BD82A26MUF-M (新产品)

Nano Cap^TM

Datasheet

6ch White LED Driver Built-in Current Driver

Boost DC/DC Converter for Automotive

BD82A26MUF-M

General Description

Key Specifications

This IC is a white LED driver for LCD backlight.

◼ Input Operating Voltage Range:

3.0 V to 48 V

It has 6ch 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 large 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 3.0 V to 48 V.

◼

Output LED Current Absolute Accuracy:

±5.0 %@80 mA

◼ DC/DC Oscillation Frequency: 200 kHz to 2420 kHz

◼ Operating Temperature:

◼ LED Maximum Current:

◼ LED Maximum Dimming Ratio: 20,000: 1@100 Hz

◼ LED1 to LED6 Pin Maximum Voltage: 50 V

-40 °C to +125 °C

150 mA/ch

Package

VQFN32FBV050

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

5.0 mm x 5.0 mm x 1.0 mm

Features

◼

Nano Cap^TMIntegrated^{(Note 1)}

AEC-Q100 Qualified^{(Note 2)}

Functional Safety Supportive Automotive Products

Current Driver for LED Drive 6ch

Current Mode Boost DC/DC Converters

Load Switch (M1) Control Pin

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

Analog + PWM Mix Dimming Available

Spread Spectrum Function

DC/DC Converter Oscillation Frequency External

Synchronization Function

Applications

◼

Automotive CID (Center Information Display) Panel

Navigation

Cluster Panel

HUD (Head Up Display)

Other Small and Medium Sized LCD Panels for

Automotive

◼

LSI Protect Functions (UVLO, OVP, TSD, OCPL)

LED Anode/Cathode Short Circuit Protection Function

LED Open/Short Protection Function

(Note 1) Nano Cap^TMis a trademark or a registered trademark of ROHM Co., Ltd. Nano Cap™ is a combination of technologies which allow stable operation

even if output capacitance is connected with the range of nF unit.

(Note 2) Grade 1

Typical Application Circuit

VCC

R_CSH

REG50

M1

C_VCC

EN

C_CP2

D1

32 31 30 29 28 27 26 25

EXP-PAD

1

EXP-PAD

24

C_REG25

REG25

VDISC

OVP

2

3

4

5

6

7

8

23

22

21

20

19

18

17

REG50

RT

R_FAIL2VREG

C_REG50

FAIL2

SHT

R_OVP1

L1

R_OVP2

D2

R_RT

SYNC

PWM

PLSET

COMP

GND

SYNC

PWM

EXP-PAD

VOUT

PD

PGND

OUTL

CSL

PD

R_PLSET2

C_PCR_PC

M2

R_G

R_PLSET1

R_CSL

EXP-PAD

9

10 11 12 13 14 15 16

R_DIMSEL2

R_DIMSEL1

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, No.7,944,189 and No.10,068,511.

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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 Rating............................................................................................................................................................11

Thermal Resistance......................................................................................................................................................................11

Recommended Operating Conditions...........................................................................................................................................12

Operating Conditions (External Constant Range).........................................................................................................................12

Electrical Characteristics...............................................................................................................................................................13

Typical Performance Curves.........................................................................................................................................................17

Functional Descriptions ................................................................................................................................................................19

PCB Application Circuit Diagram ..................................................................................................................................................36

List of External Components.........................................................................................................................................................37

Power Consumption Calculation Example....................................................................................................................................39

I/O Equivalence Circuit .................................................................................................................................................................40

Operational Notes.........................................................................................................................................................................41

Ordering Information.....................................................................................................................................................................43

Marking Diagram ..........................................................................................................................................................................43

Physical Dimension and Packing Information...............................................................................................................................44

Revision History............................................................................................................................................................................45

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Pin Configuration

(TOP VIEW)

EXP-PAD

32

31

30

29

28

27

26

25

1

2

3

4

5

6

7

8

24

23

22

21

20

19

18

17

REG25

REG50

RT

VDISC

OVP

FAIL2

SHT

SYNC

PWM

PLSET

COMP

GND

EXP-PAD

PD

PGND

OUTL

CSL

9

10

11

12

13

14

15

16

EXP-PAD

Pin Descriptions

Signal

type

(Note 1)

No.

Name

Function

Internal reference voltage 1: Used as the reference voltage for the internal circuit and charge

pump.

1

2

3

REG25

REG50

RT

A

Internal reference voltage 2: Used as the reference voltage for the internal circuit. 5 V is generated

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

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.

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

REG50 pin beforehand.

4

SYNC

I

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

signal.

5

6

PWM

I

Switching pulse number setting: Addition pulse 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 resistance value connected to the PLSET pin.

PLSET

A

Phase compensation 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

COMP

A

Small Signal Ground: Use to ground for the external components connected to the REG25,

REG50, RT, PLSET, COMP, ISET, DIMSEL, PD, SHT, and OVP pins.

8

9

GND

ISET

A

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.

DC dimming setting: The point at which PWM dimming and DC dimming are switched can be set

by the resistor connected between the DIMSEL pin and the GND pin. When using only PWM

dimming, short the DIMSEL pin with the GND pin.

10 DIMSEL

A

LED cathode connection 1: Open drain output of the current driver ch1 for LED drive. Connect to

the LED cathode.

11

12

13

LED1

LED2

LED3

P

LED cathode connection 2: Open drain output of the current driver ch2 for LED drive. Connect to

the LED cathode.

LED cathode connection 3: Open drain output of the current driver ch3 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: High current signal susceptible to impedance, including transient current.

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Pin Descriptions – continued

Signal

type

(Note 1)

No.

Name

Function

LED cathode connection 4: Open drain output of the current driver ch4 for LED drive. Connect to

the LED cathode.

14

15

16

LED4

LED5

LED6

P

LED cathode connection 5: Open drain output of the current driver ch5 for LED drive. Connect to

the LED cathode.

LED cathode connection 6: Open drain output of the current driver ch6 for LED drive. Connect to

the LED cathode.

Overcurrent protection detection input: The current flowing through Low side FET (M2) is

converted to voltage by the low side current detection resistor (R_CSL) and detected by the CSL pin.

When the overcurrent protection (OCPL) is activated, DC/DC converters are switched OFF.

17

CSL

A

Low side FET gate signal: Switching signal output of DC/DC converter. The OUTL pin should be

connected to Low side FET (M2) gate.

18

19

20

OUTL

PGND

PD

P

A

Large current ground: Use for ground for external components connected to the CSL and OUTL

pins.

Phase Delay setting: Connect the PD pin to the REG50 pin when using the Phase Delay function.

Connect the PD pin to the GND pin when the phase delay function is not used.

Resistor connection for LED short protection setting: LED short detection voltage can be set by

connecting a resistor (R_SHT) between the SHT pin and the GND pin. When LED short protection is

activated, the current driver is turned OFF only for the corresponding LED column.

21

22

SHT

A

Error output flag 2: Outputs the status of protective operation from the FAIL1 pin and the FAIL2

pin. Since these pins are open drain outputs, pulling up to the REG50 pin is recommended.

FAIL2

O

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

rises to 1.0 V or more, overvoltage protection (OVP) is activated, and DC/DC converters are

switched OFF. If OVP pin voltage is 0.3 V or less for 13.1 ms, Short Circuit Protection (SCP) is

activated, and both DC/DC converter and the current driver are turned OFF.

23

OVP

A

VOUT discharge: Connects to the output of DC/DC converters. When UVLO, TSD, or SCP

protective operation is performed, or when PWM Low section is monitored and the operation OFF

status is detected, DC/DC output voltage is discharged from the VDISC pin.

24

25

26

VDISC

FAIL1

LDSW

P

O

P

Error output flag 1: Outputs the status of protective operation from the FAIL1 pin and the FAIL2

pin. Since these pins are open drain outputs, we recommend pulling them up to the REG50 pin.

Output for driving the load switch gate: This is the signal output for driving the gate of the load

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

LDSW pin voltage = VCC voltage.

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.

27

28

29

CSH

VCC

EN

A

P

I

Power supply voltage input: The input operating voltage range is 3.0 V to 48 V, but when the IC is

started, VCC ≥ 5.0 V should be used. The decoupling capacitor (C_VCC) between the VCC pin and

the GND pin should be close to the IC pin.

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

level at 0.5 V or less, and judged as High level at 2.3 V or more. Avoid using a constant two state

input (0.5 V ≤ V_EN≤ 2.3 V).

30

31

CP

P

Charge pump output: Connect a capacitance (C_CP1) between the CP pin and the PGND pin.

Flying capacitor connection + side: Connect a capacitance (C_CP2) between the CPP pin and the

CPM pin.

CPP

Flying capacitor connection - side: Connect a capacitance (C_CP2) between the CPP pin and the

CPM pin.

32

CPM

P

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

EXP-

PAD

-

The center EXP-PAD and corner EXP-PAD are shorted inside the packaging.

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

impedance, including transient current.

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Block Diagram

VCC

CSH

LDSW

VOUT

Discharge

EN

VDISC

LDSW

Driver

VREF

REG50

REG25

PROTECT

Additional

Pulse

PLSET

RT

DC/DC

Control

LOGIC

REG50

OSC

SLOPE

+

OUTL

PGND

CSL

－

SSCG

PWM

COMP

SYNC

COMP

Error

AMP

－

+

LED1

LED2

LED3

LED4

LED5

LED6

Soft

Start

LDSW

Driver

Minimum

Channel

Selector

PROTECT

UVLO

DC/DC

Control

LOGIC

ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀFAIL

TSD

SCP

OCPH

FAIL1

FAIL2

ISET SCP

OCPL

OVP

OPEN Det

TW

SHORT Det

SHT

OVP

Current

Driver

Internal

CLK

REF

Voltage

Phase

Delay

PD

CP

PWM

Dimming

Control

DIMSEL

ISET

CPP

ISET

CH5 CH6

CH1 CH2 CH3 CH4

Charge

Pump

CPM

CP

Current Driver

GND

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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 REG50 pin. REG50

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 C_REG50= 2.2 μF to the REG50 pin as the capacitance for the phase compensation. Note that if C_REG50is

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 0.2 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

voltage. Then, after 13.1 ms elapses, the load switch is turned ON. At this time, if the voltage between VCC-CSH is 0.2 V

or more, the load switch is turned OFF again. If the voltage between VCC-CSH is 0.2 V or less, Self Diagnosis is performed

and restarted. For Self Diagnosis, refer to "3 Startup Characteristics and Effective Section of Each Protection Function".

Only the FAIL2 pin goes Low when the input overcurrent protection is detected.

3 VOUT Discharge

Output voltage discharge circuit. The LEDs may flicker if activated with charges remaining on VOUT. Therefore, VOUT

must be discharged at startup. Discharge times may be prolonged only by discharge paths such as the resistor for OVP

setting, so an output voltage discharge circuit (VOUT discharge function) is provided. Residual charges in the output are

discharged when DC/DC converters are turned OFF (when the EN falls or the protective function is activated).

4 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. Input

the clock signal to be input from the SYNC pin before the Self Diagnosis is completed. For Self Diagnosis, refer to "3 Startup

Characteristics and Effective Section of Each Protection Function".

5 SSCG (Spread Spectrum Clock Generator)

Spread spectrum circuit. The spread spectrum function (SSCG) is activated by shorting the SYNC pin and the REG50 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 cycle

is 128/set oscillation frequency.

6 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.

7 Minimum Channel Selector

Selector circuit for detecting LED pin voltages. Selects the lowest pin voltage among LED1 to LED6 pin voltages and input

it in Error AMP.

8 Error AMP (Error Amplifier)

This is an error amplifier that takes the smallest values of the LED1 to LED6 pin voltage and LED control voltage as inputs.

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

9 Soft Start

Soft start circuit for DC/DC converters. This function is used to suppress a steep increase in the coil 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).

10 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.

11 Additional Pulse

This circuit adds switching pulses for DC/DC converters. With the Additional pulse function, the LED current can be supplied

stably even when the PWM dimming ratio decreases.

12 DC/DC Control LOGIC

This circuit generates the final logic of Low side FET gate signal output from the OUTL pin.

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Description of Blocks - continued

13 Internal CLK

This circuit generates the internal reference clock. It is a clock of 20 MHz and used as a counter or sampling frequency.

14 Phase Delay

This circuit shifts the phase of LED pin output during PWM dimming. Phase Delay function can be used by shorting the PD

pin to the REG50 pin.

15 Dimming Control

This circuit controls the dimming ratio during PWM dimming. PWM dimming and DC dimming can be automatically switched

PWM dimming and DC dimming can be automatically switched and controlled by applying a voltage (resistor division of

REG50) to the DIMSEL pin. This provides both minute dimming (PWM dimming) at low brightness levels and support for

high brightness ranges (DC dimming).

16 Charge Pump

Charge pump circuit. The charge pump output voltage is used for the output drive voltage of the current driver, and can

output a stable LED current even when the VCC input voltage is low. By connecting the capacitance (C_CP1) between the

CP pin and ground and the capacitance (C_CP2) between the CPP-CPM pin, a voltage twice the REG25 pin voltage can be

output from the CP pin. 10 μF is recommended for C_CP1and 2.2 μF is recommended for C_CP2. When the charge pump

function is not used, do not connect capacitance between the CPP-CPM pin and short-circuit the CP pin with the REG50

pin.

17 Current Driver / ISET

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

18 PROTECT

Outputs the status of protective operation from the FAIL1 pin and the FAIL2 pin. Since these pins are open drain outputs,

connect them to the REG50 pin with resistors. If the protection status is not monitored, turn the FAIL1 pin and the FAIL2

pin to OPEN or connect to the GND pin.

18.1 UVLO (Under Voltage Lockout)

Under Voltage Lockout. When the VCC is 2.8 V or less or the REG50 pin voltage is 2.7 V or less, Under Voltage

Lockout (UVLO) is activated, and the load switch (M1), DC/DC converter, and current driver turn OFF. When VCC

becomes 3.2 V or more and the REG50 pin voltage becomes 3.1 V or more, UVLO is released and the IC restarts

from Self Diagnosis. When a UVLO is detected, the outputs of the FAIL1 pin and the FAIL2 pin do not change. When

the FAIL1 pin and the FAIL2 pin are pulled up to REG50, FAIL1 pin and FAIL2 pin voltage will also drop as REG50

decreases.

18.2 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 abnormal output current. When the chip temperature rises to 175 °C or more, the

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

turned OFF, and only the FAIL2 pin is turned Low. When the chip temperature falls 150 °C or less, TSDLED is

released, the IC restarts from Self Diagnosis, and the FAIL2 pin returns to High.

18.3 TSDREG (Thermal Shutdown for REG50)

This is a temperature protection circuit that monitors the vicinity of the REG50 pin on the chip. Prevents chip

temperature rising due to the REG50 pin failure. When the chip temperature rises to 175 °C or more, the temperature

protection circuit (TSDREG) is activated, and REG50 pin voltage, load switch (M1), DC/DC converter, and current

driver turn OFF. When the FAIL1 pin and the FAIL2 pin are pulled up to the REG50 pin, FAIL1 pin and FAIL2 pin

voltages drop as REG50 pin voltage is turned OFF, and both are output to the Low level. When the FAIL1 pin and

the FAIL2 pin are pulled up to an external power supply, both the FAIL1 pin and the FAIL2 pin are output to High.

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

18.4 TW (Thermal Warning)

Thermal Warning Circuit. When the chip temperature rises to 140 °C or more, the Thermal Warning Circuit (TW)

activates and only the FAIL1 pin goes Low. When the chip temperature falls 130 °C or less, the TW is released and

the FAIL1 pin returns to High.

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18. PROTECT – continued

18.5 OCPL (Over Current Protection for Low side)

The voltage is detected by the low side current detection resistor (R_CSL) for the current flowing through Low side FET

(M2). When CSL pin voltage rises to 0.3 V or more, the overcurrent protection (OCPL) is activated and only the

switching of DC/DC converter is stopped. If CSL pin voltage falls less than 0.3 V, the overcurrent protection is

released and switching resumes. When the OCPL is detected, the outputs of the FAIL1 pin and the FAIL2 pin do not

change.

18.6 OVP (Over Voltage Protection)

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

becomes 1.0 V or more, the output overvoltage protection circuit (OVP) activates and only the switching of DC/DC

converter is stopped. When OVP pin voltage falls 0.95 V or less, OVP is released. Only the FAIL1 pin goes Low

when OVP is detected.

18.7 OPEN Det (LED Open Detection)

LED open protection circuit. When any of LED1 to LED6 pin voltages is 0.3 V or less and OVP pin voltage is 1.0 V

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

corresponding LED column. LED open protection is released when V_EN= Low or UVLO is detected. When LED open

is detected, only the FAIL2 pin goes Low.

18.8 SHORT Det (LED Short Detection)

LED short protection circuit. When LED pin voltage is higher than the threshold set by the SHT pin for 13.1 ms, the

LED short protection (SHORT Det) is activated and the current driver is latched OFF only for the corresponding LED

column. The counter is reset when LED pin voltage does not satisfy the detection condition prior to the LED short

protection being activated. 10 times the voltage input to the SHT pin becomes the short detection threshold. When

the SHT pin is connected to GND, the short detection threshold is 4.5 V. Short the SHT pin to GND or set to the

voltage application state and do not set it to OPEN status. LED short protection is released when V_EN= Low or a

UVLO is detected. Counters of 13.1 ms are counted up only when Duty of LED current is ON. Therefore, the duration

until LED short protection is detected varies depending on the input PWM Duty and PWM-DC dimming switching

point. Only the FAIL2 pin goes Low when LED short protection is detected. LED short protection is detectable when

ON pulse width of the LED current is 20 μs or more.

18.9 SCP (Short Circuit Protection)

Short Circuit Protection circuit. If any of the LED1 to LED6 pin is 0.3 V or less or OVP pin voltage is 0.3 V or less for

13.1 ms, the Short Circuit Protection (SCP) is activated, and the load switch (M1), DC/DC converter, and current

driver turn OFF. However, the counters are reset when each pin voltage no longer satisfies the requirement prior to

the SCP is activating. The SCP is released when V_EN= Low or a UVLO is detected. When SCP is detected, only the

FAIL2 pin goes Low.

DC/DC converters also attempt to output a 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 load conditions, the OVP pin may

become 1.0 V or more prior to the SCP being activated, and the LED open protection may be activated first. In this

case, the current driver will be turned OFF only in the grounded LED pin, but the LEDs will remain lighting with the

current control lost because of a short circuit as well. Even when LED open protection is detected, the FAIL2 pin

goes Low. Abnormality can be detected by monitoring this.

18.10 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 0.2 V or more

continues for 10 μs or more, the input overcurrent protection (OCPH) is activated, and the load switch (M1), DC/DC

converter, and current driver turn OFF. Then, after 13.1 ms elapses, the load switch is turned ON. At this time, if the

voltage between VCC-CSH is 0.2 V or more, the load switch, DC/DC converter, and current driver are turned OFF

again. If the voltage between VCC-CSH is less than 0.2 V, Self Diagnosis is performed and restarted. For Self

Diagnosis, refer to "3 Startup Characteristics and Effective Section of Each Protection Function". When the input

overcurrent protection is detected, the FAIL2 pin goes Low.

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18 PROTECT – continued

18.11 ISET Pin Fault Protection (ISET-GND Short Circuit Protection)

ISET pin fault protection circuit. When the resistance value connected to the ISET pin becomes 1 kΩ or less, ISET

error protection is activated, and the load switch (M1), DC/DC converter, and current driver are turned OFF. When

the resistor connected to the ISET pin becomes 15 kΩ or more, ISET error protection is released, and the load switch

(M1), DC/DC converter, and current driver turn ON. When ISET-GND short protection is detected, only the FAIL2

pin goes Low.

18.12 OVP Pin Fault Protection

OVP pin fault protection circuit. If OVP pin voltage is 2.3 V or more or 0.2 V or less or VDISC pin voltage is 47.5 V

or more in the Self Diagnosis status after the EN pin starts, OPEN/SHORT error of the resistor connected to OVP is

detected and OVP pin fault protection is activated. At this time, the load switch (M1), DC/DC converter, and current

driver turn OFF. When V_EN= Low or a UVLO is detected, OVP pin fault protection is released. When OVP pin fault

protection is detected, both the FAIL1 pin and the FAIL2 pin are set to 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 typical values)

Detect Operation

Detect Condition

No.

Function

Load

Switch Switching

DC/DC Current FAIL1

FAIL2

[Detect]

[Release]

(Note 1)

Driver

OFF

VCC ≥ 3.2 V

and

Under Voltage

VCC ≤ 2.8 V

1

2

3

OFF

High

Low

Lockout

(UVLO)

or V_REG50≤ 2.7 V

V_REG50≥ 3.1 V

Thermal

OFF

Shutdown

(TSDLED)

Thermal

Shutdown^{(Note 2)}

(TSDREG)

Tj ≥ 175 °C

Tj ≥ 140 °C

Tj ≤ 150 °C

Tj ≤ 130 °C

High

Low

(Note 2)

Low

(Note 2)

Thermal

Warning

(TW)

4

5

6

ON

OFF

ON

Low

High

Overcurrent

V_CSL≥ 0.3 V

V_OVP≥ 1.0 V

V_CSL< 0.3 V

High

Low

High

Protection

(OCPL)

Overvoltage

V_OVP≤ 0.95 V

Protection

(OVP)

Detects

V_EN= Low

or

Detect

LED

LED Open

Protection

(OPEN Det)

V_LEDn≤ 0.3 V

and V_OVP≥ 1.0 V^{(Note 6)}

Latch

Low

7

8

9

ON

High

OFF

UVLO

Detects

V_EN= Low

or

Detects

V_LEDn≥ V_SHTx 10

Detect

LED

LED Short

Latch

Low

Protection

(SHORT Det)

and V_LEDn≥ 4.5 V

for 13.1 ms or more^{(Note 3)(Note 6)}

OFF

UVLO

Detects

V_EN= Low

or

Detects

Short Circuit

Latch

Low

OFF

V_LEDn≤ 0.3 V or V_OVP≤ 0.3 V

for 13.1 ms or more^{(Note 6)}

Protection

(SCP)^{(Note 4)}

UVLO

Input

Detects

VCC-V_CSH

< 0.2 V

OFF

Overcurrent

10

11

OFF

VCC-V_CSH≥ 0.2 V

for 10 μs or more

High

Low

(Note 5)

Protection

(OCPH)^{(Note 4)}

ISET Pin

OFF

Fault Protection

(ISET SCP)

R_ISET≤ 1.0 kΩ

R_ISET≥ 15 kΩ

At Self Diagnosis

V_OVP≥ 2.3 V

Detects

V_EN= Low

or

OVP Pin

Latch Latch

Low Low

OFF

12

Fault Protection

or V_OVP≤ 0.2 V

or V_VDISC≥ 47.5 V

UVLO

(Note 1) When the EN pin is Low, if FAIL1, FAIL2 is pulled up to the REG50 pin, FAIL1 = Low, FAIL2 = Low. When FAIL1, FAIL2 is pulled up to an external power

supply, FAIL1 = High, FAIL2 = High.

(Note 2) Thermal shutdown (TSDREG) detects heat generation in the event of the REG50 pin failure and turns all circuit OFF, including the REG50 pin. When

FAIL1, FAIL2 is pulled up to the REG50 pin, FAIL1 = Low, FAIL2 = Low. When FAIL1, FAIL2 is pulled up to an external power supply, FAIL1 = High, FAIL2

= High.

(Note 3) LED pin voltage of at least 1ch shall be less than V_LEDCTL(Min)x 1.1. When LED pin voltages of all channels are 1.4 V or more, the LED short protection does

not operate. In addition, since the 13.1 ms counter is counted up only when Duty of the LED current is ON, the time until SHORT Det is detected varies

depending on PWM Duty.

(Note 4) 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 5) When 13.1 ms elapses after the load switch is turned OFF, the load switch turns ON. At this time, when the voltage between VCC-CSH ≥ 0.2 V, the load

switch is turned OFF again. When the voltage between VCC-CSH < 0.2 V, Self Diagnosis is performed and restarted. For Self Diagnosis, refer to "3 Startup

Characteristics and Effective Section of Each Protection Function".

(Note 6) n = 1 to 6

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BD82A26MUF-M

Absolute Maximum Rating (Ta = 25 °C)

Parameter

Symbol

V_OVP, V_VDISC, V_LDSW, V_CSH, VCC

VCC - V_LDSW

Rating

Unit

V

OVP, VDISC, LDSW, CSH, VCC Pin Voltage

Voltage Between VCC-LDSW Pin

-0.3 to +50

-0.3 to +7.0

V

LED1, LED2, LED3,

V_LED1, V_LED2, V_LED3,

-0.3 to +50

V

LED4, LED5, LED6 Pin Voltage

RT, PLSET, COMP, ISET, DIMSEL,

CSL, OUTL Pin Voltage

V_LED4, V_LED5, V_LED6

V_RT, V_PLSET, V_COMP, V_ISET

V_DIMSEL, V_CSL, V_OUTL

,

-0.3 to V_REG50

-0.3 to +7.0

V

REG25, REG50 Pin Voltage

V_REG25, V_REG50

SYNC, PWM, PD, SHT, FAIL2, FAIL1,

EN, CP, CPP, CPM Pin Voltage

V_SYNC, V_PWM, V_PD, V_SHT,V_FAIL2

V_FAIL1, V_EN, V_CP, V_CPP, V_CPM

,

Storage Temperature Range

Tstg

-55 to +150

150

°C

Maximum Junction Temperature

Tjmax

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)}

VQFN32FBV050

Junction to Ambient

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

θ_JA

97.3

10.0

30.7

7.0

°C/W

Ψ_JT

(Note 1) Based on JESD51-2A (Still-Air). The BD82A26MUF-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

Copper Pattern

Thickness

70 μm

Footprints and Traces

74.2 mm x 74.2 mm

35 μm

74.2 mm x 74.2 mm

(Note 5) This thermal via connect with the copper pattern of layers 1,2, and 4. The placement and dimensions obey a land pattern.

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BD82A26MUF-M

Recommended Operating Conditions

Operating Range

Parameter

Symbol

Unit

Min

3.0

200

0.1

Max

48

Power Supply Voltage^{(Note 1)}

VCC

f_OSC

V

DC/DC Oscillation Frequency Range

PWM Frequency Range^{(Note 2)}

2420

25

kHz

f_PWM

External Synchronized

Frequency Range^{(Note 3)}

External Synchronized

Pulse Duty Range^{(Note 4)}

Higher of 200

or f_OSCx 0.8

Lower of 2420

or f_OSC

f_SYNC

kHz

%

f_SDUTY

40

60

LED Current Setting Range^{(Note 5)}

I_LED

50

150

mA

°C

Operating Temperature

Topr

-40

+125

(Note 1) When IC are started, VCC ≥ 5.0 V should be set.

VCC (Min) = 3.0 V is the minimum value of VCC that can operate the IC alone. The minimum value of power supply voltage that can be set varies depending

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. Check with the actual application evaluation.

(Note 3) When the external synchronization function is not used, connect the SYNC pin to the REG50 pin (SSCG = ON) or connect to the GND pin (SSCG = OFF)

or OPEN (SSCG = OFF).

(Note 4) When using the external synchronous function, switching from the external synchronous state to the internal oscillation frequency is not possible during

stable operation.

(Note 5) 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

0.10

1.0

Typ

0.22

2.2

31.2

33.3

-

Max

0.47

4.7

50.0

45.0

-

REG25 Capacitance

C_REG25

C_REG50

R_ISET

R_RT

μF

kΩ

μF

kΩ

REG50 Capacitance

LED Current Setting Resistor

Oscillation Frequency Setting Resistor

Input Capacitance 1

18.0

4.0

C_VCC

1^{(Note 6)}

10^{(Note 6)}

20^{(Note 6)}

4.7

(Note 7)

Input Capacitance 2

C_INVCC

C_VOUT

C_CP1

-

Output Capacitance

-

100

20.0

4.7

20

Charge Pump Capacitance 1

Charge Pump Capacitance 2

Resistor for the OVP Pin Setting (Low Side)

Resistor for the OVP Pin Setting (High Side)

10.0

2.2

-

C_CP2

1.0

R_OVP1

R_OVP2

10

300

-

800

Resistor for Unused Channels Setting

(Low Side)^{(Note 8)}

R_LED1

10

20

30

kΩ

Resistor for Unused Channels Setting

(High Side)^{(Note 8)}

R_LED2

40

100

180

kΩ

(Note 6) Set the capacitance so that it does not fall below the minimum value in consideration of temperature characteristics, DC bias characteristics, etc.

(Note 7) C_INVCCmeans the sum of C_INand C_VCC. If a capacity of 10 μF or more is connected to C_VCC, the capacity of C_INis not required.

(Note 8) The ratio of R_LED1to R_LED2should be between 1:4 and 1:6.

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BD82A26MUF-M

Electrical Characteristics

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

Standard Value

Unit

V

Conditions

Parameter

VCC Voltage at Startup

Operating VCC Voltage^{(Note 1)}

Circuit Current

Symbol

VCC_start

VCC_active

I_CC

Min

5.0

Typ

Max

48.0

12.0

-

V

3.0

48.0

20

V_EN= 5 V, V_SYNC= 0 V,

V_PWM= 0 V, C_VCC= 10 μF,

R_RT= OPEN, R_ISET= OPEN

-

mA

μA

Standby Current

I_ST

0

20

V_EN= Low

[REGURATOR]

I_REG50= 5 mA load,

C_REG50= 2.2 μF

Reference Voltage

V_REG50

4.5

5.0

5.5

V

[DC/DC Converter]

OUTL Pin High Side ON Resistor

OUTL Pin Low Side ON Resistor

LED Control Voltage 1

R_ONLH

R_ONLL

V_LEDCTL1

V_LEDCTL2

3.7

1.2

7.5

2.5

15.0

5.0

Ω

V

I_OUTL= 10 mA load

I_OUTL= 10 mA input

R_ISET= 50 kΩ

0.4

0.5

0.6

LED Control Voltage 2

0.68

0.83

0.98

R_ISET= 18 kΩ

R_ISET= 18 kΩ,

COMP Sink Current

I_COMPSINK

170

250

330

μA

V_COMP= 1.0 V,

V_LEDn= 1.5 V (n = 1 to 6)

R_ISET= 18 kΩ,

COMP Source Current

Oscillation Frequency 1

I_COMPSOURCE

-330

-250

-170

V_COMP= 1.0 V,

V_LEDn= 0.0 V (n = 1 to 6)

f_OSC1

f_OSC2

D_{UTY_MAX}

t_SWOFF

kHz

%

R_RT= 33.3 kΩ

R_RT= 4.0 kΩ

R_RT= 33.3 kΩ

270

1980

96.5

-

300

2200

98.0

67

330

2420

-

Oscillation Frequency 2

Max Duty^{(Note 2)(Note 3)}

Switching OFF Time^{(Note 3)}

[Charge Pump]

130

ns

Charge Pump Frequency

f_CP

250.0

4.5

312.5

5.0

375.0

5.5

kHz

V

C_CP2= 2.2 μF

C_CP1= 10 μF, C_CP2= 2.2 μF,

V_REG50= 3.0 V

Charge Pump Output Voltage

V_CP

(Note 1) The minimum value of 3.0 V for VCC is the minimum value of VCC that can operate the IC alone. The minimum value of power supply voltage that can be

set varies depending on the connected LED load and external components.

(Note 2) For the switching Duty required for applications, refer to the 2.13 Switching Duty Required for Applications.

(Note 3) Max Duty can be calculated using (1-t_SWOFF) x f_OSC

.

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BD82A26MUF-M

Electrical Characteristics – continued

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

Standard Value

Typ

Parameter

[PROTECT]

Symbol

Unit

Conditions

Min

Max

UVLO Release Voltage (VCC)

UVLO Detect Voltage (VCC)

UVLO Release Voltage (REG50)

UVLO Detect Voltage (REG50)

OCP Detect Voltage

V_UVLOVCC1

V_UVLOVCC2

V_UVLOREG1

V_UVLOREG2

V_OCPL

3.00

2.65

2.90

2.55

0.27

0.17

4.4

3.20

2.80

3.10

2.70

0.30

0.20

5.4

3.40

2.95

3.30

2.85

0.33

0.23

6.4

V

VCC: Sweep up

VCC: Sweep down

V_REG50: Sweep up

V_REG50: Sweep down

V_CSL: Sweep up

Input OCP Detect Voltage

V_OCPH

VCC-V_CSH: Sweep down

LDSW Operation Voltage

at Input OCP Release

V_CSH= VCC

VCC-V_LDSW

V_LDSW

OVP Detect Voltage 1

V_OVP1

0.95

0.03

1.00

0.05

1.05

0.07

V_OVP= Sweep up

V_OVP= Sweep down

V_VDISC= Sweep up

OVP Detect Voltage 1

Hysteresis Width

OVP Detect Voltage 2

(VDISC Pin)

V_OVP1HYS

V_OVP2

45

47

49

V

V_LEDn= Sweep down

(n = 1 to 6),

V_OVP> 2.0 V

LED Open Protection Detect

Voltage

V_OPEN

0.2

0.3

0.4

LED Anode SCP Detect Voltage

LED Cathode SCP Detect Voltage

V_SCP1

V_SCP2

t_SCP1

t_SCP2

0.2

0.3

0.4

V

V_OVP= Sweep down

V_LEDn= Sweep down

(n = 1 to 6)

LED Anode SCP Detect

Delay Time

10.5

13.1

15.7

ms

LED Cathode SCP Detect

Delay Time

SHT = GND,

V_LEDn= Sweep up

(n = 1 to 6)

LED Short Protection Detect

Voltage 1

V_SHORT1

4.2

9

4.5

10

4.8

11

V

SHT = 1 V,

V_LEDn= Sweep up

(n = 1 to 6)

LED Short Protection Detect

Voltage 2

V_SHORT2

LED Short Protection Detect

Delay Time

PWM = 100 %

DIMSEL = GND

t_SHORT

R_FAIL1

R_FAIL2

10.5

13.1

15.7

2.0

ms

kΩ

FAIL1 Pin ON Resistor

FAIL2 Pin ON Resistor

-

2.0

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BD82A26MUF-M

Electrical Characteristics – continued

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

Standard Value

Typ

Parameter

[Current Driver]

Symbol

Unit

Conditions

Min

Max

R_ISET= 31.2 kΩ,

(Note 3)

LED Current Absolute Variation 1

I_LEDn

76.0

80.0

-

84.0

3.0

-

mA

%

PWM = 100 %^{(Note 2)}

LED Current Relative Variation

1^{(Note 1)}

R_ISET= 31.2 kΩ,

PWM = 100 %^{(Note 2)}

I_LEDREL

0

-

ISET-GND

Resistor

Short

Protection

R_ISETLIM

1.0

kΩ

DIMSEL = GND

f_PWM= 100 Hz to 25 kHz,

I_LEDn= 50 mA to 150 mA

(n = 1 to 6)

PWM Dimming Minimum Pulse

Width

t_PWMMIN

0.5

-

μs

PWM Dimming Frequency

Phase Delay Time

f_PWM

t_PD

0.1

-

25.0

-

kHz

μs

10

V_PD= 5 V

PWM Low Section Detect Time

[PLSET Pin]

t_PWML

10.5

13.1

15.7

ms

V_REG50

x 0.10

V_REG50

x 0.30

V_REG50

x 0.50

V_REG50

x 0.70

V_REG50

x 0.90

V_REG50

x 0.15

V_REG50

x 0.35

V_REG50

x 0.55

V_REG50

x 0.75

No Additional Pulse Setting Voltage

Additional 2 Pulse Setting Voltage

Additional 4 Pulse Setting Voltage

V_PLSET0

V_PLSET2

V_PLSET4

V_PLSET8

V_PLSET12

I_PLSET

GND

V

V_REG50

x 0.25

V_REG50

x 0.45

V_REG50

x 0.65

V_REG50

x 0.85

V

Additional 8 Pulse Setting Voltage

Additional 12 Pulse Setting Voltage

PLSET Pin Inrush Current

[DIMSEL Pin]

V

V_REG50

+1

V

-1

0

µA

Setting Voltage for PWM Dimming

only

V_REG50

x 0.10

V_REG50

x 0.30

V_REG50

x 0.70

V_REG50

x 0.90

V_REG50

x 0.15

V_REG50

x 0.35

V_REG50

x 0.75

V_DIMSEL1

V_DIMSEL2

V_DIMSEL3

V_DIMSEL4

I_DIMSEL

GND

V

PWM-DC Switching 12.5 %

Setting Voltage

V_REG50

x 0.25

V_REG50

x 0.65

V_REG50

x 0.85

PWM-DC Switching 25 %

Setting Voltage

V

PWM-DC Switching 50 %

Setting Voltage

V_REG50

+1

V

DIMSEL Pin Inrush Current

-1

0

µA

(Note 1) I_LEDREL= (Maximum value of I_LED1to I_LED6- Minimum value of I_LED1to I_LED6) / (Maximum value of I_LED1to I_LED6+ Minimum value of I_LED1to I_LED6) x 100

(Note 2) When PWM Duty is lower than 100 %, it is larger than the variation described.

(Note 3) n = 1 to 6

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BD82A26MUF-M

Electrical Characteristics – continued

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

Standard Value

Typ

Parameter

Symbol

Unit

Conditions

Min

Max

[EN Pin]

Input High Voltage (EN)

Input Low Voltage (EN)

V_INH1

V_INL1

R_IN1

2.3

-

V

0.5

150

Input Resistor (EN)

50

100

kΩ

V_EN= 5 V

[PWM, SYNC Pin]

Input High Voltage (PWM, SYNC)

Input Low Voltage (PWM, SYNC)

Input Resistor (PWM, SYNC)

V_INH2

V_INL2

R_IN2

2.3

-

V

0.5

150

50

100

kΩ

V_PWM= 5 V, V_SYNC= 5 V

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BD82A26MUF-M

Typical Performance Curves

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

20

5.5

5.4

5.3

5.2

5.1

5.0

4.9

4.8

4.7

4.6

4.5

Ta = -40 ˚C

16

Ta = +25 ˚C

Ta = +125 ˚C

12

8

4

0

-40 -20

0

20 40 60 80 100 120

3

12

21

30

39

48

Temperature : Ta [°C]

Power Supply Voltage : VCC [V]

Figure 2. Circuit Current vs Power Supply Voltage

Figure 3. Reference Voltage vs Temperature

330

320

310

300

290

280

270

2.42

2.38

2.34

2.30

2.26

2.22

2.18

2.14

2.10

2.06

2.02

1.98

-40 -20

0

20 40 60 80 100 120

-40 -20

0

20 40 60 80 100 120

Temperature : Ta [°C]

Figure 4. Oscillation Frequency 1 vs Temperature

(R_RT= 33.3 kΩ)

Figure 5. Oscillation Frequency 2 vs Temperature

(R_RT= 4.0 kΩ)

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BD82A26MUF-M

Typical Performance Curves – continued

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

90

80

70

60

50

40

30

20

10

82.4

82.0

81.6

81.2

80.8

80.4

80.0

79.6

79.2

78.8

78.4

78.0

77.6

0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

-40 -20

0

20 40 60 80 100 120

LED Voltage : V_LEDn[V]

Temperature : Ta [°C]

Figure 6. LED Current vs LED Voltage

(Ta = 25 °C, R_ISET= 31.2 kΩ, n = 1 to 6)

Figure 7. LED Current vs Temperature

(R_ISET= 31.2 kΩ, n = 1 to 6)

100

95

90

85

80

75

70

100

95

90

85

80

75

70

50

60

70

80

90 100 110 120

50

60

70

80

90 100 110 120

LED Current : I_LEDn[mA/ch]

Figure 8. Efficiency 1 vs LED Current

(Ta = 25 °C, R_RT= 33.3 kΩ, n = 1 to 6,

Figure 9. Efficiency 2 vs LED Current

(Ta = 25 °C, R_RT= 4.0 kΩ, n = 1 to 6,

Number of LED Series = 12, Number of LED Parallel = 6)

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BD82A26MUF-M

Functional Descriptions

1 Current Driver

This model has a built-in 6ch current driver. The LED current setting range per channel is 50 mA to 138 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

1.3 Phase Delay Function

1.2 Dimming Control of LED Current

1.2.1 When Using only PWM Dimming

1.2.2 When Switching Between PWM Dimming and

DC Dimming Automatically

1.4 LED Pin Handling of Unused Channels

1.5 PWM Low Section Detect Function

1.6 When Setting the LED Current Above 150 mA

1.1 How to Set LED Current

The LED current I_LEDcan be calculated using the following equation.

퐼_퐿퐸퐷= 2.5 × 10⁶/푅_ꢀ푆퐸푇

[mA]

R_ISETrepresents the resistance value that is connected between the ISET pin and the GND pin. A resistor of 18 kΩ to 50

kΩ is recommended for R_ISET

.

When R_ISET≤ 1.0 kΩ, ISET pin short protection is activated and the output of the LED current is stopped.

I_LEDvs R_ISET

Resistance Setting Example

150

LED Current

R_ISET

[kΩ]

Value

[mA]

140

130

50.0

31.2

25.0

20.8

18.0

50

80

120

110

100

90

100

120

138

80

70

60

50

18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

R_ISET[kΩ]

Figure 10. I_LEDvs R_ISET

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1 Current Driver – continued

1.2 Dimming Control of LED Current

The LED current can be controlled by On Duty of the pulse signal (input PWM signal) input to the PWM pin from the outside

of the IC. Changing the input PWM frequency is prohibited because it may cause operation failure. When using Phase

Delay function (PD = High) alternatively, when using DC dimming, the input PWM signal is sampled synchronously with

the IC Internal CLK = 20 MHz (Typ).

Sampling of Input PWM Signal (Synchronization with IC Internal CLK) or Not

Do Not Use Phase Delay

Use Phase Delay Function

Function.

Synchronized with IC Internal

Without Synchronization

Use only PWM Dimming

CLK

Synchronized with IC Internal

CLK

Use PWM Dimming and DC

Dimming

Synchronized with IC Internal

CLK

To prevent flickering due to sampling, if the input PWM pulse width changes within ±2 CLK of the IC Internal CLK, the

change will not be reflected. In the example shown below, even if the input PWM width changes within the range of A,

since the sampled input PWM signal changes within ±2 CLK, the change is not reflected.

A

Input PWM

from External IC

50 ns (Typ)

IC Internal CLK

+2 CLK

PWM Signal

after Sampling

-2 CLK

Figure 11. Section That Does Not Accept Changes in Input PWM Width

Also, if PWM = High is detected for twice the PWM period, the IC recognizes that PWM = 100 % is input, and the LED

current is always ON.

The current dimming control can be selected from the following two methods.

1.2.1 When Using only PWM Dimming

When using only PWM dimming, short the DIMSEL pin with GND pin. The LED current can be controlled according to

On Duty of the input PWM signal. However, in the area where the LED current ON time is less than 0.5 μs or OFF time

is less than 0.5 μs, the pulse time is shorter than the PWM dimming minimum pulse width, so it cannot be used regularly.

It is okay to use this area transiently, so it is also possible to set PWM Duty = 0 % and 100 %. The step width of the input

PWM Duty should be 0.25 μs or more. If the step width of the input PWM Duty is less than 0.25 μs, the LEDs may flicker.

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1.2 Dimming Control of LED Current – continued

1.2.2 When Switching Between PWM Dimming and DC Dimming Automatically

Dimming control can be performed by automatically switching between PWM dimming and DC dimming. The point for

switching between PWM dimming and DC dimming is selected from three types: 50 %, 25 %, or 12.5 %. The point at

which PWM dimming and DC dimming are switched can be set using DIMSEL pin voltages as shown in the table below.

If the switching point for PWM-DC dimming is 12.5 %, Duty of the output LED current is 8 times the input PWM Duty, 4

times for 25 %, and 2 times for 50 %.

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

PWM dimming minimum pulse width, and therefore it cannot be used regularly. For example, if the switching point for

PWM-DC dimming is 12.5 % and the PWM frequency is 200 Hz, the operation may become unstable if a PWM Duty

within 625 μs ±0.5 μs (the range where the ON time of the LED current is less than 0.5 μs) is constantly input. There is

no problem with using this area transiently.

PWM-DC Dimming Switching Point Setting

IC

REG50

Resistance Example

PWM-DC

R_DIMSEL2

Dimming

Switching

Point

R_DIMSEL1

R_DIMSEL2

DIMSEL

Dimming

Control

Current

Driver

PWM Dimming

only

R_DIMSEL1

DIMSEL-GND Shorting

LED1

~

LED6

39 kΩ

91 kΩ

39 kΩ

12.5 %

25 %

PWM

DIMSEL-REG50 Shorting

50 %

Figure 12. How to Set PWM-DC Dimming Switching Point

LED Current

（When "No DC dimming" is set to 1）

1

PWM Dimming

0.5

DC

Dimming

0.25

0

DC Dimming

0.125

0

Input PWM

Duty [%]

Input PWM

Duty [%]

Input PWM

Duty [%]

50

100

50

100

50

100

Switch at 50 %

Switch at 25 %

Switch at 12.5 %

Figure 13. PWM-DC Dimming Switching Points 50 %, 25 %, and 12.5 %

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1 Current Driver – continued

1.3 Phase Delay Function

This model has a built-in Phase Delay function that can shift the phase of the timing when LED1 to LED6 current during

PWM dimming. The timing chart for Phase Delay is shown below. (∆t = 10 μs) When using Phase Delay function, short

the PD pin to the REG50 pin. When not using Phase Delay function, connect the PD pin to the GND pin.

Phase Delay function is available when the PWM frequency is 10 kHz or less.

PWM

t1

LED1 Current

t1

Δt

LED2 Current

t1

Δt

LED3 Current

t1

Δt

LED4 Current

t1

Δt

LED5 Current

t1

Δt

LED6 Current

t1

DC/DC Switching

Figure 14. Phase Delay Operation

t1

PWM

LED1 Current

LED2 Current

Δt

t1

LED3 Current

LED4 Current

LED5 Current

t1

LED6 Current

t1

DC/DC Switching

Figure 15. Phase Delay Operation for PWM Min Duty

t1

PWM

LED1 Current

LED2 Current

t1

Δt

t1

Δt

LED3 Current

LED4 Current

LED5 Current

t1

Δt

t1

Δt

t1

Δt

LED6 Current

t1

DC/DC Switching

Figure 16. Phase Delay Operation for PWM Max Duty

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1 Current Driver – continued

1.4 LED Pin Handling of Unused Channels

This model has six built-in constant current circuits.

By setting the PWM pin to High, current can be supplied to the LED

pin and LED current can be set by inserting a resistor between the

ISET pin and the GND pin.

The LED current setting that can be supplied per row is 50 mA to

150 mA.

For unused channels, pull up the LED pin (LED1 to LED6) to

REG50 with 100 kΩ and pull down to GND with 20 kΩ.

To select unused channels definitely, the capacitance value to be

connected to the LED pin should be 470 pF or less.

REG50

100 kΩ

20 kΩ

LED6

LED5

LED4

LED3

LED2

LED1

Figure 17. To Set LED6 to Unused

1.5 PWM Low Section Detect Function

The Low section of PWM input is counted in V_EN= High status. When PWM Low section reaches 13.1 ms, operation is

regarded as OFF state, and DC/DC output voltage is discharged from the VDISC pin. When the PWM input is turned High,

switching operation is restarted.

1.6 When Setting the LED Current Above 150 mA

LED1 to LED6 pins can be used in bundles.

For example, as shown in the figure on the right, if LED1, LED2,

LED3, LED4, LED5, and LED6 are shorted, 6 times the current set

by the ISET pin can be passed. To short each LED pin, short the

PD pin to the GND pin. Please do not use a function for a Phase

LED6

Delay.

(For Phase Delay function, refer to "1.3 Phase Delay Function".)

LED5

LED4

LED3

LED2

LED1

Figure 18. Application Example When the LED Pin Is Shorted

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Functional Descriptions – continued

2 DC/DC Converters

Detects the lowest voltage among LED1 to LED6 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. A switching signal is output to the OUTL pin through DC/DC Control LOGIC.

2.1 LED Pin Control Voltage V_LEDCTL

2.2 VCC Input Voltage and Series Number of LED

Elements

2.9 Additional Pulse Function

2.10 External Synchronization / Spread Spectrum

Function (SSCG)

2.3 LED Variation and Series Number

2.4 Overvoltage Protection Function OVP

2.5 DC/DC Converter Oscillation Frequency f_OSC

2.6 Setting the low side current detection resistor (R_CSL

2.7 Setting the Coil Constant

2.11 LSDET Function

2.12 VOUT Discharge Function

2.13 Switching Duty Rquired for Applications

2.14 Fluctuation of LED urrent due to ripple voltage

during PWM dimming

)

2.8 Setting the high side current detection resistor

(R_CSH

)

2.1 LED Pin Control Voltage V_LEDCTL

The relation between LED pin control voltage (V_LEDCTL) and R_ISETresistance is shown in the table below.

Relation Between LED Pin Control Voltage (V_LEDCTL

and R_ISET

)

V_LEDCTL

[V]

LED Pin Control Voltage V_LEDCTL

R_ISET[kΩ]

0.83

[V]

50.0

31.2

25.0

20.8

18.0

0.50

0.60

0.72

0.83

0.50

18.0

(138 mA/ch)

31.2

(80 mA/ch)

50.0

(50 mA/ch)

R_ISET[kΩ]

(LED current

setting value)

Figure 19. Relation Between LED Pin Control Voltage (V_LEDCTL) and R_ISET

2.2 VCC Input Voltage and Series Number of LED Elements

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

the input voltage (VCC).

푉퐶퐶 : Input voltage

푉푂푈ꢁ: DC/DC converter output voltage

푉퐶퐶₍

< 푉푂푈ꢁ

(푀ꢀ푁)

)

푀퐴푋

ꢂ

푉푓

: Number of LED series

: LED Vf voltage

< ꢂ × 푉푓

+ 푉

퐿퐸퐷ꢃ푇퐿 (푀ꢀ푁)

(푀ꢀ푁)

푉_{퐿퐸퐷ꢃ푇퐿}: LED control voltage

Select the number of LED series and Vf characteristics that satisfy

the above equation.

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2 DC/DC Converters – continued

2.3 LED Variation and Series Number

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

converter output VOUT. LED pin voltage (LED cathode voltage) in the channels where the Vf voltage of the LED is highest

is lowest, and this is controlled to be V_LEDCTL. Therefore, other LED pin outputs have higher voltages by Vf variation. Select

the number of LED series and Vf characteristics so that the LED short protection does not malfunction.

ꢂ × ꢄ푉푓

₎− 푉푓

₎ꢅ < 푉

₎− 푉

퐿퐸퐷ꢃ푇퐿 (푀퐴푋)

푉

푆퐻ꢆꢇ푇

: LED short protection voltage

(

푀퐴푋

푀ꢀ푁

푆퐻ꢆꢇ푇 푀ꢀ푁

LED short detection voltage can be set as shown in the table below depending on the voltage applied to the SHT pin.

Relationship between SHT pin voltage and LED short protection voltage

SHT pin voltage [V]

LED short protection voltage [V]

0

4.5

5.0

10

0.5

1.0

1.2

12

For example, a voltage can be applied to the SHT pin by dividing the resistance from the REG50 pin. When the SHT pin is

connected to GND, the LED short detection threshold becomes 4.5 V. Please refer to 18.8 SHORT Det (LED Short

Detection) for details.

2.4 Overvoltage Protection Function OVP

Inputs the resistor division of the output voltage VOUT in the

OVP pin.

VOUT

When OVP pin voltage rises to 1.0 V or more, overvoltage

protection is activated. Switching of DC/DC converter is turned

OFF. After that, OVP is released when the OVP pin voltage

drops to 0.95 V.

R_OVP2

OVP

The setting range of R_OVP1is 10 kΩ to 20 kΩ, and it is

recommended to set the OVP pin voltage within the range of

0.6 V to 0.8 V.

Also, the VOUT voltage during OVP detection should not

exceed 45 V, which is the minimum value of overvoltage

protection detect voltage 2 (VDISC pin).

+

ꢀ

-

R_OVP1

1.00 V/0.95 V

Figure 20. OVP Peripheral Circuit Diagram

OVP Pin Voltage Setting Sample

{(

)

}

푉푂푈ꢁ_ꢆꢈ푃= 푅_ꢆꢈ푃ꢉ+ 푅_ꢆꢈ푃ꢊ∕ 푅_ꢆꢈ푃ꢉ× 1.05 < 45

[V]

푉푂푈ꢁ_ꢆꢈ푃

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

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2 DC/DC Converters – continued

2.5 DC/DC Converter Oscillation Frequency f_OSC

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

oscillation frequency of DC/DC converter is generated by the OSC-block. Set the resistor of R_RTreferring to the data and

theoretical formula below.

7

(

)

푓

ꢆ푆ꢃ

= 10 ∕ 푅_ꢇ푇× 훼

[kHz]

푓

: Oscillation frequency of DC/DC converters

ꢆ푆ꢃ

10⁷: Constants determined internally by the circuit

푅_ꢇ푇: RT pin connecting resistor

훼

: Correction factor

For the relation between f_OSCand R_RT, 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.

Example Resistance Value for f_OSCSetting

f_OSCvs R_RT

2400

R_RT[kΩ]

45.0

α

2200

2000

1800

1600

1400

1200

1000

800

1.004

1.000

0.985

0.958

0.888

33.3

20.0

10.0

4.0

600

400

200

4

6

8

10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

_RT[kΩ]

R

Figure 21. f_OSCvs R_RT

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2 DC/DC Converters – continued

2.6 Setting the low side current detection resistor (R_CSL

)

The low side current detection resistor (R_CSL) allows to set the overcurrent protection detection current. Set to satisfy the

following formula.

⁄

퐼_{ꢆꢃ푃퐿(푀ꢀ푁)}= 푉_{ꢆꢃ푃퐿(푀ꢀ푁)}푅_ꢃ푆퐿> 퐼_{퐿(푀퐴푋)}

퐼_{ꢆꢃ푃퐿(푀ꢀ푁)}: Overcurrent protection detection current minimum value

푉_{ꢆꢃ푃퐿(푀ꢀ푁)}: Overcurrent protection detection voltage minimum value (0.27 V)

푅_ꢃ푆퐿

퐼_{퐿(푀퐴푋)}

: CSL pin connection resistance

: Coil peak current maxmum value

2.7 Setting the Coil Constant

To ensure stable operation of DC/DC converters, the following conditions are recommended for the coil inductance value.

9

⁄

푅_ꢇ푇× 푅_ꢃ푆퐿× ꢄ푉푂푈ꢁ_(푀퐴푋)− 푉퐶퐶_{( )}ꢅ ꢋ ≤ 5.1ꢌ × 10

푀ꢀ푁

푅_ꢇ푇

: RT pin connecting resistor

: CSL pin connecting resistor

: DC/DC converter output voltage

: Input voltage

푅_ꢃ푆퐿

푉푂푈ꢁ

푉퐶퐶

ꢋ

: Inductance value

Lowering the value on the left side increases stability, but decreases responsiveness.

Take the dispersion of inductance value into consideration and set it with sufficient margin.

2.8 Setting the high side current detection resistor (R_CSH

)

The high side current detection resistor (R_CSH) allows to set the input overcurrent protection detection current. Set to satisfy

the following formula.

⁄

푅_ꢃ푆퐿

퐼_{ꢆꢃ푃퐻(푀ꢀ푁)}= 푉_{ꢆꢃ푃퐻(푀ꢀ푁)}푅_ꢃ푆퐻> 퐼_{ꢆꢃ푃퐿 푀퐴푋}= 푉

(

)

ꢆꢃ푃퐿(푀퐴푋)

퐼_{ꢆꢃ푃퐻(푀ꢀ푁)}: Input overcurrent protection detection current minimum value

푉_{ꢆꢃ푃퐻(푀ꢀ푁)}: Input overcurrent protection detection voltage minimum value (0.17 V)

푅_ꢃ푆퐻: CSH pin connection resistance

퐼_{ꢆꢃ푃퐿(푀퐴푋)}: Overcurrent protection detection current maxmum value

푉_{ꢆꢃ푃퐿(푀퐴푋)}: Overcurrent protection detection voltage maxmum value (0.33 V)

푅_ꢃ푆퐿

: CSL pin connection resistance

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2 DC/DC Converters – continued

2.9 Additional Pulse 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.

PWM

Additional

Pulse

OUTL

VOUT

VOUT Hold

ILED

Stable LED Current

Figure 22. Pulse Addition Function

The number of switching pulses to be added is set by the resistance value connected to the PLSET pin. As shown in the

figure below, it can connect R_PLSET1, R_PLSET2and set the number of switching pulses to be added by the resistance ratio.

Examples of resistance values are shown in the table below.

Example of Resistance Value

When Setting Additional Pulse Number

Number of

R_PLSET1

R_PLSET2

Additional

Pulses

REG50

PLSET

R_PLSET2

PLSET-GND Shorting

0 Pulse

2 Pulses

4 Pulses

8 Pulses

12 Pulses

DC/DC

Control

LOGIC

Additional Pulse

Output

39 kΩ

100 kΩ

91 kΩ

100 kΩ

39 kΩ

OUTL

R_PLSET1

PLSET-REG50 Shorting

Figure 23. Additional Pulse Number Setting Method

The setting of the number of switching pulses to be added is performed immediately after the EN pin voltage is turned on

and prior to starting. It is not possible to change the setting of the number of switching pulses to be added after startup.

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2 DC/DC Converters – continued

2.10 External Synchronization / Spread Spectrum Function (SSCG)

Three switching modes can be selected according to the voltage input to the SYNC pin. The input to the SYNC pin must

precede the input to the EN pin.

Mode

1

2

V_SYNC

GND or OPEN

V_REG50

DC/DC Switching Frequency

Fixed Frequency Mode Determined by R_RT

Spread Spectrum Mode of the Frequency

Determined by R_RT

3

Pulse Input

Mode to Synchronize with the Frequency Input to

the SYNC Pin

Mode 1: When the SYNC pin is GND or OPEN, the DC/DC converter switches at a fixed frequency determined by the R_RT

.

Mode 2: By shorting the SYNC pin and the REG50 pin, operation in spread spectrum mode (SSCG) is enabled. Noise

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

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

cycle (t_SSCG) is 128 / set oscillation frequency. Note that operating SSCG may change noise levels other than the oscillation

frequency.

VCC

V_EN

V_SYNC

V_PWM

1.0 V

PWM = High Detection

Self Diagnosis

Pre-boost

V_OVP

V_OUTL

Δf = -8 % (Typ)

f_OSC

t_SSCG= 128/f_OSC(Typ)

Figure 24. Spread Spectrum Function Timing Chart

훥푓 : Fluctuation range of the oscillation frequency by SSCG

: DC/DC oscillation frequency

훥푓 = 푓 × 0.08

ꢆ푆ꢃ

푓

ꢆ푆ꢃ

푡_푆푆ꢃ퐺: Modulating period of the oscillation frequency by SSCG

128

푡_푆푆ꢃ퐺

=

푓

ꢆ푆ꢃ

The amount of noise reduction during SSCG S [dB] can be roughly estimated by the following equation.

ꢉ

ｆ＝ f_OSC× 0.08

ꢍ = −10 × 푙표푔 _ꢎꢏ×ꢐ

[dB]

ꢑꢑꢒꢓ

ꢏ

/ꢉꢊꢕ

ꢔꢑꢒ

ꢍ = −10 × 푙표푔 _ꢏ

S[dB]

×ꢖ.ꢖꢕ

ꢔꢑꢒ

ꢍ = 10

[dB]

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

SSCG function cannot be turned ON/OFF during operation.

Frequency

Band

f_OSC× 0.92

f_OSC

Figure 25. Spread Spectrum Function

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2.10 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. Input the clock signal to SYNC pin before the Self Diagnosis is completed. (For Self Diagnosis, refer to "3

Startup Characteristics and Effective Section of Each Protection Function")

Internal oscillation and external synchronization cannot be switched on the way. Operation may become unstable. When

using external synchronization, SSCG cannot be used.

2.11 LSDET Function

LSDET

OFF

LSDET

ON

LSDET

OFF

When the lowest LED pin voltage among the LED pins exceeds

1.5 V (Typ), the DC/DC converter is turned OFF and the COMP

voltage is held.

DC/DC converter resumes switching when the lowest LED pin

voltage drops V_LEDCTLx 1.1 or less.

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 restarting the switching of DC/DC converters just

before returning to normal operation. LSDET function is enabled

only when Duty of the LED current is ON. The following is an

example when LED6 becomes open.

ꢇ

V_OUTL

ꢄ

V_COMP

ꢁ

1.0 V

①

The LED6 pin is open and LED6 pin voltage is 0.3 V (Typ) or

ꢅ

ꢂ

less. (Ⓐ)

V_OVP

DC/DC converter output begins to boost LED6 pin voltage

further. In conjunction with this, OVP pin voltage also rises.

(Ⓑ)

V_LED1

to

V_LED5

②

When OVP pin voltage reaches 1.0 V (Ⓒ) due to the boost

ꢆ

V_LEDCTL

V_LEDCTLx 1.1

of DC/DC converter, the LED open protection is activated.

When the LED open protection is activated, the LED6 pin

that was open is pulled up to REG50 pin voltage V_REG50

REG50 Pull Up (V_REG50

)

inside the IC. (Ⓓ)

LSDET function operates because LED6 pin voltage, which

is the lowest LED pin voltage among the LED pins, exceeds

ꢃ

V_LED6

V_LEDCTL

1.5 V (Typ)

0.3 V (Typ)

ꢀ

1.5 V (Typ). (Ⓓ)

LSDET function turns OFF DC/DC converters and holds

LED6

Open

LED6

Open

Detection

COMP voltage. (Ⓔ)

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

OVP pin voltage also drops. (Ⓕ)

I_LED1

to

I_LED5

③

④

When the lowest LED pin voltage is V_LEDCTLx 1.1 (Typ) or

I_LED6

less (Ⓖ) the DC/DC converters resume switching. (Ⓗ)

Figure 26. LSDET Function When LEDs Are Open

2.12 VOUT Discharge Function

The LEDs may flicker if activated with charges remaining on VOUT. Therefore, discharging of VOUT is required at startup.

However, discharging of the charge may take a long time only by the discharge path such as the resistor for OVP setting.

Therefore, an output voltage discharging circuit (VOUT discharge function) is provided in this model. When DC/DC circuit

is OFF (when EN pin voltage falls or PWM Low section is detected), residual charges in the output are discharged. The

discharge time t_DISCis expressed by the following equation.

푡_퐷ꢀ푆ꢃ= 3 × 퐶_ꢆꢗ푇× 푉푂푈ꢁ [s]

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2 DC/DC converters – continued

2.13 Switching Duty Required for Applications

As an application of DC/DC converters, the switching duty required for stable operation can be roughly estimated by the

following equations.

(

) (

)

ꢍ푊ꢘ푈ꢁ푌 = 푉_ꢆꢗ푇+ 푉푓 − 푉퐶퐶 / 푉_ꢆꢗ푇+ 푉푓 − 푉ꢘ_푀ꢊ

퐷ꢉ

ꢍ푊ꢘ푈ꢁ푌 : Required switching Duty

푉_ꢆꢗ푇

: DC/DC converter output voltage

: Vf voltage of the boosting diode (D1)

: Input voltage

푉푓

퐷ꢉ

푉퐶퐶

푉ꢘ_푀ꢊ

: Drain voltage when FET (M2) for boosting is ON

The above values are approximate values. The switching Duty actually required depends on the characteristics and

operating conditions of the application components. Finally, check the actual operation.

2.14 Fluctuation of LED current due to ripple voltage during PWM dimming

During PWM dimming, the LED current does not flow and the LED pin voltage (V_LED) becomes high in the PWM = Low

section, and the V_LEDis controlled by the V_LEDCTLin the PWM = High section.Depending on the settings of external

components such as the LED current setting and the capacity of the output capacitor, the V_LEDmay undershoot at the

start of PWM. Due to this undershoot, the LED current may drop momentarily as shown in the figure below. When the

LED current setting value of each CH is 65 mA or more, it is recommended that the undershoot amount (ΔVdrop) of V_LED

at PWM = High is 50 mV or less. However, even if the LED current drops momentarily due to undershoot, the LED may

not appear to flicker. Be sure to evaluate on the actual board and check from a visual point of view.

PWM

V_LED

LED pin

Control voltage

(V_LEDCTL

)

undershoot

(ΔVdrop)

50 mV

I_LED

V_LEDand I_LEDtiming chart during PWM dimming

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Functional Descriptions - continued

3 Startup Characteristics and Effective Section of Each Protection Function

3.1 When PWM Duty Is 100 %

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

①

②

Power ON: Input EN voltage after the VCC voltage is input.

Self Diagnosis: Determines the channels to be used, determines whether or not to use Phase Delay, sets the number

of additional pulses, and sets PWM/DC dimming, etc. Self Diagnosis is completed after 13.1 ms (Typ), and the

diagnostic status is latched.

③

PWM signal detection: When PWM = High has elapsed 13.1 ms, it recognizes that PWM = 100 % and begins the

startup.

Pre-boost^{(Note 1)}: Outputs switching until the OVP pin voltage reaches 1.0 V and boosting is performed.

Stable operation transition section: DC/DC switching is turned OFF. The output voltage of DC/DC converter drops

according to the LED current.

④

⑤

⑥

Stable state: When LED voltage (the lowest voltage in LED1 to LED6) drops to LED control voltage x 1.1, DC/DC

converter switches again.

(Note 1) Because a higher switching Duty is required than stable state, Pre-boost may not be completed depending on operating conditions and component

conditions. Contact us for details.

VCC

ꢌ

V_EN

3.1 V (Typ)

(UVLO Release)

V_REG50

V_DIMSEL

0 V (PWM DImming Only)

V_PWM

ꢀꢍ Stable

Operation

Transition

Section

ꢊ PWM Signal

Detection

13.1 ms

ꢉ Pre-boost

ꢋ Stable State

ꢈ Self Diagnosis

13.1 ms (Typ)

・Determination of CH

to use

・Setting phase delay

・Setting the number

of additional pulse

・PWM/DC dimming

setting

V_OVP

V_OUTL

I_LED

1.0 V

・OVP pin fault

detection

LED Setting Current Output Section

LED Control Voltage × 1.1

V_LED

LED Control Voltage

During Self Diagnosis

FAIL1, FAIL2 are Low

V_FAIL1

V_FAIL2

DC/DC Converter Operating Section

Current Driver Operating Section

Under Voltage Lockout (UVLO) Effective when EN = High

Thermal ShutDown (TSD) Effective when EN = High

Thermal Warning (TW) 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 released

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

ISET-GND Short Protection / FAIL Flag Effective when pre-boost starts

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

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

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

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3 Startup Characteristics and Effective Section of Each Protection Function – continued

3.2 When Using only PWM Dimming

The timing chart at startup and the effective section of each protection function when only PWM dimming is used are shown

in the figure below.

①

②

Power ON: Input EN voltage after the VCC voltage is input.

Self Diagnosis: Determines the channels to be used, determines whether or not to use Phase Delay, sets the number

of additional pulses, and sets PWM/DC dimming, etc. Self Diagnosis is completed after 13.1 ms (Typ), and the

diagnostic status is latched.

③

④

PWM signal detection: Begins the startup at the first rising edge of PWM.

Pre-boost^{(Note 1)}: Regardless of On Duty of PWM, switching is output until OVP pin voltage reaches 1.0 V, and boosting

is performed.

⑤

⑥

Stable operation transition section: DC/DC switching is turned OFF. The output voltage of DC/DC converter drops

according to the LED current.

Stable state: When LED voltage (the lowest voltage in LED1 to LED6) drops to LED control voltage x 1.1, DC/DC

converter switches again.

(Note 1) Because a higher switching Duty is required than stable state, Pre-boost may not be completed depending on operating conditions and component

conditions. Contact us for details.

VCC

ꢌ

V_EN

3.1 V (Typ)

(UVLO Release)

V_REG50

V_DIMSEL

0 V (PWM Dimming Only)

V_PWM

ꢀꢍ Stable Operation Transition Section

ꢉ Pre-boost

ꢋ Stable State

ꢈ Self Diagnosis

ꢊ PWM

Signal

Detection

13.1 ms (Typ)

・Determination of CH

to use

・Setting phase delay

・Setting the number

of additional pulse

・PWM/DC dimming

setting

V_OVP

V_OUTL

I_LED

1.0 V

・OVP pin fault detection