component current tolerance selection procedure

The OCP detection function that is one of the functions of the CS pin will stop the DC/DC converter operating if the CS pin

voltage becomes greater than 0.4V. Consequently, it is needed to calculate a peak current flowing through the coilL and

then review the resistance of RCS. Furthermore, a current tolerance for DC/DC components should be larger than that for

peak current flowing through the coil L.

The following section describes the peak coil current calculation procedure, CS pin connection resistor RCS selection

procedure, and DC/DC component current tolerance selection procedure

○Calculation of coil current Ipeak

Ripple voltage generated at the CS pin is determined by conditions for DC/DC application components. Assuming the

conditions:

VOUT

output voltage=VOUT [V]

LED total current=IOUT [A]

VIN

DCDC input voltage=VIN [V]

DCDC efficiency=η [%]

mean input current IIN required for the whole system is given by the following

equation

fsw

V_OUT[V ]× I_OUT[A]

V_IN[V ]×η[%]

I_IN

[A]ꢀ

Rcs

Further, according to drive operation with the DC/DC converter switching

frequency fsw [Hz], inductor ripple current ΔIL [A] generated at the inductor L

is given by the following equation.

DCDC_GND

(V_OUT[V ]−V_IN[V ])×V_IN[V ]

L[H]×V_OUT[V ]× f_SW[Hz]

ΔIL =

[A]

As a result, the peak current Ipeak of IL is given by the following equation.

∆IL[A]

Ipeak = I_IN[A]+

[A](1)

(V)

○CS pin connection resistor RCS selection procedure

The current Ipeak flows into RCS to generate voltage.(See timing chart

shown to the right.)

The voltage VCSpeak is given by the following equation.

（A)

(t)

VCS_peak= Rcs× Ipeak [V ]

Ipeak

Imin

If this VCSpeak voltage reaches 0.4V, DC/DC output will stop.

Consequently, to select RCS resistance, the following condition should be

met.

ΔIL

IIN

(t)

Rcs[Ω]× Ipeak[A] < 0.4[V ]

（V)

0.5V

○DCDC component current tolerance selection procedure

VCSpeak

Iocp current needed for OCP detection voltage CS to reach 0.4V is given

^{by the following equation}0.4[V ]

I_ocp

[A](2)

(t)

Rcs[Ω]

Figure32.

DCDCapplication diagram and coil current

The relation among Ipeak current (Equation (1)), Iocp current (Equation (2)),

I _peak< I_ocp

Max. current tolerance for component

DC/DC application components including FETs, inductors, and diodes should be selected so that the Equation shown

above will be met.

Furthermore, it is recommended to normally use DC/DC application components in continuous mode. Assuming that the

lower limit value of coil ripple current is Imin, the following equation should be met

∆IL[A]

Imin = I_IN[A] −

[A] > 0ꢀ

A failure to meet this condition is referred to as discontinuous mode.

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○Setting example

Output voltage=VOUT [V]=40V

LED total current=IOUT [A]=120mA×6ch=0.72A

DCDC input voltage=VIN [V]=24V

DCDC efficiency=η[%]=90%

mean input current IIN required for the whole system is given by the following equation

_OUT[V ]× I_OUT[A]

V_IN[V ]×η[%]

40[V ]×0.72[A]

24[V ]×90[%]

I_IN[A] =

ꢀ=

=1.33 [A]

DCDC switching frequency=fsw[Hz]=200kHz

Inductor L[H]=47μH

The Inductor ripple currentΔIL[A] is:

(V_OUT[V ]−V_IN[V ])×V_IN[V ]

L[H]×V_OUT[V ]× f_SW[Hz]

(40[V]− 24[V ])×24[V ]

ΔIL =

ꢀ=

=1.02 [A]

47×10⁻⁶[H]×40[V ]×200×10³[Hz]

As a result, the IL peak current Ipeak is:

∆IL[A]

1.02[A]

… Result of peak current

=1.84 [A]

calculation

Ipeak = I_IN[A]+

[ꢀA] =1.33[A]+

When RCS resistance is set to 0.15ohm, the VCS peak voltage will be given by the following equation

… Result of review of

VCS_peak= Rcs× Ipeak = 0.15[Ω]×1.84[A] = 0.276[V ] < 0.5V

RCS resistance

Consequently, the result meets the condition.

Furthermore, I_OCPcurrent at which OCP is detected is given by the following equation

0.4[V ]

I_ocp

= 2.67 [A]

0.15[Ω]

If the current tolerance for components to be used (e.g. FETs, inductors, diodes) is smaller than 2.5A,

… Result of review of current

tolerance for DC/DC components

Max. Current tolerance for component

I _peak< I_OCP

=1.84[A] < 2.67[A] < 3.0[A]

As a result, since the condition above is met, the selection of components is accepted.

And, the lower limit of IL ripple current Imin is:

∆IL[A]

1.02[A]

Imin = I_IN[A]−

[A] =1.33[A]−

= 0.82[A] > 0ꢀ

The system will not be put into discontinuous mode.

To select DC/DC components, please consider IC variations as well as individual component variations, andthen conduct

thorough verification on practical systems.

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●Selection of Inductor

The value of inductor has significant influence on the input ripple current. As shown by Equation (1), the larger the inductor

and the higher the switching frequency, the inductor ripple current ∆IL becomes

increasingly

lower.

(V_OUT−V_IN) ×V_IN

L ×V_OUT× f_SW

ΔIL =

[ꢀA]ꢀꢀꢀꢀ・・・・・ꢀꢀ(1)

Efficiency as shown by Equation (2), peak input current is given as Equation

(3).

ΔI

V_OUT× I_OUT

V_IN× I_IN

η =

ꢀꢀꢀꢀꢀ・・・・・ꢀꢀ(2)

V_IN

ΔIL V_OUT× I_OUT

ΔIL

IL_MAX= I_IN

ꢀꢀ+ ꢀꢀ ꢀ・・・・・ꢀꢀ(3)

V_IN×η

I_L

Here,

L：Reactance value [H]

V_IN：input voltage[V]

I_IN：input current[A]

_OUT：DC/DC output voltage[V]

V_OUT

_OUT：output current(LED total current)[A]

_SW：oscillation frequency[Hz]

If a current in excess of the rated current of the inductor applies to the

coil, the inductor will cause magnetic saturation, resulting in lower

efficiency.

Select an inductor with an adequate margin so that peak current will

not exceed the rated current of the inductor.

R_CS

C_OUT

To reduce power dissipation from and increase efficiency of induct

or, select an inductor with low resistance component (DCR or AC

R).

Figure33.

DCDC application circuit and coil current

●Selection of switching MOSFET transistors

There will be no problem for switching MOSFET transistors having absolute maximum rating higher than rated current of

the inductor L and VF higher than “C_OUTbreakdown voltage + Rectifier diode”. However, to achieve high-speed switching,

select transistors with small gate capacity (injected charge amount).

・Rated current larger than current protection setting current is recommended

・Selecting transistors with low On resistance can obtain high efficiency.

●Selection of rectifier diodes

Select current capability higher than the rated current of the inductor L and inverse breakdown voltage higher that C_OUT

break-down voltage, particularly having low forward voltage VF.

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3.3 Timing Chart

7.5V

VCC

2.0V

0.8V

STB

2.4V

REG58

2.6V

FAIL

GND

( normal state )

1.5V

ISET

3.7V

LED

feed-back

SS=FB or LED

feed-back

VOUT

PWMｘ

ILEDｘ

1.5V

0.8V

LED_OPEN

Disaable

Enable

Disaable

LED_SHORT

Disaable

Enable

Disaable

LED_GND_SHORT

ISET_GND_SHORT

RT_GND_SHORT

Disaable

UVLO

REG58_UVLO

VCC_UVLO

Disaable

OVP

SCP

Figure 34. Timing Chart

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3.4 List of Protection Functions

●List of protection detecting condition

Detection

Detection condition

PWM

Protection

names

Release

condition

Protection

type

Timer

Detection pin

condition

Latch

(Only detected

ｃｈ)

Latch

(Only

detected ｃｈ)

LED OPEN

LEDｘ

LEDx < 0.20V

SS>3.7V

LEDx > 0.20V

2 ¹⁶count

LEDx > 9V

LEDx < 9V

LEDSHORT

LEDｘ

SS>3.7V

(LSP=OPEN)

LED GND

SHORT

ISET GND

SHORT

RT GND

SHORT

2 ¹⁶+ 2⁷

count

Immediately

detect

Immediately

detect

Immediately

detect

Immediately

detect

Immediately

detect

LEDｘ

ISET

LEDx < 0.20V

Under ISET×90%

Under RT×90%

UVLO<2.7V

REG58<2.4V

VCC<7.2V

LEDx > 0.20V

Latch

Auto-restart

Latch

Canceled

ISET=GND State

Canceled

RT=GND State

UVLO

REG58 UVLO

VCC UVLO

OVP

UVLO

REG58

VCC

OVP

UVLO>3V

REG58>2.6V

VCC>7.5V

OVP<2.9V

OVP>0.1V

OVP>3.0V

2 ¹⁸count

SCP

OVP<0.1V

2 ¹⁶count

Latch

Immediately

detect

OCP

OCP>0.4V

Pulse-by-Pulse

* To clear the latch type, STB should be set to “L” once, and then to “H”

* The count of Timer means ” 1count = 1 duty of switching frequency.

●List of protection detecting operation

Operation when the hysteresis type protection is detected

Protection Functions

DC/DC

LED Driver

Soft start

FAIL pin

Only detected LED stops

operating after CP counting

Only detected LED stops

operating after CP counting

Open after CP

counting

Open after CP

counting

Open after CP

counting

LED OPEN

LEDSHORT

LED GNDSHORT

ISET GND SHORT

RT GND SHORT

STB

Continues operation

Not discharged

Continues operation

Not discharged

Discharge

Stops operating after

CP counting

Instantaneously stops

operating

Instantaneously stops

operating

Instantaneously stops

operating

Instantaneously stops

operating

Instantaneously stops

operating

Instantaneously stops

operating

Stops operating after

CP counting

Stops operating after CP counting

Instantaneously stops operating

Normal Operation

OPEN

immediately

Not discharged

Discharge

LOW

OPEN

immediately

OPEN

immediately

OPEN

immediately

Stops (and REG58<2.4V)

UVLO

Instantaneously stops operating

Stops operating after CP counting

Discharge

REG58 UVLO

VCC UVLO

OVP

Discharge

OPEN

Discharge

immediately

Open after CP

counting

Discharge

Stops operating after

CP counting

Open after CP

counting

SCP

OCP

Stops operating after CP counting

Continues operation

Discharge

limits duty cycle

Not discharged

LOW

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BD9470AFM・BD9470AEFV

4. Caution on use

1.) We pay utmost attention to the quality control of this product. However, if it exceeds the absolute maximum ratin

gs including applied voltage and operating temperature range, it may lead to its deterioration or breakdown. Furth

er, this makes it impossible to assume a breakdown state such as short or open circuit mode. If any special mod

e to exceed the absolute maximum ratings is assumed, consider adding physical safety measures such as fuses.

2.) Making a reverse connection of the power supply connector can cause the IC to break down. To protect the IC f

orm breakdown due to reverse connection, take preventive measures such as inserting a diode between the exter

nal power supply and the power supply pin of the IC.

3.) Since current regenerated by back electromotive force flows back, take preventive measures such as inserting a c

apacitor between the power supply and the ground as a path of the regenerative current and fully ensure that ca

pacitance presents no problems with characteristics such as lack of capacitance of electrolytic capacitors causes a

t low temperatures, and then determine the power supply line. Provide thermal design having an adequate margin

in consideration of power dissipation (Pd) in the practical operating conditions.

4.) The potential of the GND pin should be maintained at the minimum level in any operating state.

5.) Provide thermal design having an adequate margin in consideration of power dissipation (Pd) in the practical oper

ating conditions.

To mount the IC on a printed circuit board, pay utmost attention to the direction and displacement of the IC. Furthermore,

the IC may get damaged if it is mounted in an erroneous manner or if a short circuit is established due to foreign matters

entered between output pins or between output pin and power supply GND pin.

6.) Note that using this IC in strong magnetic field may cause it to malfunction.

7.) Please set the output Tr not to over absolute Maximum Ratings and ASO. CMOS IC and plural power supply IC

have a possible to flow lush current momentarily. Please note VCC capacitor, VCC and GND layout.

8.) This IC has a built-in thermal-protection circuit (TSD circuit).

The thermal-protection circuit (TSD circuit) is a circuit absolutely intended to protect the IC from thermal runaway,

not intended to protect or guarantee the IC. Consequently, do not use the IC based on the activation of this TS

D circuit for subsequent continuous use and operation of the IC.

9.) When testing the IC on a set board with a capacitor connected to the pin, the IC can be subjected to stress. In

this case, be sure to discharge the capacitor for each process. In addition, to connect the IC to a jig up to the t

esting process, be sure to turn OFF the power supply prior to connection, and disconnect the jig only after turnin

g OFF the power supply.

10.) This monolithic IC contains P + Isolation and P substrate layers between adjacent elements in order to keep them

isolated.

P-N junctions are formed at the intersections of these P layers and the N layers of other elements, thus making up

different types of parasitic elements.

For example, if a resistor and a transistor is connected with pins respectively as shown in Fig.

When GND>(Pin A) for the resistor, or when GND>(Pin B) for the transistor (NPN), P-N junctions operate as a a

parasitic diode.

When GND>(Pin B) for the transistor (NPN), the parasitic NPN transistor operates by the N layer of other element

adjacent to the parasitic diode aforementioned.

Due to the structure of the IC, parasitic elements are inevitably formed depending on the relationships of potential. The

operation of parasitic diodes can result in interferences in circuit operation, leading to malfunctions and eventually

breakdown of the IC. Consequently, pay utmost attention not to use the IC for any applications by which the parasitic

elements are operated, such as applying a voltage lower than that of GND (P substrate) to the input pin.

Transistor (NPN)

Resistor

(Pin A)

(Pin B)

GND

P substrate

GND

Parasitic element

GND

Parasitic element

(Pin B)

(Pin A)

Parasitic element

ＧＮＤ

Adjacent other elements

GND

Parasitic

Figure 35. Example of Simple Structure of

Monolithic IC

Status of this document

The Japanese version of this document is formal specification. A customer may use this translation version only for a

reference to help reading the formal version.

If there are any differences in translation version of this document formal version takes priority

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BD9470AFM・BD9470AEFV

●Ordering Information

B D 9

0 A F M

E 2

Part Number

Package

FM: HSOP-M

Packaging and forming specification

E2: Embossed tape and reel

B D 9

0 A E

E 2

Part Number

Package

EFV: HTSSOP-B

Packaging and forming specification

E2: Embossed tape and reel

●Physical Dimension Tape and Reel Information

www.rohm.com

TSZ22111・15・001

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BD9470AFM・BD9470AEFV

6. Revision history

Date

Revision

Changes

New Release

26.Oct.2012

09.Jan.2013

001

002

P6 / Verified minimum ISET resistor

P10 / Verified ISET terminal instruction

P23 / Verified LED Current setting

P2 / Change Pin Configuration

P1 / Delete PbFree, RoHS

ADD NOTICE

002

19.Oct.2013

003

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19.Oct.2013 Rev.003

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TSZ22111・15・001

Daattaasshheeeett

Notice

Precaution on using ROHM Products

1. Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,

OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you

intend to use our Products in devices requiring extremely high reliability (such as medical equipment ^{(Note 1)}, transport

equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car

accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or

serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.

Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any

damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific

Applications.

(Note1) Medical Equipment Classification of the Specific Applications

JAPAN

USA

CHINA

CLASSⅢ

CLASSⅣ

CLASSⅡb

CLASSⅢ

2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor

products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate

safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which

a failure or malfunction of our Products may cause. The following are examples of safety measures:

[a] Installation of protection circuits or other protective devices to improve system safety

[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure

3. Our Products are designed and manufactured for use under standard conditions and not under any special or

extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way

responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any

special or extraordinary environments or conditions. If you intend to use our Products under any special or

extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of

product performance, reliability, etc, prior to use, must be necessary:

[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents

[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust

[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,

H2S, NH3, SO2, and NO2

[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves

[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items

[f] Sealing or coating our Products with resin or other coating materials

[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of

flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning

residue after soldering

[h] Use of the Products in places subject to dew condensation

4. The Products are not subject to radiation-proof design.

5. Please verify and confirm characteristics of the final or mounted products in using the Products.

6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,

confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power

exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect

product performance and reliability.

7. De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual

ambient temperature.

8. Confirm that operation temperature is within the specified range described in the product specification.

9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in

this document.

Precaution for Mounting / Circuit board design

1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product

performance and reliability.

2. In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the

ROHM representative in advance.

For details, please refer to ROHM Mounting specification

Notice - GE

Rev.002

Daattaasshheeeett

Precautions Regarding Application Examples and External Circuits

1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the

characteristics of the Products and external components, including transient characteristics, as well as static

characteristics.

2. You agree that application notes, reference designs, and associated data and information contained in this document

are presented only as guidance for Products use. Therefore, in case you use such information, you are solely

responsible for it and you must exercise your own independent verification and judgment in the use of such information

contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses

incurred by you or third parties arising from the use of such information.

Precaution for Electrostatic

This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper

caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be

applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,

isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).

Precaution for Storage / Transportation

1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:

[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2

[b] the temperature or humidity exceeds those recommended by ROHM

[c] the Products are exposed to direct sunshine or condensation

[d] the Products are exposed to high Electrostatic

2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period

may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is

exceeding the recommended storage time period.

3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads

may occur due to excessive stress applied when dropping of a carton.

4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of

which storage time is exceeding the recommended storage time period.

Precaution for Product Label

QR code printed on ROHM Products label is for ROHM’s internal use only.

Precaution for Disposition

When disposing Products please dispose them properly using an authorized industry waste company.

Precaution for Foreign Exchange and Foreign Trade act

Since our Products might fall under controlled goods prescribed by the applicable foreign exchange and foreign trade act,

please consult with ROHM representative in case of export.

Precaution Regarding Intellectual Property Rights

1. All information and data including but not limited to application example contained in this document is for reference

only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any

other rights of any third party regarding such information or data. ROHM shall not be in any way responsible or liable

for infringement of any intellectual property rights or other damages arising from use of such information or data.:

2. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any

third parties with respect to the information contained in this document.

Other Precaution

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

2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written

consent of ROHM.

3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the

Products or this document for any military purposes, including but not limited to, the development of mass-destruction

weapons.

4. The proper names of companies or products described in this document are trademarks or registered trademarks of

ROHM, its affiliated companies or third parties.

Notice - GE

Rev.002

Daattaasshheeeett

General Precaution

1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.

ROHM shall not be in an y way responsible or liable for failure, malfunction or accident arising from the use of a ny

ROHM’s Products against warning, caution or note contained in this document.

2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior

notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s

representative.

3. The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all

information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or

liable for any damages, expenses or losses incurred by you or third parties resulting from inaccuracy or errors of or

concerning such information.

Notice – WE

Rev.001

BD9470AFM [ROHM]

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