BD9415FS-GE2_技术文档

LED Driver for LCD Backlights

White LED Driver for 4Ch Large LCD Panels

(DC/DC converter type)

BD9415FS

1.1 ●General Description

BD9415FS is a high efficiency driver for white LEDs and

designed for large LCDs. This IC has a built-in boost

DC/DC converter that employs an array of LEDs as the

light source. BD9415FS has various protection functions

against fault conditions, such as over-voltage protection

(OVP), over current limit protection of DC/DC (OCP),

short circuit protection (SCP), over duty protection

(ODP) and open detection of LED string. Therefore,

BD9415FS is available for the fail-safe design over a

wide range of output voltages.

Key Specifications

 Operating power supply voltage： 11.5V to 35.0V

 Oscillator frequency：

 Operating current：

500kHz(RT=30kΩ)

6.2mA (Typ)

-40°C to +105°C

 Operating temperature range：

1.2 Package

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

13.60mm x 7.80mm x 2.01mm

Pin pitch 0.80mm

SSOP-A32

Features

4Ch LED constant current driver (external FET)



Built-in boost DC/DC converter (external FET)

PWM dimming (individual input terminal of 4ch)

Analog dimming (Linear) function

Low heat generation technology

LED protection function (Open/Short protection)

Output Short Protection (OCP)

Over Duty Protection (ODP)

Over Voltage Protection (OVP)

Under Voltage Lockout Protection (UVLO)

Auto restart function

Figure 1. SSOP-A32

Applications

 TV, Computer Display, Notebook, LCD Backlighting.

Typical Application Circuit

VIN

+

VCC

CVCC

32

31

30

29

1

AGND

SSFB

RT

VCC

2

3

4

5

6

7

8

FAILB

UVLO

REG90

CREG90

DUTYP

PWM4 28

PWM3 27

PWM2 26

PWM1 25

LSP 24

PWM4

PWM3

PWM2

PWM1

STB

N

STB

REG90

PGND

CS

9

DUTYON

OVP

23

VREF

10

11

12

13

14

15

16

22

G4

S1

21

LED1

LED4

20

G1

S4

19

S2

G3

18

LED2

G2

LED3

17

S3

Figure 2. Typical Application Circuit

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

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1.3 Pin Configuration

32

31

30

29

1

2

3

4

5

6

7

8

AGND

SSFB

RT

VCC

FAILB

UVLO

REG90

DUTYP

PWM4 28

PWM3 27

STB

N

PWM2

PWM1

LSP

26

25

24

23

22

21

PGND

CS

9

DUTYON

OVP

VREF

10

11

12

13

14

15

16

G4

LED4

S4

S1

LED1

20

19

18

17

G1

S2

G3

LED2

G2

LED3

S3

Figure 3. Pin Configuration

1.4 Pin Descriptions

No.

Name

Pin Name

No.

Function

Power supply terminal

Function

1

2

3

4

5

6

7

VCC

FAILB

UVLO

REG90

STB

32

31

30

29

28

27

26

AGND

SSFB

RT

Analog GND

Error detection output pin (open drain)

Under voltage lockout detection pin

9.0V output voltage pin

IC ON/OFF pin

Soft start pin & Error amplifier pin

DC/DC switching frequency setting pin

DUTYP Over voltage protection setting pin

PWM4

PWM3

PWM2

LED4 External PWM dimming signal input pin

LED3 External PWM dimming signal input pin

LED2 External PWM dimming signal input pin

N

DC/DC switching output pin

Power GND

PGND

DC/DC output current detect pin,

OCP input pin

8

CS

25

PWM1

LED1 External PWM dimming signal input pin

9

DUTYON Over duty protection ON/OFF pin

24

23

22

21

20

19

18

17

LSP

VREF

G4

LED short voltage setting pin

Analog dimming signal input pin

CH4 dimming signal output pin

CH4 LED output pin

10

11

12

13

14

15

16

OVP

S1

Over voltage protection detection pin

CH1 current detection input pin

CH1 LED output pin

LED1

G1

LED4

S4

CH1 dimming signal output pin

CH2 current detection input pin

CH2 LED output pin

CH4 current detection input pin

CH3 dimming signal output pin

CH3 LED output pin

S2

G3

LED2

G2

LED3

S3

CH2 dimming signal output pin

CH3 current detection input pin

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1.5 Block Diagram

COUT

L

Di

CIN

VIN

+

VCC

LED OPEN / SHORT

PROTECT

REG90

STB

OVP

VREG

SCP OVP

FILTER

REG 90

UVLO

FAILB

N

Auto - Restart

Control

CONTROL

LOGIC

DRIVER

CS

CURRENT

SENSE

LEB

+

RT

PWM

COMP

PGND

LED1

OSC

G1

S1

+

-

ERROR

AMP

LED2

-

SSOK

G2

S2

+

-

SSFB

+

LED3

G3

S3

+

-

COMP1

COMP4

LED SHORT

+

-

PROTECT

LED4

G4

S4

+

-

+

-

4V

2800kΩ

LSP

1200kΩ

×6.7

VREF

1/ 5

COMP1

-

LED OPEN

PROTECT

+

COMP4

DUTYON

DUTYP

300kΩ

-

+

Over Duty

Protection

PWM 1

PWM4

AGND

300kΩ

Figure 4. Block Diagram

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1.6 Absolute Maximum Ratings (Ta=25°C)

Rating

-0.3 to +36

60

Unit

V

Parameter

Power Supply Voltage

LED1-4

Symbol

VCC

LED1, LED2, LED3, LED4

FAILB, STB, OVP,

V

FAILB, STB, OVP,

PWM1-4, UVLO, VREF, DUTYON

PWM1, PWM2, PWM3, PWM4,

UVLO, VREF, DUTYON

N, REG90, G1, G2, G3, G4

S1, S2, S3, S4, DUTYP, RT,

SSFB, CS, LSP

20

V

N, REG90, G1-4

13

7

V

S1-4, DUTYP, RT, SSFB, CS, LSP

Power Dissipation

P_d

T_opr

T_jmax

T_stg

0.95 *1

-40 to +105

150

W

°C

Operating Temperature Range

Junction Temperature

Storage Temperature

-55 to +150

(*1) Derate by 7.6mW/°C when operating above Ta=25°C.. (Mounted on 1-layer 70mm x 70mm x 1.6mm board)

1.7 Recommended Operating Conditions (Ta=25°C)

Rating

Unit

Parameter

Power Supply Voltage

DC/DC Oscillating Frequency

VREF Input Voltage

Symbol

VCC

11.5 to 35.0

100 to 1000^(*1)

0.2 to 2.5

V

kHz

V

Fsw

VREF

VLSP

FPWM

LSP Input Voltage

0.8 to 3.0

V

PWM Input Frequency

90 to 2000

Hz

The operating ranges above are acquired by evaluating the IC separately. Please take care when using the IC in

applications.

(*1) When driving external FET as DC/DC, be careful about the input capacity of the FET being used.

1.8 Electrical Characteristics 1/2 (Unless otherwise specified, VCC=24V, Ta=25°C)

Parameter

Symbol

Min

Typ

Max

Unit

Condition

【Total Current Consumption】

VSTB=3.0V, LED1-4=2V,

RT=30kΩ

VSTB=0V

Circuit Current

ICC

-

6.2

14

12.4

25

mA

Standby Current

IST

μA

【Switching Block】

N Pin Source ON Resistance

N Pin Sink ON Resistance

【REG90 Block】

RONH

RONL

-

2.5

3.0

3.75

4.5

Ω

ION=-10mA

ION=10mA

REG90 Output Voltage

REG90 Available Current

REG90

IREG90

8.91

20

9.0

-

9.09

-

V

IO=0mA

mA

VREG=SWEEP DOWN,

VSTB=0V

REG90_UVLO Detect Voltage

REG90_TH

4.7

5.4

6.1

V

【Over Current Limit Protection (OCP) Block】

OCP Detect Voltage

VOCP

0.405

0.450

0.495

VCS=SWEEP UP

【Error Amplifier Block】

Error Amplifier Base Voltage

SSFB Source Current

(Soft Start)

VERR

0.7

-13

0.8

-10

0.9

-7

V

VREF=1.5V

VSSFB=2V

ISSFBSO_S

μA

SSFB Sink Current

SSFB source Current

【CT Oscillator Block】

Oscillation Frequency

MAX DUTY

ISSFBSINK

80

100

120

-85

μA

LED=2.0V、VSSFB=1.0V

LED=0V、VSSFB=1.0V

ISSFBSOUR

-115

-100

µA

FCT

440

91

500

95

560

99

kHz

%

RRT=30kΩ

DUTY_MAX

【Short Circuit protection (SCP) detect Block】

SCP Detect Voltage

VSCP

0.05

0.20

0.35

V

VOVP=SWEEP DOWN

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1.8 Electrical Characteristics 2/2 (Unless otherwise specified, VCC=24V, Ta=25°C)

Parameter

Symbol

Min

Typ

Max

Unit

Condition

VOVP=SWEEP UP

【Over Voltage Protection (OVP) Block】

OVP Detect Voltage

VOVP

2.91

50

3.00

100

0

3.09

200

2

V

OVP Detect Hysteresis

OVP Pin Leak Current

【UVLO Block】

VOVP_HYS

IOVP

mV

µA

VOVP=SWEEP DOWN

VOVP=4.0V

-2

UVLO Unlock Voltage(VCC)

UVLO Hysteresis(VCC)

UVLO Unlock Voltage

UVLO Hysteresis

VUVLO_VCC

VUHYS_VCC

VUVLO

6.5

150

2.375

50

7.5

300

2.5

8.5

600

V

VCC=SWEEP UP

mV

V

VCC=SWEEP DOWN

VUVLO=SWEEP UP

VUVLO=SWEEP DOWN

VUVLO=4.0V

2.625

150

VUHYS

100

600

mV

kΩ

UVLO Input Resistance

【DUTYON Block】

DUTYON Pin HIGH Voltage

DUTYON Pin LOW Voltage

RUVLO

360

840

DTYON_H

DTYON_L

1.5

-

18

V

-0.3

0.8

DUTYON Pin Pull Down

Resistance

【Over Duty Protection (ODP) Block】

PWM ODP Protection Detect

Duty

RDTYON

180

-

300

420

-

kΩ

VDUTYON=3.0V

DODP

35

%

FPWM=120Hz, DUTYP=341kΩ

【Filter Block】

AUTO Timer

TAUTO

TCP

-

163

20

-

ms

FCT=800kHz

Abnormal Detection Timer

【LED Driver Block】

196

294.6

392.8

491

200

300

400

500

0.2

204

305.4

407.2

509

VREF=1.0V

VREF=1.5V

S Pin Voltage

VS

mV

VREF=2.0V

VREF=2.5V

OPEN Detection Voltage

SHORT Detection Voltage

VOPEN

0.12

0.28

V

VLED=SWEEP DOWN

VLED=SWEEP UP,

VLSP=0.895V

VSHORT

5.6

6.0

6.4

VSHORT

_MASK

IVREF

SHORT Mask Voltage

2.8

-2

3.0

0

3.2

2

V

VLED=SWEEP UP

VREF=3.0V

VREF Leak Current

【STB Block】

µA

STB Pin HIGH Voltage

STB Pin LOW Voltage

STB Pull Down Resistance

【PWM Block】

STBH

STBL

RSTB

2.0

-0.3

0.5

-

18

0.8

1.5

V

1.0

MΩ

VSTB=3V

PWM Pin HIGH Voltage

PWM Pin LOW Voltage

VPWM_H

VPWM_L

1.5

-0.3

180

-

18

0.8

420

V

PWM Pin Pull Down Resistance RPWM

300

kΩ

VPWM=3V

【FAILB Block(OPEN DRAIN)】

FAILB LOW Output Voltage

VFAILB_L

0.25

0.5

1.0

V

IFAILB=1mA

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1.9 Typical Performance Curves (Reference data)

14

12

10

8

8.0

7.0

6.0

5.0

4.0

3.0

6

4

STB=3.0V

2.0

PWM=3.0V

STB=3.0V

LED1-4=2.0V

Ta=25°C

STB=3.0V

Ta=25°C

2

REG90=-10mA

1.0

Ta=25°C

0.0

0

5

10

15

20

VCC[V]

25

30

35

10

15

20

25

VCC[V]

30

35

Figure 5. Operating Circuit Current

Figure 6. REG90 Line Regulation

0.6

0.5

0.4

0.3

0.2

0.1

0.0

100

80

60

40

20

0

VCC=24V

Ta=25°C

VCC=24V

Ta=25°C

0

1

2

3

4

0.0

0.5

1.0

1.5

2.0

2.5

3.0

SSFB[V]

VREF[V]

Figure 7. Duty Cycle vs SSFB Character

Figure 8. S Pin Feedback Voltage vs VREF Character

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2.1 Pin Descriptions

○PIN1：VCC

This is the power supply pin of the IC. Input range is from 11.5V to 35V.

The operation starts at more than 7.5V(Typ) and shuts down at less than 7.2V(Typ).

○PIN2：FAILB

This is FAILB signal output (OPEN DRAIN) pin. At normal operation, NMOS will be in OPEN state, during abnormality

detection NMOS will be in ON (500 ohm(Typ))state.

○PIN3：UVLO

Under Voltage Lockout pin is the input voltage of the power stage. IC starts boost operation if UVLO is more than

2.5V(Typ) and stops if lower than 2.4V(Typ). It can also be used for reset when latched off by protection.

The power of step-up DC/DC converter needs to be set detection level by dividing the resistance.

○PIN4：REG90

The REG pin is used in the DC/DC converter driver block to output 9V. Available current is 20mA(Min). Using the REG pin

at current higher than 20mA can affect the IC base voltage, 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.

The characteristic of VCC line regulation at REG90 is shown as [Figure 6]. VCC must be used in more than 11.5V for

stable 9V output. Place the ceramic capacitor connected to REG90 pin (2.2uF to 10uF) closest to REG90-AGND pin.

○PIN5：STB

This is the ON/OFF setting terminal of the IC. It is allowed for use to reset the IC from shutdown.

※The IC state is switched according to voltages input in the STB pin.

※Avoid using the STB pin between two states (0.8 to 2.0V).

○PIN6：N

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 0V to 9V. Output ON resistance H - side is 2.5Ω (Typ) and L-side is 3.0Ω (Typ).

Frequency can be set by the resistor connected to RT. Refer to <RT> pin description for the frequency setting.

○PIN7：PGND

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

○PIN8：CS

CS pin is current detector for DC/DC current mode inductor current control pin.

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

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

also incorporates the over current protection (OCP) function. If the CS voltage reaches 0.45V(Typ) or more, switching

operation will be forced to stopped.

○PIN9：DUTYON

This is the ON/OFF setting terminal of the LED PWM Over Duty Protection (ODP). By adjusting DUTYON input voltage, it

is ON/OFF of the ODP adjusted.

State

DUTYON input voltage

DUTYON= -0.3V to +0.8V

DUTYON= +1.5V to +18.0V

ODP=ON

ODP=OFF

○PIN10：OVP

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

of it exceeds 3.0V(Typ), N pin will stop. This case is not CP count. When OVP pin voltage <0.2V(Typ) or lower, short

circuit protection (SCP) function is activated, and output of gate driver will become low immediately. And system is

stopped after a CP count. The setting example is separately described in the section ”3.2.6 OVP Setting”.

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○PIN11, 14, 17, 20 ：S1-S4, PIN23 ： VREF

LED constant current driver is connected to the source of bill FET outside. Output current ILED is inversely proportional to

the resistance value. This is the input pin for analog dimming signal. Output current ILED is directly proportional to the

input voltage value. VREF pin is high impedance because the internal resistance is not connected to a certain bias.

Even if VREF function is not used, pin bias is still required because the open connection of this pin is not a fixed potential.

VREF pin voltage is set as 「V_VREF」, LED current 「I_LED」can be calculated as below.

VREF [V]

ILED[A] 

0.2ꢀꢀ

RS[Ω]

ILED

LED

G

VREF 1.2V, RS  2[]

ILED 120[mA]ꢀ

+

-

S 240mV

RS

Figure 9. ILED setting example

For the adjustment of LED current with analog dimming by VREF, note that the output voltage of the DC/DC converter

largely changes accompanied by LED VF changes if the VREF voltage is changed rapidly. In particularly, when the VREF

voltages changed from high to low, it makes the LED terminal voltage seem higher transiently, which may influence

application such as activation of the LED short circuit protection. It needs to be adequately verified with an actual device

when analog dimming is used.

○PIN12, 15, 18, 21：LED1-LED4

LED constant current driver output pins. Drain of external NMOS is connected. Setting of LED current value is adjustable

by setting the VREF voltage and connecting a resistor to S pin. For details, see the explanation of <PIN:11, 14, 17, 20 S1

- S4, Pin23 : VREF >.

The abnormal voltage of this pin activates the protection function of LED OPEN detection, LED SHORT detection.

Please refer to < 2.2 List of The Protection Function Detection Condition> for details.

○PIN13, 16, 19, 22：G1-G4

This is the output terminal for driving the gate of the boost MOSFET. The high level

is REG90. Frequency can be set by the resistor connected to RT. Refer to <RT> pin description for the frequency setting.

○PIN24：LSP

LED Short detection voltage setting pin. Resistance voltage divider is internally on IC. It is set as 1.2V.

When need to establish the other voltage, use an external resistance voltage divider.

LSP pin voltage is set as LED SHORT PROTECTION detection voltage and can be calculated as below.

LED_SHORT 6.7VLSP[V]ꢀ

LED_SHORT：LSP detection voltage, VLSP：LSP pin voltage

Set LSP voltage in the range of 0.8V to 3.0V.

In addition to considering the voltage of the internal resistance voltage divider, it's necessary to establish the voltage of

the LSP terminal.

○PIN25, 26, 27, 28：PWM1-PWM4

These are the PWM dimming signal input terminals. The high / low level of PWM pins are the following.

State

PWM pin voltage

PWM= +1.5V to +18.0V

PWM= -0.3V to +0.8V

PWM=H

PWM=L

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○PIN29：DUTYP

This is the ODP setting pin. The ODP (Over Duty Protection) is the function to limit DUTY of LED PWM frequency fPWM

by ODP detection Duty (ODPduty) set by resistance (RDUTY) connected to DUTYP pin.

○Relationship between LED PWM frequency fPWM, ODP Detection Duty and DUTYP resistance (ideal)

1172ODP [%]

duty

R_DUTYP



[k]ꢀ

f_PWM[Hz]

The RDUTYP setting ranges from 15kΩ to 600kΩ.

The setting example is separately described in section ”3.2.6 ODP Setting”.

○PIN30：RT

This is the DC/DC switching frequency setting pin. DCDC frequency is decided by connected resistor.

○The relationship between the frequency and RT resistance value (ideal)

15000

R_RT

[k]ꢀ

f_SW[kHz]

○PIN31：SSFB

The SSFB pin is used to make setting of soft start time and duty for soft start, and DC/DC current mode control error

amplifier. It performs constant current charge of 10uA to the external capacitor connected to SSFB terminal, which

enables soft-start of DC/DC converter.

The SSFB pin detects the voltages of LED pins (1 to 4) and controls inductor current so that the pin voltage of the LED

located in the row with the highest Vf will come to 0.8V(Typ) (VREF=1.5V). As a result, the pin voltages of other LEDs

become higher by Vf variation. After completion of soft start, the SSFB pin is put into high-impedance state with the PWM

signal being in the low state, thus maintaining the SSFB voltage.

Since the LED protection function (OPEN/SHORT detection) works when it turns to the LED feedback mode.

○PIN32：AGND

This is the GND pin of the IC.

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2.2 List of the Protection Function Detection Condition (Typical Condition)

Detection Condition

Protection

Function

Detection

Release

Condition

LEDx > 0.2V^(*2)

(3clk)

LEDx < 6.7xVLSP Auto Restart in

Protection Type

Detection Condition

SS

PWM

After

Soft start

Auto Restart in

relevant CH

LED Open

LED Short

LEDx

Sx

LEDx < 0.2V

LEDx > 6.7×VLSP

Sx > 0.6V

H(4clk)

After

Soft start

H(4clk)

(3clk)

relevant CH

LED Driver

FET D-S Short

Whole Auto

Restart

―

Sx < 0.6V

LEDx < 0.2V

And

LEDx > 0.2V

Or

SSFB < 3.6V

LED GND

Short

Whole Auto

Restart

LEDx

H

SSFB > 4.0V

Return

OVP

SCP

OVP

OVP > 3.0V

OVP < 0.2V

VCC < 7.2V

UVLO < 2.4V

―

OVP < 2.9V

OVP > 0.25V

VCC > 7.5V

UVLO > 2.5V

immediately.

Whole Auto

Restart

Return

immediately.

Return

immediately.

Return

VCCUVLO

UVLO

VCC

UVLO

OCP

CS

CS > 0.45V

―

immediately.

(Pulse by Pulse)

DUTYON = H

And

PWM interval > setting

by DUTYP resistor

Over PWM

duty^(*1)

Return

immediately.

PWM

H

The clock number of timer operation corresponds to the boost pulse clock.

(*1)When PWM Duty count starts, PWM=H → L is input, when PWM=L → H is input, the ODP is reset.

The G (1 to 4) output, the N pin output maintain L until PWM=H → L is input in PWM = 100% again when ODP works once.

(*2) The release condition of OPEN protection depends on its release timing.

No.

1

The timing of release of LEDx voltage (LEDx > 0.2V)

LED pin voltage is released during PWM=H.

The Release Condition

LED pin voltage is normal range during 3clk (3 positive edge)

As PWM=L, LED pin voltage do not exceed Short protection

voltage (VLSP) during more than 3clk or PWM positive edge is

input when LED pin voltage do not exceed VLSP for more than

3clk.

2

LED pin voltage is released during PWM=L.

2.3 List of Protection function

Protection function

Operation of the Protection Function

DC/DC Gate

Output

Stop N output

LED Driver

Soft-start

FAILB Pin

HiZ

STB

Stop immediately

Discharge immediately

Normal operation

(Stop when all LED

CH stop)

Stop after 2¹⁴count

Stop in relevant CH

Stop after 2¹⁴count

Stop in relevant CH

LED Open

Normal operation

Low after timer latch

LED Short

Normal operation

Low after timer latch

LED Driver

FET D-S Short

Stop after 2¹⁴count

Discharge after stop

Only detected LED ch

stops after CP count

Other LED ch stop

operation

Stop after

（CP^*+2⁶） Discharge

LED GND Short

Low after timer latch

(CP^*+2⁶)count

after count

after（CP^*+2⁶）count

VCCUVLO

UVLO

OVP

Stop N output

Stop immediately

Normal operation

Discharge immediately

Normal operation

HiZ

SCP

Normal operation

Low after timer latch

Stop N output

(Pulse by Pulse)

Normal operation

OCP

Normal operation

HiZ

Over PWM duty

Stop in relevant CH

※CP ： Count movement after detection of D-S SHORT, LED_OPEN, SHORT.

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3.1 Application Circuit Example

An example application using the BD9415FS.

3.1.1 Basic Application Example

VIN

+

VCC

CVCC

32

31

30

29

1

2

3

4

5

6

7

8

AGND

SSFB

RT

VCC

FAILB

UVLO

REG90

CREG90

DUTYP

PWM4 28

PWM3 27

PWM2 26

PWM4

PWM3

PWM2

PWM1

STB

N

STB

REG90

PGND

CS

25

PWM1

LSP 24

9

DUTYON

OVP

23

VREF

10

11

12

13

14

15

16

22

G4

S1

21

LED1

LED4

20

G1

S4

19

S2

G3

18

LED2

G2

LED3

17

S3

Figure 10. Basic Application Example

3.1.2 Application Example of Unused CH

VCC

+

( )

CVCC

32

31

30

29

1

2

3

4

5

6

7

8

AGND

SSFB

RT

VCC

FAILB

UVLO

REG90

CREG90

DUTYP

PWM4 28

PWM3 27

PWM2 26

PWM4

STB

N

STB

REG90

PWM3

PWM2

PWM1

REG90

PGND

CS

25

PWM1

LSP 24

9

DUTYON

OVP

23

VREF

10

11

12

13

14

15

16

22

G4

S1

21

LED1

LED4

20

G1

S4

19

S2

G3

LEDunused

18

LEDunused

LED2

G2

LED3

17

S3

Figure 11. Application Example of Unused CH

When an LED terminal was unused, please dispose the unused CH as follows.

・Please input lower than 3.0V (typical) of voltage to a LEDx pin (ex. 1.0 to 2.0V).

・Gx pin, Sx pin is short

・Unused PWMx = L

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3.2 External Components Selection

3.2.1 Startup operation and soft start (SSFB) capacitance setting

The following section describes the sequence for the startup of this IC.

①

5V

VOUT

Q

D

PWM

COMP

STB

Soft-Start(ISS=10uA)

IFB(Sink, Source)=±100uA)

N

DRIVER

OSC

CS

SSFB

PWM

N

LED_OK

LEDx

SSFB

②

R^SSFB

C^SSFB

VOUT

ILED

Gx

③

Sx

LED_ DRIVER

PWMx

④

LED_OK

⑥

⑤

Figure 12. Startup Waveform

Figure 13. Circuit Behavior at Startup

 Description of startup sequence

(1) Set the STB and PWM pin to “ON”.

(2) Set all systems to “ON”, SSFB charge will be initiated.

(3) Since the SSFB pin reach the lower limit of the internal sawtooth wave of the IC, the DC/DC converter operates to

start VOUT voltage rising.

(4) The VOUT voltage continuously rising to reach a voltage at which LED current starts flowing.

(5) When the LED current reaches the set amount of current, the startup operation is completed.

(6) After that, conduct normal operation following the feedback operation sequence with the LED pins.

If the SSFB pin sink/source current is ±100uA, the LED protection function will be activated.

 SSFB capacitance setting procedure

As aforementioned, this IC stops DC/DC converter when the PWM pin is set to Low level and conducts step-up operation

only in the section in which the PWM pin is maintained at High level. Consequently, setting the PWM duty cycle to the

minimum will extend the startup time. The startup time also varies with application settings of output capacitance, LED

current, output voltage, and others.

Startup time at minimum duty cycle can be approximated according to the following method:

Make measurement of VOUT startup time with a 100% duty cycle, first. Take this value as “Trise100”.

The startup time “Trise_min” for the relevant application with the minimum duty cycle is given by the following equation.

T_{rise_100}[sec]

T_{rise_ min}



[sec]

Min _ Duty [ratio]

However, since this calculation method is just for approximation, use it only as a guide.

Assuming that the SSFB pin voltage is VSSFB, the time is given by the following equation:

C_SSFB[F]VSSFB[V]

T_SSFB



[Sec]

10[A]

As a result, it is recommended to make SSFB capacitance setting so that “TSSFB” will be greater than “Trise_min”

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3.2.2 LED Current Setting (VREF pin, Sx pin)

First, VREF pin voltage is determined. When performing Analog dimming, be careful of VREF pin input range(0.2 to 2.5V)

and decide typical voltage.

In BD9415FS, LED constant current is controlled by Sx pin voltage as a reference point. Sx pin is controlled to become

one fifth of the voltage of VREF pin voltage. In the case of VREF=1V, it is set to Sx=0.2V.

Therefore, when the resistance to Sx pin versus GND is set to "RS", the relationship between RS, VREF and ILED is as

follows

V_VREF[V ]

R_S[ohm] 

I_LED[A]5

REG90=9V

4V

3.2.3 LED Short Detection Voltage Setting (LSP terminal)

R3

2800k

R1

R2

The voltage of LED short detection can be arbitrarily set up with LSP

pin voltage. It is possible to change the LED short detection voltage,

please input (0.8V to 3.0V) to LSP pin.

About LED short detection voltage, if "VLEDshort" and LSP pin

voltage are set to "VLSP", it is as follows

LSP

COMP

LSP

+

-

R4

1200k

CLSP

LEDx

3700k

800k

VLED_SHORT[V]

V_LSP



6.7

Figure 14. LSP setting example

Since the setting range of a LSP pin is set to 0.8V to 3.0V, VLEDshort can be set up in 5.36V to 20.1V.

○ Equation of setting LSP detect Voltage

When the detection voltage VLSP of LSP is set up by resistance division of R1 and R2 using REG90,

it becomes like the following formula.



R2[k] R4[k]



REG90[V] R3 4[V] R1[k]





LED_SHORT 

6.7 [V]ꢀ(2)





(R1[k] R3[k] R2  R4





 R2[k] R4[k] R1[k] R3[k]









【Setting example】

Assuming that LSP is approximated by Equation (1) in order to set LSP detection voltage to 6V, R1 comes to 68kΩ. and

R2 comes to 7.6kΩ.

When calculating LSP detection voltage taking into account internal IC resistance by Equation (2), it will be given as:



7.6[k]1200[k]



9[V]2800[k] 4[V]68[k]





LED_SHORT 

 6.7  6.078[V]ꢀ(2)





(68[k]2800[k] 7.6[k]1200[k]





 7.6[k]1200[k] 68[k] 2800[k]









*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant

setup, and inquire enough to it.

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3.2.4 DCDC Oscillation Frequency Setting

RRT which connects to RT pin sets the oscillation frequency f_SWof DCDC.

○Relationship between frequency f_SWand RT resistance (ideal)

Frequency(fsw)

15000

R_RT

[k]ꢀ

f_SW[kHz]

【setting example】

When DCDC frequency f_SWis set to 200kHz, R_RTis as follows.

GATE

CS

RT

Rcs

R_RT

15000

GND

R_RT



 75[k]ꢀ

f_SW[kHz] 200[kHz]

Figure 15. RT terminal setting example

Vin

3.2.5 UVLO Setting

Under Voltage Lockout pin is the input voltage of the power stage. IC starts boost

operation if UVLO is more than 2.5V(Typ) and stops if lower than 2.4V(Typ).

Since internal impedance exists in UVLO pin, cautions are needed for selection of

resistance for resistance division.

Vin detection voltage level can be calculated by the following formula using

resistance division of R1 and R2 (unit: kΩ).

R1

R2

Zin=610kΩ

(typ.)

UVLO

1400k

530k

480k

1000pF

AGND AGND

125k

Figure 16. UVLO setting example

○ Equation of Setting UVLO Release

R1 R2

1















Vin_DET 2.5



 R1 [V]ꢀ







R2

1400k 125k 530k  480k



○ Equation of Setting UVLO Lock

R1 R2

1









Vin_lock 2.4



 R1 [V]ꢀ









R2

1400k 125k 530k  480k  40k







*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant

setup, and inquire enough to it.

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3.2.6 OVP Setting

The OVP terminal is the input for over-voltage protection of output voltage.

The OVP pin is high impedance, because the internal resistance is not connected to a certain bias.

Detection voltage of VOUT is set by dividing resistors R1 and R2. The resistor values can be calculated by the formula

below.

○ OVP Detect Equation

VOUT

If VOUT is boosted abnormally, VOVPDET, the detect voltage

of OVP, R1, R2 can be expressed by the following formula.

R1

R2



VOVP_DET[V] 3.0[V]



[k]ꢀ

OVP

R1 R2[k]

+

-

3.0[V]

3.0V/2.9V

○ OVP Release Equation

By using R1 and R2 in the above equation, the release voltage

of OVP, VOVPCAN can be expressed as follows.

OVP COMP

SCP COMP

-

+

0.2V



R1[k] R2[k]

R2[k]



ꢀ

VOVP  2.9[V]

CAN

Figure 17 . OVP setting example

【setting example】

If the normal output voltage, VOUT is 58V, the detect voltage of OVP is 63V, R2 is 20kΩ, R1 is calculated as follows.



VOVP_DET[V] 3.0[V]





63[V] 3.0[V]



R1 R2[k]

 20[k]ꢀ

 400[k]

3.0[V]

By using these R1 and R2, the release voltage of OVP, VOVPCAN can be calculated as follows.



R1[k] R2[k]

R2[k]





400[k] 20[k]



VOVP  2.9[V]

ꢀ 2.9[V]

 60.9[V]

CAN

20[k]

3.2.7 SCP setting

【3.2.6) The SCP setting「VSCPDET」 voltage is calculated as below when R1,R2 is decided above:



R1[k] R2[k]





400[k] 20[k]



VSCP_DET 0.2[V]

ꢀ 0.2[V]

 40.2[V]

R2[k]

20[k]

*Also including the variation in IC, please also take the part variation in a set into consideration for an actual constant

setup, and inquire enough to it.

3.2.8 FAILB Logic

FAILB signal output pin (OPEN DRAIN); when an abnormality is detected, NMOS is brought into GND Level.

The rating of this pin is 20V.

State

FAILB output

In completion of an

abnormality

GND Level

(500ohm (Typ))

（After CP count^※）

In normal state, In STB

OPEN

※CP count ： Count movement after detection of D-S SHORT, LED_OPEN, SHORT, SCP.

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3.2.9 ODP setting

RDUTYP which connects to ODP pin sets the ODP detection duty.

○Relationship between LED PWM frequency f_PWM, ODP Detection Duty and DUTYP resistance (ideal)

1172ODP [%]

duty

R_DUTYP



[k]ꢀ

f_PWM[Hz]

N

DUTYP

PWM

CS

【setting example】

When LED PWM frequency f_PWM, is set to 120Hz and ODP

Detection Duty (ODPduty) is set to 35%, RDUTYP is as follows.

R_DUTYP

R_CS

Gx

Sx

1172 35[%]

R_DUTYP



 341.8[k]ꢀ

120[Hz]

R_S

GND

Figure 18. ODP setting example

fPWM

PWM

N

GATE

Gx

DIMOUT

ODPduty

Figure 19. The GATE and the DIMOUT waveform as PWM dimming (ODP)

3.2.10 Timer Latch Time (CP Counter) Setting, Auto-Restart Timer Setting

Timer latch time (CP Counter) is set by counting the clock frequency which is set at the RT pin. About the behavior from

abnormal detection to latch-off, please refer to the section “3.5.2 and 3.5.3 Timing Chart”.

When various abnormal conditions happen, counting starts from the timing, latch occurs after below time has passed.

Furthermore, even if PWM=L, if abnormal condition continues, timer count will not reset.

R_RT[]

100[k]

1.510⁷

LATCH_TIME 2¹⁴

16384 

 [s]ꢀ

1.510¹⁰

R_RT[]

100[k]

1.510⁷

AUTO_TIME 2¹⁷

 131072 

[s]ꢀ

1.510¹⁰

Here, LATCHTIME = time until latch condition occurs, AUTOTIME = auto restart timer’s time

RRT = Resistor value connected to RT pin

【setting example】

Timer latch time when RT=30kohm (500kHz)

R_RT[k]

30[k]

LATCH_TIME16384 

16384 

 32.8[ms]ꢀ

1.510⁷

R_RT[k]

30[k]

AUTO_TIME 131072 

 131072 

 262.1[ms]ꢀ

1.510⁷

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3.3. DCDC Parts Selection

3.3.1. OCP Setting / Calculation Method for the Current Rating of DCDC Parts

OCP detection stops the switching when the CS pin voltage is more than 0.45V(Typ). The resistor value of CS pin, RCS

needs to be considered by the coil L current. And the current rating of DCDC external parts is required more than the

peak current of the coil.

Shown below are the calculation method of the coil peak current, the selection method of Rcs (the resistor value of CS

pin) and the current rating of the external DCDC parts at Continuous Current Mode.

(The calculation method of the coil peak current, I_PEAKat Continuous Current Mode)

At first, since the ripple voltage at CS pin depends on the application

condition of DCDC, the following variables are used.

Vout voltage = VOUT [V]

LED total current = IOUT [A]

L

VOUT

DCDC input voltage of the power stage = VIN [V]

Efficiency of DCDC =η [%]

VIN

IL

And then, the average input current IIN is calculated by the following

equation.

fsw

V_OUT[V ] I_OUT[A]

I_IN



[A]ꢀ

V_IN[V ][%]

GATE

And the ripple current of the inductor L (ΔIL[A]) can be calculated by

CS

using DCDC the switching frequency, f_SW, as follows.

Rcs

GND

(V_OUT[V ]V_IN[V]) V_IN[V ]

L[H]V_OUT[V] f_SW[Hz]

IL 

[A]ꢀ

(V)

On the other hand, the peak current of the inductor I_PEAKcan be expressed

as follows.

IL[A]

… (1)

I_PEAK I_IN[A]

[A]ꢀ

2

Therefore, the bottom of the ripple current I_MINis

（A)

(t)

IL[A]

I_min I_IN[A]

ꢀ

or 0

Ipeak

2

ΔIL

IIN

If I_MIN>0, the operation mode is CCM (Continuous Current Mode),

otherwise the mode is DCM (Discontinuous Current Mode).

Imin

(The selection method of R_CSat Continuous Current Mode)

I_PEAKflows into R_CSand that causes the voltage signal to CS pin. (Please

refer to the timing chart at the right)

(t)

（V)

Peak voltage VCS_PEAKis as follows.

0.4V

0.45V

VCS_PEAK R_CS I_PEAK[V]ꢀ

VCSpeak

As this VCS_PEAKreaches 0.4V (typical), the DCDC output stops the

switching.

Therefore, R_CSvalue is necessary to meet the condition below.

(t)

R_CS I_PEAK[V]  0.45[V]ꢀ

Figure 20. Coil Current Waveform

(The current rating of the external DCDC parts)

The peak current as the CS voltage reaches OCP level (0.4V (Typ)) is defined as I_{PEAK_DET}

.

0.45[V ]

R_CS[]

… (2)

I_{PEAK _ DET}



[A]ꢀ

The relationship among I_PEAK(equation (1)), I_{PEAK_DET}(equation (2)) and the current rating of parts is required to meet

the following

I

 I



The current rating of parts

peak

peak _det

Please make the selection of the external parts such as FET, Inductor, diode meet the above condition.

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【setting example】

Output voltage = V_OUT[V] = 40V

LED total current = I_OUT[A] = 0.48A

DCDC input voltage of the power stage = VIN [V] = 24V

Efficiency of DCDC=η [%]=90%

Averaged input current I_INis calculated as follows.

V_OUT[V] I_OUT[A] 40[V]0.48[A]

I_IN



 0.89[A]ꢀ

V_IN[V][%]

24[V]90[%]

If the switching frequency, f_SW= 200kHz, and the inductor, L=100μH, the ripple current of the inductor L (ΔIL [A]) can be

calculated as follows.

(V_OUT[V]V_IN[V]) V_IN[V]

(40[V] 24[V]) 24[A]

IL 



 0.48[A]ꢀ

L[H]V_OUT[V] f_SW[Hz] 10010^6[H]40[V]20010³[Hz]

Therefore the inductor peak current, I_PEAKis

IL[A]

0.48[A]

I_PEAK I_IN[A]

[A]  0.89[A]

1.13[A]ꢀ

…calculation result of the peak current

…R_CSvalue confirmation

2

If R_CSis assumed to be 0.3Ω

VCS_PEAK R_CS I_PEAK 0.3[]1.13[A]  0.339[V] 0.45[V]

The above condition is met.

And I_{PEAK_DET}, the current OCP works, is

0.45[V ]

I_{PEAK _ DET}



 1.35[A]

0.3[]

If the current rating of the used parts is 2A,

 I 

…current rating confirmation of DCDC

parts

I

The current raying 1.33[A]1.35[A] 2.0[A]

peak

peak _det

This inequality meets the above relationship. The parts selection is proper.

And I_MIN, the bottom of the IL ripple current, can be calculated as follows.

IL[A]

I_MIN I_IN[A]

[A] 1.13[A] 0.48[A]  0.65[A]  0ꢀ

2

This inequality implies that the operation is continuous current mode.

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3.3.2. Inductor Selection

The inductor value affects the input ripple current, as shown the previous section 3.3.1.

(V_OUT[V ]V_IN[V ])V_IN[V]

L[H]V_OUT[V ] f_SW[Hz]

IL 

[A]ꢀ

ΔIL

V_OUT[V ] I_OUT[A]

 [A]ꢀ

I_IN

V_IN[V ][%]

V_IN

IL[A]

I_PEAK I_IN[A]

[A]ꢀ

2

I_L

L

Where

V_OUT

L: coil inductance [H]

V_IN: input voltage [V]

V_OUT: DCDC output voltage [V]

I_OUT: output load current (the summation of LED current) [A]

I_IN: input current [A] f_SW: oscillation frequency [Hz]

R_CS

C_OUT

Figure 21. Inductor current waveform and diagram

In continuous current mode, ⊿IL is set to 30% to 50% of the output load current in many cases.

In using smaller inductor, the boost is operated by the discontinuous current mode in which the coil current returns to

zero at every period.

*The current exceeding the rated current value of inductor flown through the coil causes magnetic saturation, results in

decreasing in efficiency. Inductor needs to be selected to have such adequate margin that peak current does not

exceed the rated current value of the inductor.

*To reduce inductor loss and improve efficiency, inductor with low resistance components (DCR, ACR) needs to be

selected.

3.3.3. Output Capacitance C_OUTSelection

Output capacitor needs to be selected in consideration of equivalent series resistance

required to even the stable area of output voltage or ripple voltage. Be aware that set

V_IN

LED current may not be flown due to decrease in LED terminal voltage if output ripple

component is high.

Output ripple voltage _V_OUTis determined by Equation (4):

I_L

L

V_OUT

V_OUT ILR_ESR[V]ꢀ



(4)

R_ESR

C_OUT

When the coil current is charged to the output capacitor as MOS turns off, much output

ripple is caused. Much ripple voltage of the output capacitor may cause the LED current

ripple.

R_CS

Figure 22. Output capacitor diagram

* Rating of capacitor needs to be selected to have adequate margin against output voltage.

* To use an electrolytic capacitor, adequate margin against allowable current is also necessary. Be aware that the LED

current is larger than the set value transitionally in case that LED is provided with PWM dimming especially.

3.3.4. MOSFET Selection

There is no problem if the absolute maximum rating is larger than the rated current of the inductor L, or is larger than

the sum of the tolerance voltage of C_OUTand the rectifying diode VF. The product with small gate capacitance (injected

charge) needs to be selected to achieve high-speed switching.

* One with over current protection setting or higher is recommended.

* The selection of one with small on resistance results in high efficiency.

3.3.5. Rectifying Diode Selection

A schottky barrier diode which has current ability higher than the rated current of L, reverse voltage larger than the

tolerance voltage of C_OUT, and low forward voltage VF especially needs to be selected.

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3.4 Loop Compensation

A current mode DCDC converter has each one pole (phase lag) f_Pdue to CR filter composed of the output capacitor and

the output resistance (= LED current) and zero (phase lead) f_Zby the output capacitor and the ESR of the capacitor.

Moreover, a step-up DCDC converter has RHP zero (right-half plane zero point) f_ZRHPwhich is unique with the boost

converter. This zero may cause the unstable feedback. To avoid this by RHP zero, the loop compensation that the

cross-over frequency fc, set as follows, is suggested.

fc = f_ZRHP/5 (f_ZRHP: RHP zero frequency)

Considering the response speed, the calculated constant below is not always optimized completely. It needs to be

adequately verified with an actual device.

VIN

VOUT

L

ILED

VOUT

-

+

FB

gm

RESR

COUT

RFB1

CFB1

CFB2

RCS

Figure 23. Output stage and error amplifier diagram

i.

Calculate the pole frequency f_Pand the RHP zero frequency fZRHP of DC/DC converter

V_OUT(1 D)²

2  L  I_LED

I_LED

f_P

[Hz]

f_ZRHP



[Hz]

2 V_OUTC_OUT

V_OUTV_IN

I_LED



the summation of LED current, D 

Where

(Continuous Current Mode)

V_OUT

ii.

Calculate the phase compensation of the error amp output(f_c= f_ZRHP/5)

f_RHZP R_CS I_LED

5 f_P gm V_OUT(1 D)

R_FB1



[]

1

5

C_FB1



[F]

2  R_FB1 f_C2  R_FB! f_ZRHP

gm  4.010^4[S]

Above equation is described for lighting LED without the oscillation. The value may cause much error if the quick

response for the abrupt change of dimming signal is required.

To improve the transient response, RFB1 needs to be increased, and CFB1 needs to be decreased. It needs to be

adequately verified with an actual device in consideration of variation from parts to parts since phase margin is

decreased.

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3.5. Timing Chart

3.5.1 PWM Start Up

7.5V

VCC

2.0V

0.8V

STB

5.8V

REG90

2.5V

UVLO

FAILB

(External PullUp)

SSFB

LED_OK

(internal)

VOUT

PWMx

ILEDx

LED Open Detection

LED Short Detection

OFF

NORMAL

OFF

(*1) (*2) (*3)

(*4)

(*5)

Figure 24. Start Up

(*1)…REG90 starts up when STB is changed from Low to High. In the state where the PWM signal is not inputted, SS terminal

is not charged and DCDC doesn't start to boost, either.

(*2)…When REG90 is more than 5.8V(Typ), the reset signal is released.

(*3)…The charge of the pin SS starts at the positive edge of PWM=L to H, and the soft start starts. The pin SS continues

charging in spite of the assertion of PWM or OVP level.

(*4)…The soft start interval will end if the LED_OK = H (internal signal), By this time, it boosts VOUT to the voltage where the

set LED current flows. The abnormal detection of FBMAX starts to be monitored.

(*5)…As STB=L, the boost operation is stopped instantaneously.( N=L, SSFB=L)

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3.5.2 LED OPEN Detection

PWM1~4

LED1=Normal

Condition

LED1≒Vout

LED1=OPEN

0.2V

5V Pull Up

LED1=OPEN

0.2V

OPEN

THRFESHOLD

VLED1

LED1=Normal

Condition

3V

VLED2~4

Internal signal

(OPEN DET)

Mask

(4count)

16384count

16384

Mask

Ab

normal

<

count

Internal signal

(Abnormal Count)

(3count)

LED1=OFF

ILED1

ILED2~4

FAILB

131072count

Internal signal

AUto Restart Count Start

(131072count)

(Auto Restart)

Abnormal

Counting

Abnormal

Counting

Normal

LED1 = OFF

Normal

IC State

Judge OK

Figure 25. LED OPEN Detection

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3.5.3 LED SHORT Detection

PWM1~4

LED1=Normal

Condition

LED1=Normal

Condition

LED1=SHORT

6V

VLED1

6V

VLED2~4

Internal signal

(SHORT DET)

Mask

(4counts)

16384

<

Ab

normal

16384count

count

Mask

Internal signal

(Abnormal Count)

(3counts)

ILED1

ILED2~4

FAILB

LED1 = OFF

131072count

Internal signal

AUto Restart

Count Start

(131072count)

(Auto Restart)

Abnormal

Counting

Abnormal

Counting

Abnormal

Counting

Normal

LED1 = OFF

IC State

Normal

Judge Fail

Judge OK

Figure 26. LED SHORT Detection

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3.5.4 Over Duty Protection

PWM=100%

PWM1

(35%)

(30%)

dutyH > (35%)

PWM2

PWM3

PWM4

(35%)

ILED1

(35%)

(30%)

ILED2

ILED3

ILED4

(*1)

(*2) (*3)

(*4)

(*5)

(*6)

Figure 27. Over Duty Protection

ODP=35% setup

(*1) …PWM < 35% : Turn on in relevant CH of same time PWM_DutyH.

(*2) …PWM > 35% : An LED of relevant CH is turn off by PWM_DutyH=35%.

(*3) …PWM=H signal beyond 35% is changed, and that doesn't react to IC in particular.

(*4) …PWM > 35% : An LED of relevant CH is turn off by PWM_DutyH=35%.

(*5) …ODP Function= ON : When a PWM signal is equivalent to 100%, LED=OFF continues after 35 %.

(*6) … When the next PWM=H signal is input, an LED is also turn on at the same time.

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3.6 I/O Equivalent Circuits

OVP

UVLO

SSFB

OVP

100k

5V

UVLO

RT

PWM1-4

DUTYON

PWM1-4

DUTYON

100 k

100k

300k

RT

5V

300k

G1-4

S1-4

LSP

4V

G1-G4

2800k

100k

LSP

S1-S4

1200k

REG90 / N / PGND / CS

STB

VREF

REG90

N

STB

VREF

100k

20k

5V

1M

GND

CS

DUTYP

FAILB

LED1-4

DUTYP

FAILB

500

Figure 28. Internal Equivalent Circuits

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Operational Notes

1.

2.

Reverse Connection of Power Supply

Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when

connecting the power supply, such as mounting an external diode between the power supply and the IC’s power

supply pins.

Power Supply Lines

Design the PCB layout pattern to provide low impedance supply lines. Connect a capacitor to ground at all power

supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic

capacitors.

3.

4.

Ground Voltage

Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.

Ground Wiring Pattern

When using both small-signal and large-current ground traces, the two ground traces should be routed separately but

connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal

ground caused by large currents. Also ensure that the ground traces of external components do not cause variations

on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.

5.

Thermal Consideration

Should by any chance the maximum junction temperature rating be exceeded the rise in temperature of the chip may

result in deterioration of the properties of the chip. In case of exceeding this absolute maximum rating, increase the

board size and copper area to prevent exceeding the maximum junction temperature rating.

6.

7.

Recommended Operating Conditions

These conditions represent a range within which the expected characteristics of the IC can be approximately

obtained. The electrical characteristics are guaranteed under the conditions of each parameter.

Inrush Current

When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may

flow instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power

supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring,

and routing of connections.

8.

9.

Operation Under Strong Electromagnetic Field

Operating the IC in the presence of a strong electromagnetic field may cause the IC to malfunction.

Testing on Application Boards

When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may

subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply

should always be turned off completely before connecting or removing it from the test setup during the inspection

process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during

transport and storage.

10. Inter-pin Short and Mounting Errors

Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in

damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.

Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment)

and unintentional solder bridge deposited in between pins during assembly to name a few.

11. Unused Input Pins

Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and

extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small

charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and

cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the

power supply or ground line.

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12. Regarding the Input Pin of the IC

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 intersection of the P layers with the N layers of other elements, creating a

parasitic diode or transistor. For example (refer to figure below):

When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.

When GND > Pin B, the P-N junction operates as a parasitic transistor.

Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual

interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to

operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should

be avoided.

Resistor

Transistor (NPN)

Pin A

Pin B

B

E

C

Pin A

B

C

E

P

P⁺

N

P⁺

P

P⁺

N

Parasitic

Elements

Parasitic

Elements

P Substrate

GND GND

P Substrate

GND

Parasitic

Elements

Parasitic

Elements

N Region

close-by

Figure 29. Example of monolithic IC structure

13. Ceramic Capacitor

When using a ceramic capacitor, determine the dielectric constant considering the change of capacitance with

temperature and the decrease in nominal capacitance due to DC bias and others.

14. Area of Safe Operation (ASO)

Operate the IC such that the output voltage, output current, and the maximum junction temperature rating are all

within the Area of Safe Operation (ASO).

15. Thermal Shutdown Circuit(TSD)

This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always

be within the IC’s maximum junction temperature rating. If however the rating is exceeded for a continued period, the

junction temperature (Tj) will rise which will activate the TSD circuit that will turn OFF all output pins. When the Tj falls

below the TSD threshold, the circuits are automatically restored to normal operation.

Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no

circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from

heat damage.

16. Over Current Protection Circuit (OCP)

This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This

protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should

not be used in applications characterized by continuous operation or transitioning of the protection circuit.

17. Disturbance light

In a device where a portion of silicon is exposed to light such as in a WL-CSP, IC characteristics may be affected due

to photoelectric effect. For this reason, it is recommended to come up with countermeasures that will prevent the chip

from being exposed to light.

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Ordering Information

B D 9

4

1

5

F

S

-

E 2

Part Number

Package

F: SSOP-A32

Packaging and forming specification

E2: Embossed tape and reel

Marking Diagrams

SSOP-A32(TOP VIEW)

Part Number Marking

LOT Number

B D 9 4 1 5 F S

1PIN MARK

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Physical Dimension, Tape and Reel Information

Package Name

SSOP-A32

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BD9415FS

Revision History

Date

Revision

001

Change

12 May.2016

New Release

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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

EU

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 depending on ambient temperature. When used in sealed area, confirm that it is the use in

the range that does not exceed the maximum junction 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 on a surface-mount products, the flow soldering method must

be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,

please consult with the ROHM representative in advance.

For details, please refer to ROHM Mounting specification

Notice-PGA-E

Rev.003

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

A two-dimensional barcode 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 concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign

trade act, please consult with ROHM 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.

2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the

Products with other articles such as components, circuits, systems or external equipment (including software).

3. 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 Products or the information contained in this document. Provided, however, that ROHM

will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to

manufacture or sell products containing the Products, subject to the terms and conditions herein.

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-PGA-E

Rev.003


型号：	BD9415FS-GE2
厂家：	ROHM
描述：	LED Driver, 48-Segment, PDSO32, SSOP-32 驱动光电二极管接口集成电路
文件：	总33页 (文件大小：2532K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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