ROHM BD9479FV Datasheet

t

Datashee

LED Drivers for LCD Backlights

White LED Driver for large LCD
Panels (DCDC Converter type)

BD9479FV

●General Description

BD9479FV is a high efficiency driver for white LEDs
and designed for large LCDs. This IC is built-in a boost
DCDC converters that employ an array of LEDs as the
light source. BD9479FV has some protect function
against fault conditions, such as the over-voltage
protection (OVP), the over current limit protection of
DCDC (OCP), the short circuit protection (SCP), the
open detection of LED string. Therefore BD9479FV is
available for the fail-safe design over a wide range
output voltage.

●Key Specification

 Operating power supply voltage range: 9.0V to 35.0V
 Oscillator frequency: 150kHz (RT=100kΩ)
 Operating Current: 8.7mA (typ.)
 Operating temperature range: -40℃ to +85℃

●Applications

TV, Computer Display, Notebook, LCD Backlighting

●Typical Application Circuit

PWMx

STB

PWMx

BSx

7

8

LSP

STB

VREF

CLx

FB

34

33

4

5

6

CS

OVP

CP

UVLO

RT

SS

37

36

35

1

2

3

PGND

REG50

N

AGND

VCC

FAIL

40

39

38

VREF

FAIL

Figure 2. Typical Application Circuit

●Features

 8ch LED constant current driver (external PNP Tr

Type)

 Maximum LED setting current 500mA (VREF pin

setting)

 Build-in DC/DC converter
 Analog Dimming (Linear) function
 Individual channel PWM Dimming function
 LED protection function (Open Short protection)

[PWM-independent Type]

 Output short protection (OVP)
 Built-in Timer latch function (CP)
 Built-in under voltage Lockout function (UVLO)・over

voltage protection (OVP)

 Built-in FAIL indication function
 Built-in OVP voltage Feedback function
 Built-in PWM-independent soft start circuit
 SSOP-B40 Package

●Package W(Typ.) D(Typ.) H(Max.)

SSOP-B40: 13.6mm x 7.80mm x 1.80mm

Pin Pitch: 0.65mm

Figure 1. SSOP-B40

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

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Datasheet

BD9479FV

●Absolute maximum ratings (Ta=25℃)

Parameter Symbol Ratings Unit

Power supply voltage VCC 36 V

BS1-8 terminal voltage BS1-8 40 V

OVP, STB, PWM1-8,VREF,UVLO terminal voltage OVP, STB, PWM1-8,VREF,UVLO 20 V
REG50, N, CS, CP, LSP, CL1-8, FB, SS, RT

terminal voltage
Power dissipation (SSOP-B40)*1 Pd 1.125

Operating temperature range Ta(opr) -40 to +85 ℃

Storage temperature range Tstg -55 to +150 ℃

Junction temperature Tjmax 150 ℃

(Note1) SSOP-B40 package at Ta25C or higher, de-rating power rating by 9.0mW/C(70.0mm x 70.0mm x1.6mm with 1-layer board)

●Operating Ratings (Ta = 25℃)

Above operating condition are the constants of IC itself. Please pay attention at the actual set.

●Recommended external component range

Above operating condition are the constants of IC itself. Please pay attention at the actual set.

●Pin Configuration ●Marking diagram and physical dimension

Parameter Symbol Limits Unit

VCC supply voltage VCC 9.0 to 35.0 V

Analog Dimming setting (VREF Pin) range VREF 0.6 to 3.0 V

LSP setting voltage range VLSP 0.3 to 3.0 V

DC/DC oscillation frequency FCT 100 to 800 kHz

PWM pin input frequency range F_PWM 0.05 to 20 kHz

Parameter Symbol Limits Unit

VCC pin connecting capacity CVCC 1 to 100 uF

DC/DC frequency setting resistant RRT 18.75 to 150 kΩ

REG50 pin connecting capacity CREG50 1.0 to 10 uF

Soft start setting capacity CSS 0.001 to 1.0 uF

Timer Latch setting capacity CCP 0.001 to 1.0 uF

SSOP-B40

REG50, N, CS, CP, LSP, CL1-8,

FB, SS, RT

BD9479FV

1PIN MARK

Figure 4. Physical Dimension

7 V

(Note1)

W

Marking

LOT No

Datasheet

Figure 3. Pin Configuration

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BD9479FV

Datasheet

●Electrical Characteristics (Unless otherwise noted, Ta = 25

Parameter Symbol

[Whole Device]

Operation current ICC

Standby current IST

[UVLO Block]

Operation Voltage （VCC）

Hysteresis Voltage （VCC）

Operation Voltage （UVLO）

Hysteresis Voltage（UVLO）

[DC/DC Block]

Error amp Base Voltage VEAMP 0.55 0.60 0.65 V BSx pin, VREF=0.9V

Oscillation frequency FCT 142.5 150.0 157.5 kHz RT=100kΩ

N pin MAX DUTY output

N pin source ON resistor RNSO 0.5 1 2 Ω

VUVLO_VCC 6.5 7.5 8.5 V VCC=SWEEP UP

VUHYS_VCC 150 300 600 mV VCC=SWEEP DOWN

VUVLO 2.91 3.00 3.09 V UVLO=SWEEP UP

VUHYS 170 210 250 mV UVLO=SWEEP DOWN

NMAX_DUT

Y 90 95 99 % RT=100kΩ

o

C, VCC=24V)

Limit

Min. Typ. Max.

－

－

8.7 14.0 mA STB=3V, PWM1-8=0V

12 24 uA STB=0V

Unit Condition

N pin sink ON resistor RNSI 0.5 1 2 Ω

RT pin Voltage VRT 1.00 1.50 2.00 V RT=100kΩ

SS pin source current ISSSO -2.4 -2.0 -1.6 uA

Soft start ended Voltage VSS_ED 3.6 4.0 4.4 V

FB pin source current IFBSO -110 -100 -90 uA

FB pin sink current IFBSI 85 100 115 uA

Over current detect Vlotage VCS 0.35 0.40 0.45 V

[DC/DC Protection Block]

CP pin source current ICPSO -2.4 -2.0 -1.6 uA

CP pin detect Voltage VCP 2.375 2.500 2.625 V

OVP High detect voltage VOVPH 2.137 2.250 2.363 V

OVP Feedback Voltage VOVPFB 2.375 2.500 2.625 V

OVP Low detect Voltage VOVPL 0.14 0.20 0.30 V

[LED PNP Driver Block]

CL pin current setting Voltage VRCL 295.5 300.0 304.5 mV VREF=0.9V
CL pin current setting Voltage
(Analog MAX) VRCLMAX -3% 1.0 +3% V VREF max=3.0V
CL pin current setting Voltage
(Analog MIN) VRCLMIN -3% 200.0 +3% mV VREF min=0.6V

PNP Driver output sink resistor RBS 55 80 120 Ω PWMx=High, VCL=Low

VREF pin input current IVREF -1.0 0.0 1.0 uA VREF=1V

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Datasheet

●Electrical Characteristics (Unless otherwise noted, Ta = 25oC, VCC=24V)

Parameter Symbol

Min. Typ. Max.

[LED protection Block]

LED OPEN Detect Voltage VOPEN 0.05 0.10 0.15 V BSx=SWEEP DOWN

LED SHORT Detect Voltage VLSP 8.5 9.0 9.5 V

CL pin Detect Voltage VCLLVP 0.05 0.10 0.15 V

LSP pin pull high resistor RULSP 1260 2100 3180 kΩ LSP=0V

LSP pin pull down resistor RDLSP 540 900 1620 kΩ LSP=3V

[REG50 Block]

REG50 output Voltage REG50 4.95 5.00 5.05 V Io=-5mA

REG50 maximum output current |IREG50| 5 - - mA

[STB Block]

STB pin HIGH Voltage STBH 2.0 - VCC V STB=SWEEP UP

Limit

Unit Condition

BSx=SWEEP UP,
LSP=OPEN

※DCDC block consumption
is neglected.

STB pin LOW Voltage STBL -0.3 - 0.8 V STB=SWEEP DOWN

STB pin Pull Down resistor RSTB 0.5 1.0 2.0 MΩ STB=3.0V

[PWM input Block]

PWMx pin High detect voltage PWM_H 2.0 - 18 V PWM=SWEEP UP

PWMx pin Low detect voltage PWM_L -0.3 - 0.8 V PWM=SWEEP DOWN

PWMx pin Pull Down resistor RPWM 0.5 1.0 2.0 MΩ PWM=3.0V

[FAIL Block(OPEN DRAIN)]

FAIL pin Ron RFAIL 30 50 85 Ω
FAIL pin Leakage current

(This product is not designed to be radiation-proof.)

ILFAIL -1.0 0.0 1.0 uA FAIL=36V

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BD9479FV

Datasheet

●Pin Descriptions

Pin No Pin Name In/Out Function Rating [V]

1 REG50 Out 5V regulator output for N output pin -0.3 ~ 7

2 N Out DC/DC switching output pin -0.3 ~ 7

3 PGND - Power GND -

4 CS In DCDC external NMOS current monitor pin -0.3 ~ 7

5 OVP In Overvoltage protection detection pin -0.3 ~ 20

6 CP Out Timer Latch setting pin -0.3 ~ 7

7 LSP In LED short voltage setting pin -0.3 ~ 7

8 STB In Enable pin -0.3 ~ 20

9 BS1 In PNP Tr Base connecting pin１ -0.3 ~ 40
10 BS2 In PNP Tr Base connecting pin２ -0.3 ~ 40
11 BS3 In PNP Tr Base connecting pin３ -0.3 ~ 40
12 BS4 In PNP Tr Base connecting pin４ -0.3 ~ 40

13 BS5 In
14 BS6 In PNP Tr Base connecting pin６ -0.3 ~ 40
15 BS7 In PNP Tr Base connecting pin７ -0.3 ~ 40
16 BS8 In PNP Tr Base connecting pin８ -0.3 ~ 40
17 PWM1 In Dimming signal input pin１ -0.3 ~ 20
18 PWM2 In Dimming signal input pin２ -0.3 ~ 20

19 PWM3 In
20 PWM4 In Dimming signal input pin４ -0.3 ~ 20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

PWM5

PWM6

PWM7

PWM8

CL8

CL7

CL6

CL5

CL4

CL3

CL2

CL1

VREF

FB

SS

RT

UVLO

AGND

FAIL

VCC

In Dimming signal input pin５ -0.3 ~ 20
In Dimming signal input pin６ -0.3 ~ 20
In Dimming signal input pin７ -0.3 ~ 20
In Dimming signal input pin８ -0.3 ~ 20

Out
Out PNP Tr collector ・current detection pin７ -0.3 ~ 7
Out PNP Tr collector ・current detection pin６ -0.3 ~ 7
Out PNP Tr collector ・current detection pin５ -0.3 ~ 7
Out PNP Tr collector ・current detection pin４ -0.3 ~ 7
Out PNP Tr collector ・current detection pin３ -0.3 ~ 7

Out
Out PNP Tr collector ・current detection pin１ -0.3 ~ 7

In LED voltage setting pin -0.3 ~ 20

In/Out DCDC phase-compensation pin -0.3 ~ 7

Out Soft Start pin -0.3 ~ 7

Out DCDC frequency setting resistor connection pin -0.3 ~ 7

In Under voltage Lockout protection pin -0.3 ~ 20

Out Error detection output pin -0.3 ~ 36

PNP Tr Base connecting pin５

Dimming signal input pin３

PNP Tr collector ・current detection pin８

PNP Tr collector ・current detection pin２

- Analog GND -

- Power supply pin -0.3 ~ 36

-0.3 ~ 40

-0.3 ~ 20

-0.3 ~ 7

-0.3 ~ 7

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BD9479FV

Datasheet

●Pin ESD Type

REG50 / N / PGND / CS OVP

CP LSP STB

REG50

N

100k

PGND

CS

BS(1-8) / CL(1-8) PWM(1-8) VREF

FB SS RT

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Figure 5-1. Pin ESD Type

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UVLO FAIL

Figure 5-2. Pin ESD Type

●Block Diagram

Figure 6. Block Diagram

Datasheet

・・・

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●Typical Performance Curve

Figure 7. Operating Current (ICC) [mA] vs. VCC[V]

15

13

11

9

7

ICC [mA]

5

3

9 131721252933

Figure 9. CL1 Voltage (VRCL1) [V] vs. VREF [V]

2

1.6

1.2

0.8

VRCL1 [V]

0.4

0

0.6 1.1 1.6 2.1 2.6

Figure 11. CL1 Voltage (VRCL1) [V] vs. Temp [℃]

400

380

360

340

320

300

280

260

VRCL1 [V]

240

220

200

-40-20 0 20406080

TEMP [°C]

VCC [V]

VREF [V]

Datasheet

Figure 8. REG50[V] vs. VCC[V]

7

6

5

4

REG5 0 [V]

3

2

9 131721252933

VCC [V]

Figure 10. N Frequency [MHz] vs. R_RT [MΩ]

10

1

0.1

N Freq [MHz]

0.01

0.015 0.035 0.055 0.075 0.095 0.115 0.135

RRT [MΩ]

Figure 12. FB Current (IFB) [uA] vs. VBS1 [V]

160

120

80

40

0

-40

IFB [uA ]

-80

-120

-160
0 0.2 0.4 0.6 0.8 1 1.2 1.4

VBS1 [V]

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●Pin Function
○Pin 1: REG50

The REG pin is used in the DC/DC converter driver block to output 5V power. The maximum operating current is 5mA.
Using the REG pin at a current higher than 5mA 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.

○Pin 2: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
approx. 0 to 5V. Frequency setting can be made with a resistor connected to the RT pin. For details of frequency setting,
refer to the description of the ＜RT pin＞.

○Pin 3: PGND

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

○Pin 4: CS

CS pin is current detect 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 overcurrent protection (OCP) function. If the CS pin voltage reaches 0.4V (Typ.) or

more, switching operation will be forcedly stopped.
In order to prevent the malfunction while OCP occurred in BD9479FV,it equipped with mask function.It mask OCP signal

within 200ns interval after N driver is outputted.

 Pin 5: OVP

The OVP pin is an input pin for overvoltage protection and short circuit protection of DC/DC output voltage.When voltage
of it over 2.25V or higher,CP pin start to charge.When it over 2.5V(typ),it will control FB pin.When OVP pin voltage is
near 2.5V,DCDC output feedback will controlled by OVP pin voltage.
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.

 Pin 6: CP

CP pin which sets the time from detection of abnormality until shutdown (Timer latch).It charges constant current
of 2.0uA to capacitor externally connected with CP pin and shuts down when it exceeds 2.5V(Typ.).

 Pin 7: LSP

LED Short detect voltage setting pin.When LSP=OPEN, LSP pin voltage is 0.9V( typ), the BSx pin of LED SHORT detect
voltage is set to 9V.
The 10 times of LSP pin voltage is the BSx pin LED SHORT protection detect voltage.
Please set LSP pin input voltage range from 0.3V～3.0V.

 Pin 8 :STB

ON/OFF setting pin and allowed for use to reset the IC from shutdown.

※The IC state is switched (i.e., The IC 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).

 Pin 9-16 :BS1-BS8

LED DRIVER output pin.Please connect to Base Terminal of external PNP Tr.

 Pin 17-24 :PWM1 – PWM8

ON/OFF terminal of LED driver pin.It inputs PWM dimming signal directly to adjust output DUTY dimming.

High/Low level of PWM terminal is shown as follows:

State PWM Voltage

Datasheet

LED ON state PWM= 2.0V~5.0V

LED OFF state PWM= －0.3V～0.8V

 Pin 25-32 : CL8 – CL1

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