FAN7346MX - Fairchild Semiconductor Corporation

May 2011

FAN7346 • 1.0.0

FAN7346 — 4-Channel LED Current Balance Controller

FAN7346

4-Channel LED Current Balance Controller

Features

 Linear Balance Control for 4-Channel LED Arrays

 Wide LED String Voltage Range:  100V

 Wide VCC Voltage: 10.5V to 35V

 External Linear Regulation Switch: MOSFET or BJT

 Internal Voltage Regulator for Feedback

 Monitoring Drain-Source Voltage of External Switch

 Precision Current Accuracy Trimmed to 1.5%

 Supports External PWM Dimming - Positive

 Supports Wide Dimming Ratio: 0.5%~100%

 Adaptive Linear Regulation Method

 Generate Integrated Feedback Signal for Primary

Controller (Current Feedback + PWM Dimming)

 High Efficiency by Primary Side Direct Feedback

 Thermal Shutdown (Auto-Recovery)

 Over-Voltage Regulation

 Channel Individual Open-LED Protection

 Channel Individual Short-LED Protection

 Channel Individual Over-Current Protection

 Error Flag Output

 28-Pin SOIC

Applications

 LED BLU for LCD TV

 LED BLU for LCD Monitor

 LED Lighting

Description

The FAN7346 is an LED current-balance controller that

controls 4-LED arrays to maintain equal LED current.

The FAN7346 has a high withstanding voltage, so is

suitable for edge-type LED BLU and LED Lighting. To

minimize components between primary to secondary, the

FAN7346 generates a new integrated feedback signal.

The FAN7346 provides various protections, such as

over-voltage regulation, open-LED protection, thermal

protection, and drain-source voltage protection of

regulating switch (the FAN7346 monitors all LED arrays

drain-source voltage for protection). To increase system

reliability, FAN7346 applies individual string protection.

Because FAN7346 integrates so many functions it

reduces overall BOM costs.

LED brightness can be linearly varied up to LED current

by applying an external Pulse Width Modulated (PWM)

signal to the PWM pin.

The FAN7346 is available in a 28-SOIC package.

Ordering Information

Part Number Operating

Temperature Package Packing Method

FAN7346M -40 to +125°C 28-Lead, Small-Outline Integrated Circuit (SOIC) Rail

FAN7346MX Tape & Reel

FAN7346 • 1.0.0 2

FAN7346 — 4-Channel LED Current Balance Controller

Block Diagram

Figure 1. Internal Block Diagram

FAN7346 • 1.0.0 3

FAN7346 — 4-Channel LED Current Balance Controller

Pin Configuration

Figure 2. Package Diagram

Pin Definitions

Pin # Name Description

1 OVR This pin is input for over-voltage regulation.

2 FB

This pin is for feedback of minimum drain voltage of external current regulation switch. This

pin is externally connected to the cathode of the feedback photo-coupler.

3 CMP This pin is for compensation of the minimum channel voltage feedback.

4 VMIN Synchronous signal of channel drain-voltage. If multiple controllers are operated, this pin

must be tied together. In single operation, this pin must be open.

5 FO This pin is fault output. In case of OLP, SLP, and OCP; this pin is connected to ground.

6 PWM4 PWM dimming signal input pin of channel 4.

7 PWM3 PWM dimming signal input pin of channel 3.

8 PWM2 PWM dimming signal input pin of channel 2.

9 PWM1 PWM dimming signal input pin of channel 1.

10 ENA Enable input.

11 ADIM This pin is for the reference voltage of the LED current feedback voltage.

12 SLPR This pin is for setting the reference of channel over-voltage protection (short-LED protection).

13 REF This pin is the reference output. Voltage is 5V; current capability is 3mA.

14 VCC This pin is the supply voltage of the controller.

15 FB4 This pin is for current sensing feedback of channel 4.

16 VDD Internal gate driver power supply voltage. A large capacitor (1µF~2µF) must be connected

from this pin to ground.

17 OUT4 This pin is for gate signal to the external balance FET of channel 4.

18 CH4 This pin is for drain voltage of the external balance FET of channel 4.

19 FB3 This pin is for current sensing feedback of channel 3.

20 OUT3 This pin is for gate signal to the external balance FET of channel 3.

21 CH3 This pin is for drain voltage of the external balance FET of channel 3.

22 FB2 This pin is for current sensing feedback of channel 2.

23 OUT2 This pin is for gate signal to the external balance FET of channel 2.

24 CH2 This pin is for drain voltage of the external balance FET of channel 2.

25 FB1 This pin is for current sensing feedback of channel 1.

26 OUT1 This pin is for gate signal to the external balance FET of channel 1.

27 CH1 This pin is for drain voltage of the external balance FET of channel 1.

28 GND This pin is the ground.

FAN7346 • 1.0.0 4

FAN7346 — 4-Channel LED Current Balance Controller

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be

operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In

addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The

absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

VIN IC Supply Voltage 10.5 35.0 V

TA Operating Temperature Range -40 +125 C

TJ Operating Junction Temperature +150 C

TSTG Storage Temperature Range -65 +150 C

θJA Thermal Resistance Junction-Air(1,2) 70

C/W

PD Power Dissipation 1.4 W

Notes:

1. Thermal resistance test board. Size: 76.2mm x 114.3mm x 1.6mm (1S0P); JEDEC standard: JESD51-2, JESD51-3.

2. Assume no ambient airflow.

Pin Breakdown Voltage

Pin # Name Value Unit Pin # Name Value Unit

1 OVR 6

15 FB4 6

2 FB 6 16 VDD 17

3 CMP 6 17 OUT4 17

4 VMIN 6 18 CH4 100

5 FO 6 19 FB3 6

6 PWM4 6 20 OUT3 17

7 PWM3 6 21 CH3 100

8 PWM2 6 22 FB2 6

9 PWM1 6 23 OUT2 17

10 ENA 6 24 CH2 100

11 ADIM 6 25 FB1 6

12 SLPR 6 26 OUT1 17

13 REF 6 27 CH1 100

14 VCC 35 28 GND

FAN7346 • 1.0.0 5

FAN7346 — 4-Channel LED Current Balance Controller

Electrical Characteristics

For typical values; TA = 25°C, VIN = 12V, and -25°C  TA  85°C, unless otherwise specified. Specifications to -40°C ~

125°C are guaranteed by design based on final characterization results.

Symbol Parameter Condition Min. Typ. Max. Unit

Under-Voltage Lockout Section (UVLO)

Vth Start Threshold Voltage 8.5 9.5 10.5 V

Vthhys Start Threshold Voltage Hysteresis 0.5 1.0 1.5 V

Ist Startup Current VIN=8V 100 300 µA

Iop Operating Supply Current VIN=12V, Not Switching 1 3 mA

ON/OFF Section

Von On-State Input Voltage 1.4 5.0 V

Voff Off-Stage Input Voltage 0.7 V

RENA Pull-Down Resistor 130 200 270 kΩ

Reference Section (Recommend 1µF X7R Capacitor)

VREF 5V Regulation Voltage IREF=0mA 4.9 5.0 5.1 V

VR-LINE 5V Line Regulation 10  VIN  35V 50 mV

VR-LOAD 5V Load Regulation 0  IREF  3mA 50 mV

VDD 8.5V Regulation Voltage VIN=12V 8.0 8.5 9.0 V

LED Current Section

VFBX CH LED Current Reference Voltage VADIM=2V 194 200 206 mV

VLREF LED Current Reference Voltage 0.5V  VADIM  4V VADIM

/10 V

VADIM-CLAMPH ADIM Voltage HIGH Clamping Voltage VIN=12V 3.84 4.00 4.16 V

VADIM-CLAMPL ADIM Voltage LOW Clamping Voltage VIN=12V 0.45 0.50 0.55

BCH Current Balance Between Channels VADIM=2V -1.5 1.5 %

Headroom Voltage Feedback Section

VFBR Feedback Reference Voltage 0.95 1.00 1.05 V

Ileak Channel Leakage Current PWM ON, VCH=1V 0 100 µA

PWM OFF, VCH=30V 0 2 µA

AV Open-Loop Gain(3) V

VMIN=1V 65 dB

Gm Error Amplifier Transconductance VVMIN=1.5V 140 180 220 µmho

lsin Output Sink Current VVMIN=0V 70 120 170 µA

lsur Output Source Current VVMIN=2V 70 120 170 µA

Continued on the following page…

FAN7346 • 1.0.0 6

FAN7346 — 4-Channel LED Current Balance Controller

Electrical Characteristics (Continued)

For typical values; TA = 25°C, VIN = 12V, and -25°C  TA  85°C, unless otherwise specified. Specifications to -40°C ~

125°C are guaranteed by design based on final characterization results.

Symbol Parameter Condition Min. Typ. Max. Unit

PWM Dimming Section

Vbdim(ON) PWM Dimming On Voltage 2 5 V

Vbdim(Off) PWM Dimming Off Voltage 0 0.8 V

fbdim PWM Dim Input Frequency Range(3) On Duty Ratio=1% 100 500 Hz

tbdimR PWM Dim On Rising Time(3) Ext. Switch Qg=4.3nC 400 ns

tbdimF PWM Dim Off Falling Time(3) Ext. Switch Qg=4.3nC 150 ns

Soft-Start Section

tSS Soft-Start Time(3) VOVR=1V, ILED: 0 to

Maximum 10 ms

Protection Section

VTH,OVR OVR Threshold Voltage 1.35 1.42 1.49 V

VTH,OCP OCP Threshold Voltage 0.95 1.00 1.05 V

TOCP OCP Shutdown Time(3) 10 µs

VTH,SLP SLP Threshold Voltage VSLPR=1V 9.5 10.0 10.5 V

TD,SLP SLP Delay(3) 20 µs

TD,OLP OLP Delay(3) 20 µs

VTH,OLP OLP Threshold Voltage 0.27 0.30 0.33 V

TTRIP Internal Thermal Protection

Threshold(3) 150 °C

TTYH Internal Thermal Protection

Hysteresis(3) 25 °C

Output Section

VGH NMOS Gate High Voltage VIN=12V 8.0 8.5 9.0 V

VGL NMOS Gate Low Voltage VIN=12V 0 V

VG,UVLO NMOS Gate Voltage with UVLO

Activated VIN=7V 0.3 V

IG,SOURCE NMOS Gate Drive Source Current VIN=12V 50 150 250 mA

IG,SINK NMOS Gate Drive Sink Current VIN=12V 300 500 700 mA

Note:

3. These Parameters, although guaranteed, are not 100% tested in production.

FAN7346 • 1.0.0 7

FAN7346 — 4-Channel LED Current Balance Controller

Typical Performance Characteristics

Figure 3. Start Threshold Voltage vs. Temperature Figure 4. Start Threshold Voltage Hysteresis

vs. Temperature

Figure 5. Startup Current vs. Temperature Figure 6. Operating Current vs. Temperature

Figure 7. Enable Threshold Voltage vs. Temperature Figure 8. Pull-Down Resistor vs. Temperature

8.5

9.5

10.5

-50 -25 0 25 50 75 100 125

Vth [V]

Temperature [Ԩ]

0.4

0.6

0.8

1.2

1.4

1.6

-50 -25 0 25 50 75 100 125

Vthhys [V]

Temperature [Ԩ]

100

150

200

250

300

350

-50 -25 0 25 50 75 100 125

Ist [µA]

Temperature [Ԩ]

0.5

1.5

2.5

3.5

-50 -25 0 25 50 75 100 125

Iop [mA]

Temperature [Ԩ]

0.6

0.7

0.8

0.9

1.1

1.2

1.3

1.4

1.5

-50 -25 0 25 50 75 100 125

Vonth [V]

Temperature [Ԩ]

100

150

200

250

300

-50 -25 0 25 50 75 100 125

Rena [KΩ]

Temperature [Ԩ]

FAN7346 • 1.0.0 8

FAN7346 — 4-Channel LED Current Balance Controller

Typical Performance Characteristics (Continued)

Figure 9. 5V Regulation Voltage vs. Temperature Figure 10. 8.5V Regulation Voltage vs. Temperature

Figure 11. Offset of CH LED Current Reference Voltage

vs. Temperature

Figure 12. ADIM HIGH Clamping Voltage

vs. Temperature

Figure 13. ADIM LOW Clamping Voltage

vs. Temperature

Figure 14. Current Balance Between Channels

vs. Temperature

4.85

4.9

4.95

5.05

5.1

5.15

-50 -25 0 25 50 75 100 125

VREF [V]

Temperature [Ԩ]

7.8

8.2

8.4

8.6

8.8

9.2

-50 -25 0 25 50 75 100 125

VDD [V]

Temperature [Ԩ]

-8

-6

-4

-2

-50 -25 0 25 50 75 100 125

Vofs [mV]

Temperature [Ԩ]

3.82

3.86

3.9

3.94

3.98

4.02

4.06

4.1

4.14

4.18

-50-25 0 255075100125

VADIM-CLAMPH [V]

Temperature [Ԩ]

0.43

0.45

0.47

0.49

0.51

0.53

0.55

0.57

-50 -25 0 25 50 75 100 125

VADIM-CLAMPL [V]

Temperature [Ԩ]

-2

-1.5

-1

-0.5

0.5

1.5

-50 -25 0 25 50 75 100 125

BCH [%]

Temperature [Ԩ]

FAN7346 • 1.0.0 9

FAN7346 — 4-Channel LED Current Balance Controller

Typical Performance Characteristics (Continued)

Figure 15. Feedback Reference Voltage

vs. Temperature

Figure 16. Error Amplifier Transconductance

vs. Temperature

Figure 17. Error Amplifier Output Sink Current vs.

Temperature

Figure 18. Error Amplifier Output Source current vs.

Temperature

Figure 19. PWM Dimming On Threshold Voltage

vs. Temperature

Figure 20. OVR Threshold Voltage vs. Temperature

0.94

0.96

0.98

1.02

1.04

1.06

-50 -25 0 25 50 75 100 125

VFBR [V]

Temperature [Ԩ]

120

140

160

180

200

220

240

-50 -25 0 25 50 75 100 125

Gm[µMho]

Temperature [Ԩ]

100

120

140

160

180

-50 -25 0 25 50 75 100 125

ISIN [µA]

Temperature [Ԩ]

100

120

140

160

180

-50 -25 0 25 50 75 100 125

ISUR [µA]

Temperature [Ԩ]

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

-50 -25 0 25 50 75 100 125

Vbdim(th) [V]

Temperature, [Ԩ]

1.34

1.36

1.38

1.4

1.42

1.44

1.46

1.48

1.5

-50-25 0 255075100125

VTH,OVR [V]

Temperature, [Ԩ]

FAN7346 • 1.0.0 10

FAN7346 — 4-Channel LED Current Balance Controller

Typical Performance Characteristics (Continued)

Figure 21. OCP Threshold Voltage vs. Temperature Figure 22. SLP Threshold Voltage vs. Temperature

Figure 23. OLP Threshold Voltage vs. Temperature Figure 24. NMOS Gate High Voltage vs. Temperature

Figure 25. NMOS Gate Drive Source Current

vs. Temperature

Figure 26. NMOS Gate Drive Sink Current

vs. Temperature

0.9

0.95

1.05

1.1

-50 -25 0 25 50 75 100 125

VTH,OCP [V]

Temperature [Ԩ]

9.4

9.6

9.8

10.2

10.4

10.6

-50 -25 0 25 50 75 100 125

VTH,SLP [V]

Temperature [Ԩ]

0.26

0.27

0.28

0.29

0.3

0.31

0.32

0.33

0.34

-50 -25 0 25 50 75 100 125

VTH,OLP [V]

Temperature [Ԩ]

7.8

8.2

8.4

8.6

8.8

9.2

-50 -25 0 25 50 75 100 125

VGH [V]

Temperature [Ԩ]

100

150

200

250

-50 -25 0 25 50 75 100 125

IG,SOURCE [mA]

Temperature [Ԩ]

200

300

400

500

600

700

-50 -25 0 25 50 75 100 125

IG,SINK [mA]

Temperature [Ԩ]

FAN7346 • 1.0.0 11

FAN7346 — 4-Channel LED Current Balance Controller

Functional Description

The FAN7346 is a high-efficiency 4-channel LED driver.

It can drive a 4-channel LED string with four external

balance switches. It provides an integrated feedback for

a DC-DC controller on the secondary side or on the

flyback / LLC controller of the primary side.

Due to the high withstanding voltage of the sensing pin

for drain voltage of external switch, the FAN7346 can be

used in high-voltage LED string operation without any

clamping circuit. Both MOSFET and transistor can be

used as external balance switch, so the FAN7346 can

drive a high-current LED string.

For four-string operation, the FAN7346 supports four

individual PWM signal input pins. The FAN7346 can be

operated by parallel connection mode.

For a primary-side direct-power control system, the

FAN7346 supports an advanced power sequence and

soft-start timing. LED driving voltage can be set before

LED ignition for a reliable LED backlight ignition.

The FAN7346 supports various and programmable

protections; Short-LED Protection (SLP), Open-LED

Protection (OLP), Over-Current Protection (OCP), and

Over-Voltage Regulation (OVR). Except OCP, all

protection are auto-recovery / auto-restart. Except OVR,

all protections are channel-individual protection. In case

of SLP, OLP and OCP; even if some strings are in

protection condition, other strings continues to operating

for higher system reliability.

Figure 27 shows the work-flow of startup sequence.

1. Startup

When VCC voltage is higher than UVLO threshold

voltage, internal 5V regulation output is operated. At the

same time, feedback starts to control OVR voltage as 1V.

If OVR voltage is lower than 1V, feedback is pulled up. If

OVR voltage is higher than 1V, feedback is pulled down.

After enable is applied, the FAN7346 begins soft-start

procedure. The FAN7346 checks if OVR voltage is

higher than 0.9V. If OVR voltage is lower than 0.9V, soft-

start function is not started. If OVR voltage is higher than

0.9V, the FAN7346 starts LED current balance and soft-

start. The LED current of each string is increased

gradually for 10ms, which is fixed soft-start timing. During

soft-start timing, SLP and OLP are disabled.

Figure 27. Startup Sequence

2. Feedback

After soft-start, the FAN7346 starts feedback drain-

voltage of external balance switch.

Drain voltage of each channel is sensed on the CHx pin.

CHx means any of the CH1 / CH2 / CH3 / CH4 pins.

Minimum drain voltage is selected between four CHx

voltages. The FAN7346 feeds back drain voltage to

control minimum drain voltage at 1V.

If minimum drain voltage is higher than 1V, FB is pulled

LOW. If minimum drain voltage is lower than 1V, FB is

pulled HIGH.

Feedback response can be controlled by adding a

resistor and capacitor to the CMP pin.

3. Analog Dimming

In the FAN7346, LED current can be modified by

changing ADIM voltage.

LED current is controlled by the FBx pin voltage. FBx

means any of the FB1 / FB2 / FB3 / FB4 pins. External

current balance switch is operating in the saturation

region to control LED current. Sensed voltage on the FBx

pin is compared with internal reference voltage and the

controller supplies a gate / base signal for the external

current balance switch.

Internal reference voltage is decided by ADIM voltage.

The formula for LED current calculation is:

SENSE

ADIM

LEDR

I

 (1)

ADIM voltage is clamped internally from 0.5V to 4V. If

ADIM voltage is lower than 0.5V, it is clamped as 0.5V. If

ADIM voltage is higher than 4V, it is clamped as 4V.

FAN7346 • 1.0.0 12

FAN7346 — 4-Channel LED Current Balance Controller

4. PWM Dimming

The FAN7346 has four PWM dimming signal pins. Each

PWM dimming pin controls an LED string.

If PWM dimming voltage is higher than 2V, an external

balance switch is turned on and conducts constant

current operation. If PWM dimming voltage is lower than

0.8V, an external balance switch is turned off and blocks

LED current.

During PWM dimming off, open-LED protection and

short-LED protection is disabled.

CHx drain voltage is sampled during PWM dimming on

and held during PWM dimming off to maintain drain

voltage regardless of dimming on/off signal.

5. Short-LED Protection (SLP)

To sense a short-LED condition, the FAN7346 uses the

drain voltage of external balance switch. If some LEDs

are shorted, its LED forward voltage is lower than other

LED strings, so the drain voltage of the external balance

switch is higher than other drain voltage.

SLP threshold voltage can be programmed by SLPR

(Short-LED Protection Reference) voltage. Internal SLP

threshold voltage is calculated as:

SLPR

SLP

︳

V (2)

Minimum SLP threshold voltage is 0V and maximum SLP

threshold voltage is 45V.

SLP is a channel-individual protection. If any string is in

SLP condition, the SLP strings is turned off and other

string operate normally.

If the sensed-drain voltage (CHx voltage) is higher than

the programmed threshold voltage for 20µs, CHx goes into

short-LED protection, which forces the corresponding

channel to turn off. To increase reliability, the SLP channel

is restarted in the next PWM dimming signal rising timing.

After restarting, the FAN7346 checks the drain voltage. If

the drain voltage is higher than the SLP threshold voltage

for 20µs, the switch is turned off. If drain voltage is lower,

the channel is restored to normal operation. Shorted LED

channel operation is minimum duty PWM dimming with a

20µs dimming on period. During 100% full duty PWM

dimming, auto restart is not activated.

Figure 28 shows the SLP operation. As soon as

SLPR*10 (blue line) is lower than CHx voltage, CHx is

forced into minimum duty dimming operation.

Figure 28. Short-LED Protection Operation

6. Open LED Protection (OLP)

To sensing open-LED condition, the FAN7346 use the

drain voltage of an external balance switch. If an LED

string is open, the drain voltage of external balance

switch is grounded, and the FAN7346 can detect open-

LED condition. OLP threshold voltage is 0.3V.

If CHx voltage is lower than 0.3V for 20µs, its drain-

voltage feedback is pulled up to 5V. This means the open

LED string is eliminated from minimum drain voltage

feedback loop. Without OLP, if minimum drain voltage is

0V, drain voltage feedback forces the FB signal to

increase output power. This can cause SLP or thermal

stress in other channels.

OLP is an auto-recovery protection. As soon as drain

voltage is higher than 0.3V, OLP is finished and the drain

voltage feedback system is restored.

Figure 29 shows the OLP operation. Before open CH2,

CH2 is the headroom channel. (CH2 drain voltage is

minimum voltage – 1V.) As soon as open CH2, its drain

voltage is 0V, OLP is activated, and CH2 is removed

from headroom feedback control loop. CH1 is selected

as minimum drain voltage channel, so its drain voltage is

controlled as 1V. Reconnecting CH2 string, restores

normal operation.

Figure 29. Open-LED Protection Operation

CHx Volta

LED

Current

Out

SLPR

CH2

LED

urrent

Out

CH1 Drain Volta

CH2 Drain Volta

Normal SLP

CH2 Open

FAN7346 • 1.0.0 13

FAN7346 — 4-Channel LED Current Balance Controller

7. Over-Voltage Regulation (OVR)

To prevent LED driving voltage from exceeding the

withstanding voltage of system components, the

FAN7346 controls LED driving voltage with OVR pin

voltage. The FAN7346 senses output LED driving

voltage through the OVR pin voltage. Resistor divided

output voltage is applied to the OVR pin voltage.

In FAN7346, OVR voltage uses two kinds of feedback

and control: and regulating output voltage during enable

off and clamping output voltage during enable on.

When ENA pin is LOW, the FAN7346 controls FB voltage

to maintain OVR voltage as 1.0V. Through this output

voltage control during ENA off, the FAN7346 reaches

adequate LED driving voltage before turning ENA on.

After ENA pin is HIGH, OVR pin voltage is used for over-

voltage regulation. If OVR pin voltage is lower than

1.42V, the FB pin voltage follows headroom control to

maintain minimum voltage of drain voltages as 1V. If

OVR pin voltage is higher than 1.42V, the FAN7346

controls FB (FB is pulled LOW). Through feedback

regulation, OVR pin voltage cannot exceed 1.42V.

8. Over-Current Protection (OCP)

Through over-current protection, the FAN7346 can

protect external balance switches from shorted over-

current damage. To sense over-current condition, the

FAN7346 monitors FBx (FB1~FB4) pin voltage.

If FBx voltage is higher than 1V for 20µs, CHx is

considered an over-current condition. After sensing OCP

condition, CHx dimming switch is turned off.

OCP is channel individual and latched protection. If one

channel is in OCP condition, other channels keep

operating. OCP channel is restarted after UVOL is reset.

9. Error Flag (FO)

To make error flag signal, the FAN7346 uses the FO pin.

FO pin is open-drain type.

During normal operation, the FO pin is open. If using an

external pull-up resistor, this signal is HIGH.

If used OLP / OCP / SLP protection, the FO pin is

connected to ground. If using an external pull-up resistor,

this signal is LOW.

If a single channel is in protection condition, error-flag

signal is detected. Only if all channels are operating

normally is the FO pin pulled HIGH.

FAN7346 • 1.0.0 14

FAN7346 — 4-Channel LED Current Balance Controller

Short Lamp Protection

Figure 30. Block Diagram of Short LED Protection

Figure 31. Timing Diagram of Short LED Protection

FAN7346 • 1.0.0 15

FAN7346 — 4-Channel LED Current Balance Controller

Typical Application Circuit (Backlight)

Application Device Input Voltage Range LED String

32~46 Inch LED TV FAN7346 380V 8-String / 90V / 100mA

Figure 32. LCD Backlight Driver

CN5

CON3

FQT4N2 5

10k

FAN7621

16-SOIC

1.HVcc

2.CTR

3.HO

6.CON

8.RT

9.CS

10.SG

12.LVcc

14.LO

16.PG

C34

open

C22

FQT4N25

R107

3.3R

R105

4.7k

R10

100k

R14

22R

R18

open

R114

10k

C202

100uF/200V

FQT4N25

C11

FQT4N25

R55

C112

680pF/50V

R12

open

10k

U2A

PC817A

1 2

D102

LMBD914

R13

open

D212

FEP16JT

100k

R720R

2N2222

R53

3.9R

R58

R57

3.9R

FQT4 N25

C10

12k

C37

open

C19

open

R32

R26100k

CN6

CON3

R17

R37

FQT4N2 5

R28 open

D211

FEP16 JT

C109

25V/47uF

R38

R25

10k

R710R

C106

2A224K

D101

UF4007

ZD101

6.8V/1N4736

FAN7346

IC3

FAN7346

28-SOIC

OVR

CMP

VMIN

PWM4

PWM3

PWM2 CH3

FB2

OUT2

CH2

FB1

OUT1

CH1

GND

PWM1

ENA

ADIM

SLPR

REF

VCC

OUT3

FB3

CH4

OUT4

VDD

FB4

C103

100pF/50V

R110

R109

10k

R108

3.3R

FQT4N25

R23

open

C33

open

CN3

CON10

M101

FDD5N50F

R104

910R

R24

open

R31

FUS E

R107

1.8k

ZD1 02

open

SOD-123

10n

R113

390k

U2B

PC817A

4 3

C31

open

TM103

EER39HS-16

C36

open

R112

10k

R55

3.9R

R54

3.9R

R11

10k

C105

0.33uF/25V

C16

R52

3.9R

R106

10R

C38

open

R101

0.1R/1W

FQT4N25

R51

3.9R

2N2907

open

C107

16V / 33uF

R109

D101

LMBD914

C13

22uF/50V

C35

open

10n

M102

FDD5N50F

C108

12nF/100V

R56

C20

C102

MPE630V223J

R110

10k

R27

10k

C14

C12

R102

R57

R56

3.9R

10n

R58

3.9R

C101

220uF/450V

FAN7346

IC2

FAN7346

28-SOIC

OVR

CMP

VMIN

PWM4

PWM3

PWM2 CH3

FB2

OUT2

CH2

FB1

OUT1

CH1

GND

PWM1

ENA

ADIM

SLPR

REF

VCC

OUT3

FB3

CH4

OUT4

VDD

FB4

C32

open

R19

CN6

CON10

R111

47k

PWM3

PWM4

PWM1PWM2

ENA

VCC2

ENAPW M5

PWM8

V CC2

PWM6PWM7

VCC1

PFC_OUT(380Vdc)

PWM2

PWM1

PWM4

PWM3

PWM6

PWM5

PWM8

PWM7

REF1

REF2

REF1

FSFR2100

C201

100uF/200V

C203

100uF/200V

VC C 1

FAN7346 • 1.0.0 16

FAN7346 — 4-Channel LED Current Balance Controller

Typical Application Circuit (Lighting) (Continued)

Application Device Input Voltage Range LED String

LED Lighting FAN7346 380V 4-String

SG PG

C116

LVCC

VCTR

HVCC

VDL

FLS-XS

Series

R203

D203

RS12

CS14

VCC

OVR

VDD

REF

ENA

SLPR

ADIM

VMIN

CMP

PWM4

PWM3

PWM2

PWM1

GND

CH1

OUT1

FB1

CH2

OUT2

FB2

CH3

OUT3

FB3

CH4

OUT4

FB4

VAUX

RS19

CS15

RS27

RS14

CS12 CS16

RS15

RS17

RS18

RS22

RS13

CS9

CS8

C205C206

C204

C201

D202

D201

RS8

CS6 RS10

RS32

RS31

RS23

RS30

RS16

RS29

RS11

CS7

CS10

CS11

CS13

CS17

Fault

D107

R128 C115

R130

R131 R132

Q104

Q103

U201

D204

C123

C124

D109

R133

PC101

R136 R135 R134

C114

C125

C127

R126

R127

R202

C202 C203 VLED

Q1 Q2 Q3 Q4

U102

RS20

RS28

RS21

RS24

R129

R201

C126

TM2

R123

PC101

RS25

IC1

Figure 33. LED Lighting Driver

FAN7346 • 1.0.0 17

FAN7346 — 4-Channel LED Current Balance Controller

Typical Application Circuit (Continued)

Figure 34. Multiple Controller Driving

FAN7346 • 1.0.0 18

FAN7346 — 4-Channel LED Current Balance Controller

Physical Dimensions

Figure 35. 28-Lead, Small-Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300-Inch, Wide Body

Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner

without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or

obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions,

specifically the warranty therein, which covers Fairchild products.

Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/

FAN7346 • 1.0.0 19

FAN7346 — 4-Channel LED Current Balance Controller