BD83A04EFV-M_技术文档

Datasheet

4 ch Current Driver Integrated, Built-in MOS for Boost, Boost DC/DC Converter

White LED Driver for Automotive

BD83A04EFV-M

General Description

Key Specifications

This IC is a white LED driver for LCD backlight.

It has MOS for boost and 4 ch current drivers for LED drive,

making it ideal for high brightness LED drive. LED pin

maximum voltage is 50 V, making it suitable for driving

medium LCD panels.

The dimming is controlled by the PWM signal and can be

set up to 20,000: 1@100 Hz. It also supports analog

dimming and can accommodate even higher brightness

ranges by combining with PWM dimming. DC/DC

converters can be controlled for boost applications, and the

input operating voltage range is 4.5 V to 48 V.

◼ Input Operating Voltage Range:

◼ Output LED Current Absolute Accuracy:

4.5 V to 48 V

±5.0 %@80.1 mA

Ta = -40 °C to +125 °C

200 kHz to 2420 kHz

-40 °C to +125 °C

120 mA/ ch

◼ DC/DC Oscillation Frequency:

◼ Operating Temperature:

◼ LED Maximum Current:

◼ LED Maximum Dimming Ratio:

◼ LED1 to LED4 Pin Maximum Voltage:

20,000: 1@100 Hz

50 V

Package

HTSSOP-B24

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

7.8 mm x 7.6 mm x 1.0 mm

Features

◼ AEC-Q100 Qualified^{(Note 1)}

◼ Functional Safety Supportive Automotive Products

◼ Built-in 4 ch Current Driver for LED Drive

◼ Built-in MOS for Boost

◼ Current Mode Boost DC/DC Converter

◼ Load Switch (M1) Control Pin

◼ PWM Dimming

(20,000: 1@100 Hz, 100 Hz to 25 kHz)

◼ Spread Spectrum Function

Applications

◼ Automotive CID (Center Information Display) Panel

◼ DC/DC Converter Oscillation Frequency External

Synchronization Function

◼ Navigation

◼ Cluster Panel

◼ LSI Protect Functions (UVLO, OVP, TSD, OCP)

◼ LED Anode/Cathode Short Circuit Protection Function

◼ LED Open/Short Protection Function

(Note 1) Grade 1

◼ HUD (Head Up Display)

◼ Other Small and Medium Sized LCD Panel for

Automotive

Typical Application Circuit

VCC

CVCC

RCSH

VREG

1

2

24

23

22

21

20

19

18

17

16

15

14

13

REG

GND

EN

VCC

CSH

CREG

M1

EN

PWM

3

LDSW

N.C.

D1

CIN

L1

4

PWM

SYNC

RT

D2

VOUT

SYNC

5

SW

RRT

COUT

6

ROVP2

PGND

OVP

CCOMP RCOMP

EXP-PAD

7

COMP

ADIM

ISET

LGND

LED1

LED2

RFAIL

VREG

8

VREG

VFAIL

ROVP1

FAIL

RISET

9

PLSET

N.C.

CPLSET

10

11

12

LED4

LED3

Figure 1. Boost Application Circuit Diagram

〇Product structure : Silicon integrated circuit 〇This product has no designed protection against radioactive rays.

○This product is protected by U.S. Patent No.7,235,954, No.7,541,785 and No.7,944,189.

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Contents

General Description........................................................................................................................................................................1

Features..........................................................................................................................................................................................1

Key Specifications ..........................................................................................................................................................................1

Package..........................................................................................................................................................................................1

Applications ....................................................................................................................................................................................1

Typical Application Circuit ...............................................................................................................................................................1

Contents .........................................................................................................................................................................................2

Pin Configuration ............................................................................................................................................................................3

Pin Descriptions..............................................................................................................................................................................3

Block Diagram ................................................................................................................................................................................5

Description of Blocks ......................................................................................................................................................................6

Absolute Maximum Ratings ..........................................................................................................................................................10

Thermal Resistance......................................................................................................................................................................10

Recommended Operating Conditions...........................................................................................................................................11

Operating Conditions (External Constant Range).........................................................................................................................11

Electrical Characteristics...............................................................................................................................................................12

Typical Performance Curves.........................................................................................................................................................15

Function Descriptions ...................................................................................................................................................................17

PCB Application Circuit Diagram ..................................................................................................................................................28

List of External Components.........................................................................................................................................................29

Application Components Selection Method ..................................................................................................................................31

Precautions for PCB Layout..........................................................................................................................................................37

Power Consumption Calculation Example....................................................................................................................................38

Application Circuit Example ..........................................................................................................................................................40

I/O Equivalence Circuit .................................................................................................................................................................41

Operational Notes.........................................................................................................................................................................42

Ordering Information.....................................................................................................................................................................44

Marking Diagram ..........................................................................................................................................................................44

Physical Dimension and Packing Information...............................................................................................................................45

Revision History............................................................................................................................................................................46

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Pin Configuration

(TOP VIEW)

1

2

24

23

22

21

20

19

18

17

16

15

14

13

REG

GND

EN

VCC

CSH

3

LDSW

N.C.

4

PWM

SYNC

RT

5

SW

6

PGND

OVP

FAIL

EXP-PAD

7

COMP

ADIM

ISET

LGND

LED1

LED2

8

9

PLSET

N.C.

10

11

12

LED4

LED3

Figure 2. Pin Configuration

Pin Descriptions

Signal Type

Pin No. Pin Name

Function

(Note 1)

Internal reference voltage: Used as the reference voltage for the internal circuit. 5 V (Typ) is

generated and output by setting the EN pin to High. Connect a capacitance of 2.2 μF for

phase compensation.

1

REG

A

Small signal ground: Use this for the ground of external components connected to the REG,

RT, COMP, ADIM, ISET, PLSET, OVP, and VCC pins.

2

3

4

GND

EN

A

I

Enable input: The EN pin is turned High to activate the internal circuit. The internal circuit

stops and the standby state is set by setting to Low.

PWM dimming signal: The LED current can be controlled according to On Duty of the

input PWM signal.

PWM

I

External synchronization frequency input / SSCG setting: The internal oscillation

frequency can be externally synchronized by inputting an external clock signal to the SYNC

pin before the Self Diagnosis is completed. When using spread spectrum mode (SSCG),

short the SYNC pin and the REG pin beforehand.

5

6

SYNC

RT

I

Resistor connection for oscillation frequency setting: The oscillation frequency (f_OSC) of

DC/DC converter can be set by connecting a resistor (R_RT) between the RT pin and the GND

pin.

A

Phase compensating capacitor connection: The reference voltage and LED pin voltage

generated by REF Voltage block are compared and output by Error AMP. Connect a filter for

phase compensation.

7

8

COMP

ADIM

A

DC dimming setting: ISET pin voltage can be changed according to the voltage input to the

ADIM pin. When using only PWM dimming, short the ADIM pin with the REG pin.

Resistor connection for LED current setting: LED current (I_LED) can be set by connecting a

resistor (R_ISET) between the ISET pin and the GND pin.

9

ISET

LGND

LED1

A

P

10

11

Large current ground 1: GND of the current driver (the LED1, LED2, LED3, and LED4 pins).

LED cathode connection 1: Open drain output of the current driver ch 1 for LED drive.

Connect to the LED cathode.

LED cathode connection 2: Open drain output of the current driver ch 2 for LED drive.

Connect to the LED cathode.

12

13

14

LED2

LED3

LED4

P

LED cathode connection 3: Open drain output of the current driver ch 3 for LED drive.

Connect to the LED cathode.

LED cathode connection 4: Open drain output of the current driver ch 4 for LED drive.

Connect to the LED cathode.

(Note 1) A: Sensitive signal such as detect and reference, I: Input signal from other units, P: Large current signal susceptible to impedance, including transient

current.

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Pin Descriptions – continued

Signal Type

Pin No. Pin Name

Function

(Note 1)

15

N.C.

Not connected internally.

-

Switching pulse number setting: Pulse addition function is provided to stabilize DC/DC

converter output voltage even when PWM Duty is low. The number of switching pulses to be

added can be set by the capacitance value connected between the PLSET pin and the GND

pin.

16

PLSET

A

Error output flag: Outputs the status of protective operation from the FAIL pin. Since this pin

is an open drain output, use a resistor to pull it up to the REG pin, etc.

17

18

FAIL

OVP

O

A

Overvoltage protection and short circuit protection detection input: When OVP pin

voltage rises to 1.21 V or more, the overvoltage protection (OVP) is activated, and DC/DC

converters are switched OFF. If OVP pin voltage is 0.1 V or less for 3.56 ms, Short Circuit

Protection (SCP) is activated, and both DC/DC converter and the current driver are turned

OFF.

19

20

21

PGND

SW

P

-

Large current ground 2: GND of DC/DC converter. Use it for C_OUTground.

FET drain signal for boost: Switching signal output of DC/DC converter. Connect the SW

pin to the node between the inductor and the rectifier diode.

N.C.

Not connected internally.

Output for driving the load switch gate: The signal output for driving the gate of the load

switch. When the input overcurrent protection is activated, the load switch is turned OFF as

LDSW pin voltage = VCC pin voltage.

22

23

LDSW

CSH

P

A

Input current detection input: The input current is converted to voltage by the input current

detection resistor (R_CSH) connected between the VCC-CSH pin and detected by the CSH pin.

Turns the load switch OFF when the input overcurrent protection is activated.

Power supply voltage input: The input operating voltage range is 4.5 V to 48 V, but when

the IC is started, start it with VCC ≥ 5.5 V. The decoupling capacitor (C_VCC) between the VCC

pin and the GND pin should be as close to the IC pin as possible.

24

-

VCC

P

-

EXP-

PAD

The EXP-PAD should be connected to the board ground.

(Note 1) A: Sensitive signal such as detect and reference, I: Input signal from other units, O: Output signal to other units, P: Large current signal susceptible to

impedance, including transient current.

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Block Diagram

VCC

CSH

LDSW

EN

LDSW

Driver

VREF

PROTECT

REG

PLSET

RT

Low side FET /

Pre Driver

PROTECT

Additional

Pulse

DC/DC

Control

LOGIC

SW

REG

OSC

SLOPE

+

－

SSCG

PWM

COMP

PGND

SYNC

COMP

Error

AMP

－

+

LED1

LED2

LED3

LED4

Soft

Start

LDSW

Driver

Minimum

Channel

Selector

PROTECT

UVLO

DC/DC

Control

LOGIC

ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀFAIL

TSD

SCP

OCPH

ISET SCP

FAIL

OCPL

OVP

OPEN Det

SHORT Det

OVP

Current

Driver

Internal

CLK

REF

Voltage

Dimming

Control

PWM

VCC

ADIM

ISET

CH1 CH2 CH3 CH4

Current Driver

GND

LGND

Figure 3. Internal Block Diagram

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Description of Blocks

Unless otherwise stated, the value in the sentence is the typical value.

1 VREF

Internal reference voltage circuit. By setting the EN pin to High, 5 V is generated and output to the REG pin. REG voltage

is used as the power supply for the internal circuit. Also, this is used to fix each input pin to High voltage outside the IC.

Connect REG capacitance (C_REG= 2.2 μF) to the REG pin for the phase compensation. Note that if C_REGis not connected,

unstable operation such as oscillation will occur.

2 LDSW Driver

Input overcurrent protection circuit. If the voltage between the VCC-CSH pin is 0.1 V or more and continues for 10 μs or

more, the input overcurrent protection is activated, and the load switch (M1) is turned OFF as LDSW pin voltage = VCC

pin voltage. Then, after 3.56 ms elapses, the load switch is turned ON. At this time, if the voltage between the VCC-CSH

pin is 0.1 V or more, the load switch is turned OFF again. If the voltage between the VCC-CSH pin is less than 0.1 V, Self

Diagnosis is performed and restarted. When the input overcurrent protection is detected, the FAIL pin goes Low. The VCC-

LDSW pin is connected by a 3 MΩ resistor inside the IC. Do not connect a resistor between the VCC-LDSW pin because

connecting a resistor between the VCC-LDSW pin outside the IC may prevent the load switch from being turned ON.

When the VCC voltage is turned ON setting the EN pin to Low, the voltage between the VCC-LDSW pins may open

momentarily and an inrush current may flow depending on the VCC startup speed and the type of load switch used. Be

sure to check with the actual application.

3 OSC (Oscillator)

Oscillation frequency generator. The oscillation frequency (f_OSC) of DC/DC converter can be set by connecting a resistor

for oscillation frequency setting (R_RT) between the RT pin and ground. In addition, the oscillation frequency of DC/DC

converter can be externally synchronized by inputting the external synchronization frequency (f_SYNC) to the SYNC pin.

4 SSCG (Spread Spectrum Clock Generator)

Spread spectrum circuit. The spread spectrum function (SSCG) is activated by shorting the SYNC pin and the REG pin.

Noise peaks can be reduced by periodically changing the oscillation frequency by SSCG. The fluctuation range of the

frequency due to SSCG is from 100 % to 92 % of the set oscillation frequency. The oscillation frequency fluctuation period

is 2.3 kHz.

5 SLOPE

This circuit generates a saw wave that serves as the source of the switching pulse of DC/DC converter. SLOPE output

signal and COMP pin voltage are compared, and a switching pulse is generated.

6 Minimum Channel Selector

Selector circuit for detecting LED pin voltages. Selects the lowest pin voltage among LED1 to LED4 pin voltages and inputs

it in Error AMP.

7 Error AMP (Error Amplifier)

This is an error amplifier that takes LED control voltage and the smallest value of the LED1 to LED4 pin voltages as input.

Phase compensation can be set by connecting a resistor and a capacitor to the COMP pin.

8 Soft Start

Soft start circuit for DC/DC converters. This function is used to suppress a steep increase in the inductor current at startup

and an overshoot in the output voltage. Controls the change in switching Duty by limiting the rising edge of the output of

Error AMP (COMP pin voltage) with the soft start function.

9 PWM COMP (PWM Comparator)

This comparator compares COMP pin voltage, which is the output of Error AMP, with SLOPE output signal. Controls the

Duty of the switching pulse of DC/DC converter.

10 Additional Pulse

This circuit adds switching pulses of DC/DC converter. With the pulse addition function, the LED current can be supplied

stably even when the PWM dimming ratio decreases.

11 DC/DC Control LOGIC

This circuit generates the logic of the built-in Low side FET for boost output from the SW pin.

12 Low side FET / Pre Driver

Built-in Low side FET for boost output from the SW pin and its driving circuit.

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Description of Blocks - continued

13 Internal CLK

This circuit generates the internal reference clock. It is a clock of 2.3 MHz and used as a counter.

14 Dimming Control

This circuit controls the dimming rate during PWM dimming.

15 Current Driver / ISET

Current driver circuit for lighting LED. LED current can be set by connecting a resistor to the ISET pin.

16 PROTECT

Outputs the status of protective operation from the FAIL pin. Since this pin is an open drain output, connect it to the REG

pin with a resistor. If the status of protective operation is not monitored, turn the FAIL pin to OPEN or connect to the GND

pin.

16.1 UVLO (Under Voltage Lockout)

Under Voltage Lockout. When VCC pin voltage is 4.10 V or less or REG pin voltage is 3.95 V or less, Under

Voltage Lockout (UVLO) is activated, and the load switch (M1), DC/DC switching, and current driver turn OFF.

When VCC pin voltage is 4.25 V or more and REG pin voltage is 4.10 V or more, UVLO is released and the IC

restarts from Self Diagnosis. When UVLO is detected, output of the FAIL pin does not change. When the FAIL pin

is pulled up to REG, FAIL pin voltage will also drop as REG decreases.

16.2 TSDLED (Thermal Shutdown for Current Driver)

This is a temperature protection circuit that monitors the vicinity of the current driver on the chip. Prevents chip

temperature from rising due to output current fault. When the chip temperature rises to 175 °C or more, the

temperature protection circuit (TSDLED) is activated, the load switch (M1), DC/DC switching, and current driver

are turned OFF. When the chip temperature falls 150 °C or less, TSDLED is released, the IC restarts from Self

Diagnosis. When TSDLED is detected, the output of the FAIL pin does not change.

16.3 TSDREG (Thermal Shutdown for REG)

This is a temperature protection circuit that monitors the vicinity of the REG pin on the chip. Prevents chip

temperature rising due to the REG pin failure. When the chip temperature rises to 175 °C or more, the temperature

protection circuit (TSDREG) is activated, and REG pin voltage, load switch (M1), DC/DC switching, and current

driver turn OFF. When the FAIL pin is pulled up to the REG pin, FAIL pin voltage drops as REG pin voltage is

turned OFF, and it is output to Low. When the FAIL pin is pulled up to an external power supply, the FAIL pin is

output to High. When the chip temperature falls 150 °C or less, TSDREG is released and the IC restarts from Self

Diagnosis.

16.4 OCPL (Over Current Protection for Low side)

When the current flowing through Low side FET (the SW pin) becomes 3.6 A or more, the overcurrent protection

(OCPL) is activated and only DC/DC switching is stopped. If the current is less than 3.6 A, the overcurrent

protection is released, and switching is resumed. When OCPL is detected, output of the FAIL pin does not change.

16.5 OVP (Over Voltage Protection)

Output overvoltage protection circuit. When OVP pin voltage (resistor division of DC/DC converter output voltage)

becomes to 1.21 V or more, the overvoltage protection circuit (OVP) activates and only DC/DC switching is

stopped. When OVP pin voltage falls 1.16 V or less, OVP is released. When OVP is detected, the output of the

FAIL pin goes Low.

16.6 OPEN Det (LED Open Detection)

LED open protection circuit. When any of LED1 to LED4 pin voltages is 0.2 V or less and OVP pin voltage is 1.21

V or more, LED open protection (OPEN Det) is activated, and the current driver is latched OFF only for the LED

row that is open. OPEN Det is released when V_EN= Low or UVLO is detected. When OPEN Det is detected, the

FAIL pin goes Low.

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16 PROTECT – continued

16.7 SHORT Det (LED Short Detection)

LED short protection circuit. When LED pin voltage is 5 V or more for 3.56 ms (counter), LED short protection

(SHORT Det) is activated, and the current driver is latched OFF only for the corresponding LED row. However,

the counter is reset when LED pin voltage does not satisfy the detection condition prior to SHORT Det being

activated. SHORT Det is released when V_EN= Low or UVLO is detected. Since the 3.56 ms counter is counted up

only when PWM = High, the time until SHORT Det is detected varies depending on PWM Duty. When SHORT

Det is detected, the FAIL pin goes Low. SHORT Det can be detected when the PWM pulse width is 20 μs (MIN)

or more.

16.8 SCP (Short Circuit Protection)

Short Circuit Protection circuit. If any of the LED1 to LED4 pin voltages are 0.2 V or less or OVP pin voltage is 0.1

V or less for 3.56 ms (counter), the Short Circuit Protection (SCP) is activated, and the load switch (M1), DC/DC

switching, and current driver turn OFF. However, the counter is reset when each pin voltage does not satisfy the

condition prior to SCP being activated. The SCP is released when V_EN= Low or UVLO is detected. When SCP is

detected, the FAIL pin goes Low. Also, DC/DC converter attempts to output higher voltage because the grounded

LED pin voltage (lowest LED pin voltage) is controlled to be V_LEDCTL. Depending on the power supply voltage and

the load condition, OVP pin voltage may become 1.21 V or more prior to SCP being activated, and LED open

protection may be activated first. In this case, current driver turns OFF only for the grounded LED pin, but the LED

continues to light in a state where the current control is lost because it has been grounded. Even when LED open

protection is detected, the FAIL pin goes Low. Therefore, abnormality can be detected by monitoring this.

16.9 OCPH (Over Current Protection for High side) / LDSW Driver

Input overcurrent protection circuit. If a condition in which the voltage between the VCC-CSH pin is 0.1 V or more

continues for 10 μs or more, the input overcurrent protection (OCPH) is activated. It becomes LDSW pin voltage

= VCC pin voltage and the load switch (M1), DC/DC switching, and current driver turn OFF. Then, after 3.56 ms

(counter) elapses, the load switch is turned ON. At this time, if the voltage between VCC-CSH is 0.1 V or more,

the load switch, DC/DC switching, and current driver are turned OFF again. Also, if the voltage between VCC-

CSH is less than 0.1 V, Self Diagnosis is performed and restarted. When OCPH is detected, the FAIL pin goes

Low. The components on the overcurrent path may generate current again with restart, resulting in heat generation.

Check the calorific value on the actual device.

16.10 ISET Pin Fault (ISET-GND Short Protection)

ISET pin fault protection circuit. When the resistance value connected to the ISET pin falls 3.5 kΩ or less (when

ADIM = REG), ISET pin fault protection is activated, and the load switch (M1), DC/DC switching, and current driver

are turned OFF. If the resistance value connected to the ISET pin is more than 3.5 kΩ (when ADIM = REG), ISET

pin fault protection is released, and the load switch, DC/DC switching, and current driver are turned ON. When

ISET pin fault is detected, the FAIL pin goes Low.

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Description of Blocks – continued

Detect Conditions and Operation at Detection of Each Protection Function (All values in the table are Typ values)

Operation at Detection

Detect Condition

Protection Function

(Block Name)

No.

1

Load

DC/DC

Current

Driver

FAIL

[Detect]

[Release]

Switch Switching

Under Voltage

Lockout

VCC ≤ 4.10 V

or

VCC ≥ 4.25 V

and

High

(Note 5)

OFF

(UVLO)

V_REG≤ 3.95 V

V_REG≥ 4.10 V

Thermal Shutdown

LED

High

(Note 5)

2

3

Tj ≥ 175 °C

Tj ≤ 150 °C

OFF

(TSDLED)

Thermal Shutdown

REG

High

(Note 5)

OFF

(Note 6)

(TSDREG)

Overcurrent

Protection

(OCPL)

High

(Note 5)

4

5

I_SW≥ 3.6 A

I_SW< 3.6 A

ON

OFF

ON

Overvoltage

Protection

(OVP)

V_OVP≥ 1.21 V

V_OVP≤ 1.16 V

Low

Only

detection

LED pin

is OFF

Only

LED Open

Protection

(OPEN Det)

V_LEDn≤ 0.2 V^{(Note 1)}

and

V_EN= Low

or

Latch

Low

6

7

ON

V_OVP≥ 1.21 V

Detects UVLO

LED Short

Protection

V_EN= Low

or

Detects V_LEDn≥ 5.0 V

for 3.56 ms or more^{(Note 2)}

detection

LED pin

is OFF

Latch

Low

(SHORT Det)

Detects UVLO

Detects

V_LEDn≤ 0.2 V

or

Short Circuit

Protection

(SCP)^{(Note 3)}

V_EN= Low

or

Latch

Low

8

9

OFF

V_OVP≤ 0.1 V

Detects UVLO

for 3.56 ms or more

Detects

Input Overcurrent

Protection

(OCPH)^{(Note 3)}

Voltage between the

voltage between the

VCC-CSH pin ≥ 0.1 V

for 10 μs or more

VCC-CSH pin < 0.1 V

OFF

Low

(Note 4)

ISET-GND

ISET resistor

> 3.5 kΩ

ISET resistor ≤ 3.5 kΩ

(when ADIM = REG)

10 Short Protection

(ISET Pin Fault)

(when ADIM = REG)

(Note 1) LEDn indicates one of the LED1 to LED4 pins.

(Note 2) LED pin voltage of at least 1channel shall be less than V_LEDCTL(MIN)x 1.2. When LED pin voltages of all channels are 2.4 V or more, the LED short protection

does not operate. Since the 3.56 ms counter is counted up only when PWM = High, the time until SHORT Det is detected varies depending on PWM Duty.

(Note 3) When Short Circuit Protection (SCP) and Input Overcurrent Protection (OCPH) are detected at the same time, the operation of Input Overcurrent Protection

takes precedence.

(Note 4) When 3.56 ms elapses after the load switch is turned OFF, the load switch turns ON. At this time, when the voltage between VCC-CSH ≥ 0.1 V, the load

switch, DC/DC switching, and current driver are turned OFF again. Also, when the voltage between VCC-CSH < 0.1 V, Self Diagnosis is performed and

restarted.

(Note 5) When pulled up to any voltage, it becomes High output.

(Note 6) REG is also turned OFF during TSDREG, so if pulled up to the REG pin, FAIL pin voltage drops with REG pin voltage.

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Absolute Maximum Ratings (Ta = 25 °C)

Parameter

Symbol

Rating

Unit

V

VCC, LDSW, CSH, SW Pin Voltage

VCC, V_LDSW, V_CSH, V_SW

VCC-V_LDSW, VCC-V_CSH

V_LED1, V_LED2, V_LED3, V_LED4

-0.3 to +50.0

-0.3 to +7.0

-0.3 to +50.0

Voltage Between VCC-LDSW, VCC-CSH Pin

V

LED1, LED2, LED3, LED4 Pin Voltage

V

RT, COMP, ISET, PLSET,

V_RT, V_COMP, V_ISET,

-0.3 to V_REG

V

OVP, ADIM, FAIL Pin Voltage

V_PLSET, V_OVP, V_ADIM, V_FAIL

EN, REG, SYNC, PWM Pin Voltage

Storage Temperature Range

V_EN, V_REG, V_SYNC, V_PWM

-0.3 to +7.0

-55 to +150

150

V

Tstg

°C

Maximum Junction Temperature

Tjmax

°C

Caution 1: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit

between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is

operated over the absolute maximum ratings.

Caution 2: 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, design a PCB with thermal resistance taken into consideration by increasing

board size and copper area so as not to exceed the maximum junction temperature rating.

Thermal Resistance^{(Note 1)}

Thermal Resistance (Typ)

Parameter

Symbol

Unit

1s^{(Note 3)}

2s2p^{(Note 4)}

HTSSOP-B24

Junction to Ambient

Junction to Top Characterization Parameter^{(Note 2)}

θ_JA

90.9

6

30.1

4

°C/W

Ψ_JT

(Note 1) Based on JESD51-2A (Still-Air). The BD83A04EFV-M chip is used.

(Note 2) The thermal characterization parameter to report the difference between junction temperature and the temperature at the top center of the outside

surface of the component package.

(Note 3) Using a PCB board based on JESD51-3.

(Note 4) Using a PCB board based on JESD51-5, 7.

Layer Number of

Measurement Board

Material

FR-4

Board Size

Single

114.3 mm x 76.2 mm x 1.57 mmt

Top

Copper Pattern

Thickness

70 μm

Footprints and Traces

Layer Number of

Measurement Board

Thermal Via^{(Note 5)}

Material

FR-4

Board Size

114.3 mm x 76.2 mm x 1.6 mmt

2 Internal Layers

Pitch

Diameter

4 Layers

1.20 mm

Φ0.30 mm

Top

Copper Pattern

Bottom

Thickness

70 μm

Copper Pattern

Thickness

35 μm

Copper Pattern

Thickness

70 μm

Footprints and Traces

74.2 mm x 74.2 mm

(Note 5) This thermal via connects with the copper pattern of all layers.

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BD83A04EFV-M

Recommended Operating Conditions

Operating Range

Parameter

Symbol

Unit

Min

4.5

Max

48.0

Power Supply Voltage^{(Note 1)}

VCC

f_OSC

V

DC/DC Oscillation Frequency Range

(SSCG = OFF)

200

2420

kHz

PWM Frequency Range^{(Note 2)}

ADIM Input Voltage Range^{(Note 3)}

f_PWM

0.1

0.4

25.0

V_REG

kHz

V

V_ADIM

Higher of

Lower of

External Synchronized Frequency Range^{(Note 4)}

f_SYNC

kHz

200 or f_OSCx 0.9

700 or f_OSCx 1.1

External Synchronized Pulse Duty Range^{(Note 5)}

LED Current Setting Range^{(Note 6)}

Operating Temperature

f_SDUTY

I_LED

40

20

60

%

mA

°C

120

Topr

-40

+125

(Note 1) When IC is started, the voltage must be UVLO release voltage or more. Therefore, consider the power supply drop caused by the parasitic resistor

and start the IC at VCC ≥ 5.5 V.

VCC(MIN) = 4.5 V is the minimum value of VCC that can operate the IC alone. The minimum value of power supply voltage that can be set depends on

the connected LED load and external components.

(Note 2) Generally, flickering of LEDs is easier to see when the dimming frequency is set lower than 100 Hz. Set after confirming with the actual device evaluation.

(Note 3) Even if 1.21 V or more is input to the ADIM pin, it is fixed at 1.21 V inside the IC.

(Note 4) When the external synchronization function is not used, connect the SYNC pin to V_REG(SSCG = ON) or GND (SSCG = OFF).

(Note 5) When using the external synchronization function, switching from the external synchronization state to the internal oscillation frequency is not possible

during stable operation.

(Note 6) The amount of current per channel. Set the LED current so that the maximum junction temperature (Tjmax) is not exceeded.

Operating Conditions (External Constant Range)

Operating Range

Parameter

Symbol

Unit

Min

1.0

Typ

Max

4.7

53

REG Capacitance

C_REG

R_ISET

R_RT

2.2

μF

kΩ

nF

μF

LED Current Setting Resistor

Oscillation Frequency Setting Resistor

PLSET Capacitance

11

-

4.6

51.0

10

C_PLSET

C_VCC

-

Input Capacitance 1

1^{(Note 7)}

10^{(Note 7)}

20^{(Note 7)}

-

(Note 8)

Input Capacitance 2

C_INVCC

-

Output Capacitance

C_OUT

100

(Note 7) Set the capacitance so that it does not fall below the minimum value in consideration of temperature characteristics, DC bias characteristics, etc.

(Note 8) C_INVCCmeans the total capacitance of C_INand C_VCC

.

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BD83A04EFV-M

Electrical Characteristics

(Unless otherwise specified, VCC = 12 V, Ta = -40 °C to +125 °C)

Standard Value

Unit

mA

Conditions

Parameter

Symbol

Min

Typ

Max

10

V_EN= 5 V, V_SYNC= 0 V,

V_PWM= 0 V, C_IN= 10 μF,

RT = OPEN, ISET = OPEN,

Circuit Current

I_CC

-

V_ADIM= V_REG

,

Resistance between

LEDn-GND = 10 kΩ

Standby Current

[VREF]

I_ST

-

0

10

μA

V

V_EN= Low

Reference Voltage

[DC/DC Converter]

SW Pin ON Resistor

V_REG

4.7

5.0

5.3

I_REG= -5 mA, C_REG= 2.2 μF

R_{ON_SW}

V_LEDCTL

-

0.2

0.4

Ω

V

I_SW= 50 mA

R_ISET= 15.1 kΩ,

V_ADIM= V_REG

R_ISET= 15.1 kΩ,

V_COMP= 1.0 V,

V_LED= 1.5 V,

V_ADIM= V_REG

R_ISET= 15.1 kΩ,

V_COMP= 1.0 V,

V_LED= 0 V,

LED Control Voltage

0.66

0.76

0.86

COMP Sink Current

I_COMPSINK

150

220

290

μA

COMP Source Current

I_COMPSOURCE

-290

-220

-150

V_ADIM= V_REG

Oscillation Frequency 1

Max Duty 1

f_OSC1

D_{UTY_MAX1}

f_OSC2

306

95

340

-

374

-

kHz

%

R_RT= 33.3 kΩ

R_RT= 4.6 kΩ

V_PLSET= 0 V

Oscillation Frequency 2

PLSET Charge Current

PLSET Set Voltage

1980

35

2200

50

2420

65

kHz

μA

V

I_PLSET

V_PLSET

0.4

0.5

0.6

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BD83A04EFV-M

Electrical Characteristics – continued

(Unless otherwise specified, VCC = 12 V, Ta = -40 °C to +125 °C)

Standard Value

Parameter

[Current Driver]

Symbol

Unit

Conditions

Min

Typ

Max

R_ISET= 15.1 kΩ,

mA

%

LED Current Absolute Variation

I_LEDn

76.1

0

80.1

-

84.1

5

V_ADIM= V_REG

R_ISET= 15.1 kΩ,

V_ADIM= V_REG

LED Current Relative Variation

(Note 1)

I_LEDREL

ISET-GND Short Protection

Resistor

R_ISETLIM

I_ADIM

-

3.5

0

-

+1.0

-

kΩ

μA

μs

V_ADIM= V_REG

V_ADIM= 5 V

ADIM Pin Input Current

-1.0

0.5

PWM Dimming Minimum Pulse

Width

f_PWM= 100 Hz to 25 kHz,

I_LED= 80.1 mA

t_PWMMIN

-

PWM Dimming Frequency

PWM Low Section Detect Time

[Logic Input (EN)]

Input High Voltage

f_PWM

0.1

-

25.0

35.6

kHz

ms

t_PWML

21.4

28.5

V_INH1

V_INL1

R_IN1

2.1

-

V

Input Low Voltage

0.5

150

Input Resistor

50

100

kΩ

V_EN= 5 V

[Logic Input (PWM, SYNC)]

Input High Voltage

V_INH2

V_INL2

R_IN2

2.1

-

V

Input Low Voltage

0.5

150

Input Resistor

50

100

kΩ

V_PWM= V_SYNC= 5 V

(Note 1) I_LEDREL= (I_LEDn(MAX)– I_LEDn(MIN)) / I_LEDn(Ave)x 100

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BD83A04EFV-M

Electrical Characteristics – continued

(Unless otherwise specified, VCC = 12 V, Ta = -40 °C to +125 °C)

Standard Value

Parameter

[PROTECT]

Symbol

Unit

Conditions

Min

Typ

Max

VCCUVLO Detect Voltage

VCCUVLO Release Voltage

REGUVLO Detect Voltage

REGUVLO Release Voltage

OVP Detect Voltage

V_UVLOVCC1

V_UVLOVCC2

V_UVLOREG1

V_UVLOREG2

V_OVPDET

3.90

4.05

3.75

3.90

1.16

4.10

4.25

3.95

4.10

1.21

4.30

4.45

4.15

4.30

1.26

V

VCC = Sweep down

VCC = Sweep up

V_REG= Sweep down

V_REG= Sweep up

V_OVP= Sweep up

OVP Detect Voltage

Hysteresis Width

V_OVPHYS

V_OCPH

V_LDSW

I_OCPL

-

50

100

5.4

-

mV

V

V_OVP= Sweep down

Input OCP Detect Voltage

80

120

6.4

VCC-V_CSH= Sweep up

V_CSH= VCC

VCC-V_LDSW

LDSW Operation Voltage

at Input OCP Release

4.4

3.14

0.1

0.05

0.1

OCPL Detect Current

3.60

0.2

4.06

0.3

A

LED Open Protection Detect

Voltage

V_LED= Sweep down

V_OVP≥ V_OVPDET

V_OPEN

V_SCP1

V_SCP2

V

LED Anode SCP Detect Voltage

0.10

0.2

0.15

0.3

V

V_OVP= Sweep down

V_LED= Sweep down

LED Cathode SCP Detect

Voltage

V

LED Anode SCP Detect

Delay Time

t_SCP1

t_SCP2

2.67

4.7

3.56

5.0

4.45

5.3

ms

V

LED Cathode SCP Detect

Delay Time

LED Short Protection Detect

Voltage

V_SHORT

V_LED= Sweep up

Initial Check Time

t_INICK

R_FAIL

5.34

-

7.12

1.0

8.90

2.0

ms

kΩ

FAIL Pin ON Resistor

I_FAIL= 1 mA

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BD83A04EFV-M

Typical Performance Curves

(Reference data, unless otherwise specified VCC = 12 V)

10

8

5.3

5.2

5.1

5.0

4.9

4.8

4.7

6

4

2

0

4

15

26

37

48

-40 -20

0

20 40 60 80 100 120

Power Supply Voltage : VCC [V]

Temperature : Ta [°C]

Figure 4. Circuit Current vs Power Supply Voltage

Figure 5. Reference Voltage vs Temperature

380

370

360

350

340

330

320

310

300

2.42

2.31

2.20

2.09

1.98

-40 -20

0

20 40 60 80 100 120

-40 -20

0

20 40 60 80 100 120

Temperature : Ta [°C]

Figure 6. Oscillation Frequency 1 vs Temperature

(R_RT= 33.3 kΩ)

Figure 7. Oscillation Frequency 2 vs Temperature

(R_RT= 4.6 kΩ)

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BD83A04EFV-M

Typical Performance Curves – continued

(Reference Data)

84

83

82

81

80

79

78

77

76

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

-40 -20

0

20 40 60 80 100 120

20

40

60

80

100

120

Temperature : Ta [°C]

LED Current : I_LED[mA/ch]

Figure 8. LED Control Voltage vs LED Current

Figure 9. LED Current vs Temperature

100

90

80

70

60

50

100

90

80

70

60

50

8

10

12

14

16

8

10

12

14

16

Power Supply Voltage : VCC [V]

Figure 10. Efficiency 1 vs Power Supply Voltage

(R_RT= 33.3 kΩ, R_ISET= 15.1 kΩ,

Figure 11. Efficiency 2 vs Power Supply Voltage

(R_RT= 4.6 kΩ, R_ISET= 15.1 kΩ,

Number of LED Series = 10, Number of LED Parallels = 4)

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BD83A04EFV-M

Function Descriptions

Unless otherwise stated, the value in the sentence is the Typ value.

1 Current Driver

This model has a built-in 4 ch current driver. The LED current setting range per channel is 20 mA to 120 mA, and the LED

current can be adjusted by the resistance value between the ISET pin and GND.

1.1 How to Set LED Current

1.4 PWM Low Section Detect Function

1.2 When Using Analog Dimming

1.3 When Using PWM Dimming

1.5 LED Pin Handling of Unused Channels

1.6 When Setting the LED Current Above 120 mA

1.1 How to Set LED Current

The LED current I_LEDcan be calculated using the following equation.

푉

퐼_퐿퐸퐷

=

^ꢀ푆ꢁ푇× 10⁶

[mA]

Resistance Value Setting Example (V_ADIM= V_REG

)

푅

ꢀ푆ꢁ푇

ISET Resistor [kΩ]

LED Current [mA]

퐼_퐿퐸퐷: Output current per channel (LED current)

(Recommended operating condition:

20 mA to 120 mA)

53

30

22.8

40.3

80.1

110.0

ꢂ_ꢃꢄ퐸ꢅ: ISET pin voltage 1.21 V

15.1

11

(When ADIM pin voltage V_ADIM= V_REG

ꢆ_ꢃꢄ퐸ꢅ: LED current setting resistor

)

(Recommended operating condition:

When R_ISET≤ 3.5 kΩ, ISET pin short protection detect is

activated and, output of the LED current is stopped.

11 kΩ to 53 kΩ)

120

110

100

90

80

70

60

50

40

30

20

11

16

21

26

31

36

41

46

51

ISET Resistor : R_ISET[kΩ]

Figure 12. I_LEDvs R_ISET(V_ADIM= V_REG

)

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BD83A04EFV-M

1 Current Driver – continued

1.2 When Using Analog Dimming

ISET pin voltage can be adjusted according to the voltage input to the ADIM pin. The LED current I_LEDcan be calculated

from the following equation as described above.

퐼_퐿퐸퐷: Output current per channel (LED current)

(Recommended operating condition:

20 mA to 120 mA)

푉

푅

퐼_퐿퐸퐷

=

^ꢀ푆ꢁ푇× 10⁶

[mA]

ꢀ푆ꢁ푇

ꢂ

_ꢃꢄ퐸ꢅ: ISET pin voltage 1.21 V

However, V_ISETcan be adjusted according to ADIM pin

voltage V_ADIMas follows:

(ADIM pin voltage V_ADIM= V_REG

)

ꢆ_ꢃꢄ퐸ꢅ: LED current setting resistor

(Recommended operating conditions:

11 kΩ to 53 kΩ)

ꢂ

ꢃꢄ퐸ꢅ

= 1.21 [V] (1.21 V ≤ V_ADIM≤ V_REG)

ꢂ

_퐴퐷ꢃ푀: ADIM pin Input voltage

(Recommended operating conditions:

0.40 V to V_REG

ꢂ

ꢃꢄ퐸ꢅ

= ꢂ

[V] (0.40 V < V_ADIM< 1.21 V)

퐴퐷ꢃ푀

)

Note that I_LEDset by R_ISETand V_ADIMcan’t be set to less than 20 mA.

100

90

80

70

60

50

40

30

20

10

0

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

V_ADIM[V]

Figure 13. I_LEDvs V_ADIM(R_ISET= 15.1 kΩ)

1.3 When Using PWM Dimming

The LED current can be controlled according to On Duty of the PWM signal input to the PWM pin. However, in the region

where the ON time of the LED current is less than 0.5 μs or the OFF time is less than 0.5 μs, the pulse time is shorter than

PWM dimming minimum pulse width, so it cannot be used regularly. It is okay to use this region transiently, so it is also

possible to set PWM Duty = 0 % and 100 %.

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BD83A04EFV-M

1 Current Driver – continued

1.4 PWM Low Section Detect Function

Counting starts when PWM = High is switched to Low in the V_EN= High state. When PWM Low section reaches 28.5 ms,

the operation is regarded as OFF state. After that, when PWM input is turned High, switching operation (pre-boost) is

restarted.

1.5 LED Pin Handling of Unused Channels

VOUT

This model has four built-in constant current circuits.

The current can be supplied to the LED by setting the

PWM pin to High, and the LED current can be set by

inserting a resistor between the ISET pin and GND. The

LED current that can be supplied per row is 20 mA to

120 mA.

Pull down the LED pin of the unused channel to GND

with 10 kΩ.

10 kΩ

LED4

LED3

LED2

LED1

Figure 14. When Setting LED4 Unused

1.6 When Setting the LED Current Above 120 mA

The LED1 to LED4 pins can be used in bundles.

For example, as shown in the figure on the right, if

LED1, LED2, LED3, and LED4 are shorted, 4 times the

current set by the ISET pin can be passed.

VOUT

When using only 2 channels in a bundle, mount a

resistor for each LED pin for unused channels (2

channels).

When connected to multiple LED pins with a resistor,

the voltage may deviate from the set value and may not

be recognized as an unused channel. In this case, the

unintentional protection function may be activated, so

perform the LED pin handling correctly.

LED4

LED3

LED2

LED1

Figure 15. Application Example When LED Pins are Shorted

VOUT

10 kΩ

LED4

10 kΩ

LED3

LED2

LED1

LED3

LED2

LED1

Figure 16. Correct LED Pin Handling When Multiple

Channels are Unused

Figure 17. Wrong LED Pin Handling When Multiple

Channels are Unused

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BD83A04EFV-M

Functional Descriptions – continued

Unless otherwise stated, the value in the sentence is the Typ value.

2 DC/DC Converter

Detects the lowest voltage among LED1 to LED4 pin voltages (LED cathode voltages) in Minimum Channel Selector block

and inputs it to Error AMP. The reference voltage of Error AMP is generated in REF Voltage block based on R_ISETresistance

value, which becomes LED pin control voltage. The output of Error AMP is compared with the output of SLOPE block by

PWM COMP block, and a switching signal is output to the SW pin through DC/DC Control LOGIC.

2.1 LED Pin Control Voltage V_LEDCTL

2.5 DC/DC Converter Oscillation Frequency f_OSC

2.6 Pulse Addition Function

2.7 External Synchronization / Spread Spectrum

Function (SSCG)

2.2 VCC Input Voltage and Number of LED Series

2.3 LED Variation and Series Number

2.4 Overvoltage Protection Function OVP

2.8 LSDET Function

2.1 LED Control Voltage V_LEDCTL

DC/DC converter operates so that the lowest voltage among LED1 to LED4 pin voltages (LED cathode voltages) is equal

to the LED control voltage (V_LEDCTL). Power dissipation can be minimized by optimizing the LED control voltage (V_LEDCTL

)

according to the LED current (I_LED).

LED Control Voltage Reference Value (ADIM = REG)

1.2

1.1

LED Control

ISET Resistor

R_ISET[kΩ]

LED Current

I_LED[mA]

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Voltage

V_LEDCTL[V]

53

30

22.8

40.3

80.1

110.0

0.42

0.52

0.76

0.93

15.1

11

20

40

60

80

100

120

LED Current : I_LED[mA/ch]

Figure 18. V_LEDCTLvs I_LED

2.2 VCC Input Voltage and Number of LED Series

To drive the boost DC/DC converter, the LED must be selected so that the output voltage (VOUT) is higher than the input

voltage (VCC).

ꢂ퐶퐶

: Input voltage

ꢂ퐶퐶₍

< ꢂ푂푈ꢇ

< ꢂ푓

)

푀퐴푋

(푀ꢃ푁)

ꢂ푂푈ꢇ : DC/DC converter output voltage

ꢈ

: Number of LED series

: LED Vf voltage

: LED control voltage

× ꢈ + ꢂ

(푀ꢃ푁)

퐿퐸퐷ꢉꢅ퐿 (푀ꢃ푁)

ꢂ푓

ꢂ

퐿퐸퐷ꢉꢅ퐿

Select the number of LED series and Vf characteristics that satisfy

the above equation.

2.3 LED Variation and Series Number

When operating multiple LED outputs, the LED anode voltages in each row are commonly connected to DC/DC converter

output VOUT. LED pin voltage (LED cathode voltage) in the row where the Vf voltage of the LED is the highest is the lowest,

and this is controlled to be V_LEDCTL. Therefore, the voltage of other LED pin outputs will be higher by the amount of Vf

variation. Select the number of LED series and Vf characteristics so that the LED short protection (V_LEDn≥ 5.0 V) does not

operate.

ꢈ × ꢊꢂ푓

₎− ꢂ푓

₎ꢋ < ꢂ

₎− ꢂ

(

푀퐴푋

푀ꢃ푁

ꢄ퐻ꢌ푅ꢅ 푀ꢃ푁 퐿퐸퐷ꢉꢅ퐿 (푀퐴푋)

ꢂ

ꢄ퐻ꢌ푅ꢅ

: LED short protection voltage

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BD83A04EFV-M

2 DC/DC Converter – continued

VOUT

2.4 Overvoltage Protection Function OVP

Inputs the resistor division of the output voltage VOUT

in the OVP pin. When OVP pin voltage rises the

overvoltage protection detect voltage V_OVP(1.21 V) or

more, the overvoltage protection is activated, and the

switching of DC/DC converter is turned OFF. After that

when OVP pin voltage drops to 1.16 V, OVP is released.

R_OVP2

OVP

+

ꢀ

R_OVP1

1.21 V /

1.16 V

Figure 19. OVP Pin Voltage Setting Sample

{(

)

}

ꢂ푂푈ꢇ_ꢌ푉푃= ꢆ_ꢌ푉푃ꢍ+ ꢆ_ꢌ푉푃ꢎ∕ ꢆ_ꢌ푉푃ꢍ× ꢂ_ꢌ푉푃[V]

ꢂ푂푈ꢇ_ꢌ푉푃: DC/DC converter output voltage (VOUT) during overvoltage protection operation

ꢂ_ꢌ푉푃: Overvoltage protection detect voltage

2.5 DC/DC Converter Oscillator Frequency f_OSC

The oscillation frequency (f_OSC) of DC/DC converter can be set by connecting R_RTbetween the RT pin and GND. The

oscillator frequency of DC/DC converter is generated in the OSC block. Set the resistor of R_RTreferring to the data and

theoretical formula below.

7

푓

: Oscillation frequency of DC/DC converter

ꢌꢄꢉ

(

)

푓

ꢌꢄꢉ

= 1.132 × 10 ∕ ꢆ_푅ꢅ× 훼 [kHz]

1.132 × 10⁷: Constants determined inside the circuit

ꢆ_푅ꢅ

훼

: RT pin connecting resistor

: Correction factor

α is the correction factor. For the relation between f_OSCand R_RTincluding the correction factor, refer to f_OSCvs R_RTbelow.

Note that operation cannot be guaranteed if f_OSCsetting value exceeds the recommended range of 200 kHz to 2420 kHz.

Determine f_OSCsetting value in consideration of the variation in electrical characteristics, variation in R_RT, and ON/OFF of

spread spectrum

f_OSCvs R_RT

2400

Example of Resistance Value for f_OSCSetting

2200

2000

R_RT[kΩ]

51

α

1800

1600

1400

1200

1000

800

1.013

1.000

0.980

0.947

0.894

33.3

20

10

600

400

4.6

200

4

6

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

R_RT[kΩ]

Figure 20. f_OSCvs R_RT

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2 DC/DC Converter – continued

2.6 Pulse Addition Function

A pulse addition function is provided to output a stable DC/DC converter output voltage and LED current even when PWM

Duty is low. The output voltage can be held by outputting additional switching of several pulses after the falling edge of the

PWM input signal, and the LED can be turned on normally. When the pulse addition function is not used, set the PLSET

pin to OPEN

V_PWM

0.5 V

V_PLSET

Additional

Pulse Time

t_PLSET

V_SW

VOUT

VOUT Hold

Stable LED Current

I_LED

Figure 21. Pulse Addition Function

The number of additional switching pulses is set in the capacitance value C_PLSETconnected to the PLSET pin. The additional

pulse time t_PLSETis calculated as follows:

푡_{푃퐿ꢄ퐸ꢅ}= 10^ꢍꢏ× 퐶_{푃퐿ꢄ퐸ꢅ}[µs]

푡_{푃퐿ꢄ퐸ꢅ}

퐶_{푃퐿ꢄ퐸ꢅ}

: Additional pulse time

: PLSET pin capacitance

1000

100

10

1

0

0.1

1.0

10.0

PLSET Pin Capacity : C_PLSET[nF]

Figure 22. t_PLSETvs C_PLSET

The additional pulse time required to hold the output voltage VOUT varies depending on various factors such as PWM

frequency, output voltage, output capacitance, LED current, as well as the minimum value of PWM Duty used for dimming.

Contact your sales representative when you request design verification of the required additional pulse time for your usage

conditions.

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2 DC/DC Converter – continued

2.7 External Synchronization /Spread Spectrum Function (SSCG)

Three switching modes can be selected

according to the voltage input to the

SYNC pin.

Mode

1

V_SYNC

Low

DC/DC Switching Frequency

Fixed Frequency Mode Determined by R_RT

Spread Spectrum Mode of the Frequency

Determined by R_RT

2

3

High (= V_REG

Pulse Input

)

Mode to Synchronize with the Frequency Input to

the SYNC Pin

Mode 1:

When the SYNC pin is fixed Low, DC/DC converter switches at a fixed frequency determined by R_RT

.

Mode 2:

By shorting the SYNC pin and the REG pin, operation in spread spectrum mode (SSCG) is enabled. With SSCG, noise

peaks can be reduced by periodically changing the oscillation frequency. The fluctuation range (Δf) of the frequency due to

SSCG is -8 % of the set oscillation frequency from the set oscillation frequency. The oscillation frequency fluctuation period

(t_SSCG) is 1/(2.3 kHz).

VCC

Δｆ = f_OSCx 0.08

V_EN

V_SYNC

V_PWM

Noise

reduction

1.21 V

Pre-boost

Self Diagnosis

V_OVP

V_SW

Δf = -8 %

f_OSC

t_SSCG= 1/(2.3 kHz)

f_OSCx 0.92

f_OSCFrequency

Band

Figure 23. Spread Spectrum Function Timing Chart

Figure 24. Spread Spectrum Function

훥푓

푓

ꢌꢄꢉ

: Fluctuation range of the oscillation frequency by SSCG

: DC/DC oscillation frequency

훥푓 = 푓 × 0.08

ꢌꢄꢉ

푡_ꢄꢄꢉ퐺: The oscillation frequency fluctuation period by SSCG

푡_ꢄꢄꢉ퐺= 1/(2.3 푘ꢐ푧)

When not using SSCG function, short the SYNC pin and the GND pin.

SSCG function cannot be turned ON/OFF during operation.

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2.7 External Synchronization / Spread Spectrum Function (SSCG) – continued

Mode 3:

By inputting an external clock signal to the SYNC pin, the internal oscillation frequency can be externally synchronized.

However, note the following points.

·Since Mode is judged during Self Diagnosis (Initial Check), input the clock signal to the SYNC pin prior to turning the EN

pin to High.

·After the clock signal is input to the SYNC pin and the EN pin is turned High, it is not possible to switch between internal

oscillation and external synchronization. Operation may become unstable. Similarly, after turning the EN pin to High, the

frequency of external synchronization cannot be switched.

·When using the external synchronization function, connect an RC filter with a cutoff frequency equivalent to the input

external synchronization frequency to the SYNC terminal as a countermeasure against interference with the RT terminal.

Be sure to check whether the output voltage of the RC filter satisfies the input threshold of the SYNC pin.

·When using external synchronization, SSCG cannot be used.

·For the external synchronization frequency, input a frequency within ±10 % of the theoretical value of the oscillation

frequency f_OSCset by the RT pin.

Internal SYNC

4.0 V

1.0 V

V_EN

V_REG

V_SYNC

REG

MODE

Selector

SYNC

SSCG: ON, SYNC: OFF

4.0 V

1.0 V

Internal

V_SYNC

SSCG: OFF, SYNC: ON

SSCG: OFF, SYNC: OFF

7.12 ms

SSCG block

To OSC

Initial Check

Figure 25. Synchronous Signal (V_SYNC) Input and

Mode Check (Initial Check) Timing

Figure 26. SYNC Pin Equivalence Circuit

LSDET

OFF

LSDET

ON

LSDET

OFF

2.8 LSDET Function

When the lowest LED pin voltage among LED pins is 2.4 V

or more, DC/DC converter is turned OFF, and COMP voltage

is held. DC/DC converter resumes switching when the lowest

LED pin voltage is less than V_LEDCTLx 1.2.

V_PWM

LSDET function is intended to reduce the voltage quickly

when the output is over boosted. It also prevents the LEDs

from flickering by resuming the switching of DC/DC converter

just before returning to normal operation.

ꢇ

V_SW

ꢄ

①

②

The LED4 pin becomes open and LED4 pin voltage

V_COMP

becomes 0.2 V or less (Ⓐ).

DC/DC converter output begins boosting further to raise

LED4 pin voltage. In conjunction with this, OVP pin

ꢁ

1.21 V

ꢅ

ꢂ

V_OVP

voltage also rises (Ⓑ).

When OVP pin voltage reaches 1.21 V (Ⓒ) due to the

boost of DC/DC converter, the LED open protection is

activated.

When the LED open protection is activated, the LED4

pin that was open is pulled up to REG pin voltage V_REG

V_LED1to

V_LED3

ꢆ

V_LEDCTL

V_LEDCTLx 1.2

inside the IC (Ⓓ).

REG Pull Up (V_REG

)

LSDET function operates because LED4 pin voltage,

which is the lowest LED pin voltage in the LED pins, is

ꢃ

V_LED4

V_LEDCTL

2.4 V

0.2 V

2.4 V or more (Ⓓ).

ꢀ

LSDET function turns OFF DC/DC converters and holds

LED4

Open

LED4

Open

Detection

COMP voltage (Ⓔ).

③

④

DC/DC converter turns OFF, the output voltage drops,

and OVP pin voltage also drops (Ⓕ).

I_LED1

to

I_LED3

When the lowest LED pin voltage is less than V_LEDCTL

x

I_LED4

1.2 (Ⓖ), DC/DC converter resumes switching (Ⓗ).

Figure 27. LSDET Function When LEDs are Open

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Functional Descriptions – continued

Unless otherwise stated, the value in the sentence is the Typ value.

3 Starting Sequence and Effective Section of Each Protection Function

The timing chart at startup and the effective section of each protection function are shown in the figure below.

①

②

Power ON

Self Diagnosis

(Initial check)

: Input EN voltage after the VCC voltage is input.

: After inputting EN voltage, this IC becomes the Self Diagnosis status, determines the channel to

be used, and sets the external synchronization / spread spectrum function, etc. Self Diagnosis is

completed after 7.12 ms, and the diagnostic status is latched.

③

④

Pre-boost

: After Self Diagnosis, pre-boost starts at V_PWM= High, and after 7.12 ms, pre-boost is completed.

Stable operation : The LED current flows according to On Duty of the PWM signal input to the PWM pin. The output

transition section voltage of DC/DC converter with switching turned OFF drops according to the load current.

⑤

Stable state

: When LED voltage (the lowest voltage in LED1 to LED4) drops to LED control voltage x 1.2, DC/DC

converter switches again.

VCC

V_EN

V_REG

V_PWM

4.1 V

(UVLO Release)

ꢌ

ꢈ Self Diagnosis

After Self Diagnosis,

pre-boost starts with V_PWM= High

7.12 ms

・Determination of CH to use

・Setting external

synchronization

ꢋ Stable Operation

ꢉ Pre-boost

ꢊ Stable State

7.12 ms

Transition Section

・Setting spread spectrum

・OVP pin fault detection

・ISET pin fault detection

1.21 V

V_OVP

V_SW

I_LED

LED Setting Current Output Section

LED Control Voltage × 1.2

V_LED

LED Control Voltage

During Self Diagnosis

FAIL is Low

V_FAIL

DC/DC Converter Operating Section

Current Driver Operating Section

Under Voltage Lockout (UVLO) Effective when EN = High

Thermal Shutdown REG (TSDREG) Effective when EN = High

Thermal Shutdown LED (TSDLED) Effective when EN = High

Overcurrent Protection (OCPL) Effective when UVLO is released

Overvoltage Protection (OVP) Effective when UVLO is released

Overvoltage Protection (OVP) / FAIL Flag Effective when LSDET is OFF

Input Overcurrent Protection (OCPH) / FAIL Flag Effective when UVLO is released

ISET-GND Short Protection / FAIL Flag Effective when Self Diagnosis is completed

LED Open Protection / FAIL Flag Effective when pre-boost is completed

LED Short Protection / FAIL Flag Effective when pre-boost is completed

Short Circuit Protection (SCP) / FAIL Flag Effective when pre-boost is completed

Figure 28. Timing Chart at Startup and Effective Section of Each Protection Function

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3 Starting Sequence and Effective Section of Each Protection Function – continued

Unless otherwise stated, the value in the sentence is the Typ value.

3.1 Self Diagnosis (Initial Check)

The contents of Self Diagnosis are as follows.

3.1.1 LED Pin Used/Unused Check

It is possible to check whether the LED pin is used or not by LED pin voltage at the end of Self Diagnosis. If LED pin

voltage is 0.2 V or more and 2.0 V or less during Self Diagnosis, the LED pin is diagnosed as unused. If it is diagnosed

as unused, the LED pin does not operate and is pulled up to REG pin voltage V_REGinside the IC. To select unused

channels correctly, the capacitance value to be connected to the LED pin should be 470 pF or less.

3.1.2 SYNC Pin Setting Check

ON/OFF of the external synchronization or spread spectrum function can be set by SYNC pin voltage at the end of Self

Diagnosis.

3.1.3 FAIL Pin Connection Check

During Self Diagnosis, the FAIL pin can check the connection between the monitor pin of MCU and the FAIL pin by

turning ON the open drain output (ON resistor = 1 kΩ). Determine the pull up voltage and pull up resistor according to

FAIL detection voltage on the MCU. Also, be careful of startup failure when starting by pulling up to the external power

supply, not REG pin voltage. The pull up resistor must satisfy the following conditions.

Example of

External Power Supply

REG Pin

Voltage

Pull Up Voltage (V)

5.0

20

3.3

10

5.0

10

Minimum Value of Pull Up Resistor (kΩ)

3.1.4 ISET-GND Short Check

In Self Diagnosis, ISET-GND Short Check is done under the same conditions as ISET pin fault (ISET-GND short

protection). When ISET-GND short is confirmed, the load switch, DC/DC switching, and current driver are latched OFF.

It is reset when V_EN= Low or UVLO is detected.

3.1.5 OVP Pin Setting Check

Self Diagnosis checks OVP pin setting. The OVP pin during Self Diagnosis is pulled down with IC built-in resistor of 1

MΩ. When an open failure of the OVP pin occurs, OVP pin voltage falls to 0.1 V or less, and the load switch, DC/DC

switching, and the current driver latch OFF. It is reset when V_EN= Low or UVLO is detected.

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Functional Descriptions – continued

4 Stopping Sequence and Effective Section of Each Protection Function

The figure below shows the timing chart when stopping and the effective section of each protection function.

⑤

Stable state

: When LED voltage (the lowest voltage in LED1 to LED4) drops to the LED control voltage x 1.2,

DC/DC converter is switched again.

⑥

Standby state : Decrease EN voltage prior to the VCC voltage falling. Internal circuit is stopped by falling EN

voltage, and IC is in standby state.

VCC

V_EN

REG output

function is OFF

when EN = Low

V_REG

V_PWM

⑥ Standby State

⑤ Stable State

V_OVP

V_OUTL

I_LED

DCDC converter operation is OFF

when EN = Low

Current driver operation is OFF