Fairchild (Now ON) FAN7318M, FAN7318M Schematic

FAN7318

LCD Backlight Inverter Drive IC

FAN7318 — LCD Backlight Inverter Drive IC

June 2011

Features

High-Efficiency Single-Stage Power Conversion

 

Wide Input Voltage Range: 6V to 30V



Backlight Lamp Ballast and Soft Dimming



Minimal External Components Required



Precision Voltage Reference Trimmed to 2%

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Half-Bridge Topology

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Soft-Start



PWM Control at Fixed Frequency

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Analog Dimming Function

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Burst Dimming Function

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Programmable Striking Frequency

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Open-Lamp Protection

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Open-Lamp Regulation

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Short-Lamp Protection

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CMP-High Protection

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FB-High Protection

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Thermal Shutdown

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20-Pin SOIC

Applications

LCD TV

 

LCD Monitor

Description

The FAN7318 is a LCD backlight inverter drive IC that controls P-N half-bridge topology.

The FAN7318 provides a low-cost solution and reduces external components by integrating proprietary wave rectifiers for open-lamp protection and regulation. The operating voltage range of the FAN7318 is wide, so an external regulator isn’t necessary to supply the voltage to the IC.

The FAN7318 provides various protections, such as open-lamp regulation, open-lamp protection, short-Lamp protection, CMP-high protection, and FB-high protection, to increase the system reliability. The FAN7318 provides burst dimming and analog dimming.

The FAN7318 is available in a 20-SOIC package.

Ordering Information

Part Number

FAN7318M

FAN7318MX Tape & Reel

Operating

Temperature

-25 to +85°C 20-Lead, Small Outline Integrated Circuit (SOIC)

Package Packing Method

Rail

Block Diagram

FAN7318 — LCD Backlight Inverter Drive IC

OLR1

OLR2

OLR3

OLR4

CT

CMP

ADIM

OLP1

OLP2

OLP3

OLP4

Min. &

Max.

Detector

/Fu ll Wave

Recifier

Open Lamp Regulation

max. 2V

min. 0.5V

Soft start by first

BCT waveform

Negative

Analog

Dimm ing

OLP max .

Min. & Max.

Detector

/Full or Half

Rectifier

Min.

0.3V

Max.

1.34V

2V

1.34V

2.2V

Gm = 350, Max. current 70µA

On @ stri king

Source current

1.3uA @ CMP>2.5V

Error. Amp. source current change

V

Error Amp.

ref

+

-

52µA burst sink current on

3.5V

Disable @ striking High_FB 8 pulses count @ normal Reset by BCT edge detect

Wave

OLP min .

0.7V/0.5V

Striking/normal

Short Lamp Protection

-

+

Over- Voltage Protection

Protection

+

-

High_FB

+

-

+

-

0µA

3.2µA

Error. Amp. source current change

Gm Amp.

+

Oscillator

-

+

0µA sink current @ striking

High CMP Protection

disable @ striking

+

3.5V

High FB Protection

disable @ striking

+

-

High_FB delay

-

+

High_CMP

Striking off

4 Output

Pulses

Counter

OLP

150µs Delay

High_FB

52µA burst sink current on

If ENA>2.5V, OLP & SLP disable. If ENA<2.1V, OLP & SLP enable.

Figure 1. Internal Block Diagram

Hys. 0.45V

50µA

On @ OVP, SLP

TSD 150oC

-

+

UVLO 5.5V

Voltage Reference

& Internal Bias

Soft start by first

BCT waveform

On @ High_CMP, OLP

+

-

3V/1V

@ striking /normal

Output Driver

Control

Logic

-

+

5V, max. 3mA

max. 2V

min. 0.5V

-

disable @ striking

+

2µA

TIMER

OUTA

OUTB

GND

VIN

1.35V

ENA

200k

REF

BCT

BDIM

Pin Configuration

FAN7318 — LCD Backlight Inverter Drive IC

OLP1

20 19 18 17 16 15 14 13

OLR1

OLP2

OLR2

OLP3

OLR3

OLP4

OLR4

VIN

OUTA

12 11

1 2 3 4 5 6 7 8

TIMER

CMP

ADIM

CT

Figure 2. Package Diagram

REF

BCT

BDIM

ENA

9 10

GND

OUTB

Pin Definitions

Pin # Name Description

1 TIMER This pin is for protection delay time setting.

2 CMP

3 ADIM This pin is the input for negative analog dimming.

4 CT

5 REF

6 BCT

7 BDIM

8 ENA This pin is for turning on/off the IC.

9 GND This pin is the ground.

10 OUTB This pin is NMOS gate-drive output.

11 OUTA This pin is PMOS gate-drive output.

12 VIN This pin is the supply voltage of the IC.

13 OLR4 This pin is for open-lamp regulation. Its functions are the same as the OLR1 pin.

14 OLP4

15 OLR3 This pin is for open-lamp regulation. Its functions are the same as the OLR1 pin.

16 OLP3

17 OLR2 This pin is for open-lamp regulation. Its functions are the same as the OLR1 pin.

18 OLP2

19 OLR1

20 OLP1

Error amplifier output. Typically, a compensation capacitor is connected to this pin from the ground.

This pin is for programming the switching frequency. Typically, a capacitor is connected to this pin from ground and a resistor is connected to this pin from the REF pin.

This pin is 5V reference output. Typically, resistors are connected to this pin from the CT pin and the BCT pin.

This pin is for programming the frequency of the burst dimming. Typically, a capacitor is connected to this pin from ground and a resistor is connected to this pin from the REF pin.

This pin is the input for negative burst dimming. The voltage range of 0.5 to 2V at this pin controls burst mode duty cycle from 0% to 100%.

This pin is for open-lamp protection and feedback control of lamp currents. Its functions are the same as the OLP1 pin.

This pin is for open-lamp regulation and short-lamp protection. It has the same functions as other OLR pins and is connected to the full-wave rectifier internally. When the maximum of rectified OLR inputs is between 1.34V and 2V, the error amplifier output current is limited to

3.2µA; and when the maximum of rectified OLR inputs reaches 2V, the error amplifier output current is 0A and its output voltage maintains constant. The maximum of rectified OLR inputs is inputted to the negative of another error amplifier for feedback control of lamp voltage. When the maximum of rectified OLR inputs is more than 2.2V, another error amplifier for OLR is operating and lamp voltage is regulated. In normal mode, if the maximum of rectified OLR inputs is higher than 1.35V or if the minimum of rectified OLR inputs is lower than 0.3V for a predetermined time by the TIMER pin capacitor and a internal current source 50µA, the IC shuts down to protect the system in over-voltage condition, short-lamp condition, respectively.

This pin is for open-lamp protection and feedback control of lamp currents. It has the same functions as other OLP pins and is connected to the half-wave rectifier and the full-wave rectifier internally. In striking mode, if the minimum of rectified OLP inputs is less than 0.7V for a predetermined time by the TIMER pin capacitor and an internal current source or, in normal mode, if the minimum of rectified OLP inputs is less than 0.5V for another predetermined time by the TIMER pin capacitor and another internal current source; the IC shuts down to protect the system in open-lamp condition. The maximum of rectified OLP inputs is inputted to the negative of the error amplifier for feedback control of lamp current.

FAN7318 — LCD Backlight Inverter Drive IC

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 6 30 V

TA Operating Temperature Range -25 +85

TJ Operating Junction Temperature +150

T

Storage Temperature Range -65 +150

STG

θJA Thermal Resistance Junction-Air

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.

(1,2)

90

°C °C °C

°C/W

FAN7318 — LCD Backlight Inverter Drive IC

Pin Breakdown Voltage

Pin # Name Value Unit

1 TIMER 7

2 CMP 7

3 ADIM 7

4 CT 7

5 REF 7

6 BCT 7

7 BDIM 7

8 ENA 7

9 GND

10 OUTB 10

11 OUTA 30

12 VIN 30

13 OLR4 ±7

14 OLP4 ±7

15 OLR3 ±7

16 OLP3 ±7

17 OLR2 ±7

18 OLP2 ±7

19 OLR1 ±7

20 OLP1 ±7

V

Electrical Characteristics

For typical values, TA=25°C, VIN=15V, and -25°C ≤ TA ≤ 85°C, unless otherwise specified. Specifications to -25°C ~ 85°C are guaranteed by design based on final characterization results.

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Under-Voltage Lockout Section (UVLO)

Vth Start Threshold Voltage Increase VIN 4.9 5.2 5.5 V

V

Start Threshold Voltage Hysteresis Decrease VIN 0.20 0.45 0.60 V

thhys

Ist Startup Current VIN=4.5V 10 70 100 µA

Iop Operating Supply Current VIN=15V, Not Switching 0.5 2.0 3.5 mA

ON/OFF Section

Von On-State Input Voltage 1.4 5.0 V

V

Off-State Input Voltage 0.7 V

off

Isb Standby Current ENA=0V 50 120 190 µA

R

Pull-Down Resistor ENA=2V 120 200 280 kΩ

ENA

Reference Section (Recommend 1µF X7R Capacitor)

V5 5V Regulation Voltage 4.9 5.0 5.1 V

FAN7318 — LCD Backlight Inverter Drive IC

V

5V Line Regulation

5line

V

5V Load Regulation

5load

Oscillator Section (Main)

f

Oscillation Frequency

osc

f

Oscillator Frequency in Striking Mode

str

I

ctdcs

I

ctdc

I

ctcs

V

cth

ctl

CT Discharge Current

Normal 770 870 970 µA

CT Charge Current Striking -15 -12 -9 µA

CT High Voltage 2 V

CT Low Voltage 0.45 V

Oscillator Section (Burst)

f

Burst Oscillation Frequency

oscb

I

BCT Discharge current 20 26 32 µA

bctdc

V

BCT High Voltage 2 V

bcth

V

BCT Low Voltage 0.5 V

bctl

6 ≤ VIN ≤ 30V

10µA ≤ I

T

A

≤ 3mA

5

=25°C, CT=220pF,

RT=100kΩ

4 50 mV

101.3 105.0 108.3 kHz

CT=220pF, RT=100kΩ 101 105 109

=25°C, CT=220pF,

T

A

RT=100kΩ

127.5 132.0 136.5 kHz

CT=20pF, RT=100kΩ 127 132 137

Striking 1.03 1.18 1.33 mA

=25°C, BCT=4.7nF,

T

A

BRT=1.4MΩ

BCT=4.7nF, BRT=1.4MΩ

324 333 345

Hz

320 333 346

FAN7318 — LCD Backlight Inverter Drive IC

Electrical Characteristics

(Continued)

For typical values, TA=25°C, VIN=15V, and -25°C ≤ TA ≤ 85°C, unless otherwise specified. Specifications to -25°C ~ 85°C are guaranteed by design based on final characterization results.

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Analog Dimming Section

ADIM=0V, T

ADIM=0V 1.212 1.310 1.408

AV

Reference Voltage

rexx

ADIM=0.5V 1.16

ADIM=1.0V 0.99

Error Amplifier Section

l

Output Sink Current OLP=2.5V, ADIM=2.5V 63 76 94 µA

sin

l

Output Source Current 1 OLP=0V, ADIM=0V -65 -50 -35 µA

sur1

l

Output Source Current 2 CMP=3V -1.7 -1.3 -0.9 µA

sur2

I

Burst CMP Sink Current BDIM=5V, BCT=0V 41 52 63 µA

bsin

I

OLP Input Current

olpi

I

OLP Output Current OLP=-2V -30 -20 -10 µA

olpo

OLP=2V 0 µA

OLP=0.3V 0.31 V

V

Rectifiers Output of OLP

lpfx

V

OLP Input Voltage Range

olpr

(3)

-4 4 V

OLP=1.5V 1.5 V

Open-Lamp Regulation Section

I

G

olr1

I

olr2

V

olr1

V

olr2

V

olr3

mOLR

I

ors

I

olri

I

olro

V

olrr

Error Amplifier Source Current for Open-Lamp Regulation

OLR Sweep 0 µA

Open-Lamp Regulation Voltage 1 OLR Sweep 1.24 1.34 1.44 V

Open-Lamp Regulation Voltage 2 Striking, OLR Sweep 1.88 1.98 2.08 V

Open-Lamp Regulation Voltage 3 2.1 2.2 2.3 V

OLR Error Amplifier Trans-conductance

OLR Error Amplifier Sink Current Normal, OLR=2.5V 50 70 90 µA

OLR Input Current OLR=2.5V 0 µA

OLR Output Current OLR=-2.5V -35 -25 -15 µA

OLR Input Voltage Range

(3)

-4 4 V

Striking, OLR=1.6V -4.0 -3.4 -2.9 µA

180 310 440 µmho

Note:

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

=25°C 1.225 1.310 1.402

A

V

FAN7318 — LCD Backlight Inverter Drive IC

Electrical Characteristics

(Continued)

For typical values, TA=25°C, VIN=15V, and -25°C ≤ TA ≤ 85°C, unless otherwise specified. Specifications to -25°C ~ 85°C are guaranteed by design based on final characterization results.

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Protection Section

V

Open-Lamp Protection Voltage 0

olp0

V

Open-Lamp Protection Voltage 1 Sweep OLP 0.42 0.49 0.56 V

olp1

V

CMP-High Protection Voltage Sweep CMP 3.4 3.5 3.6 V

cmpr

V

High-FB Protection Voltage

hfbp

V

Short-Lamp Protection Voltage Sweep TIMER 0.22 0.30 0.38 V

slp

V

Timer Threshold Voltage 1 Striking, Sweep TIMER 2.87 3.02 3.17 V

tmr1

V

Timer Threshold Voltage 2 Sweep TIMER 1.0 1.1 1.2 V

tmr2

I

Timer Current 1 OLP=0V 1.7 2.1 2.5 µA

tmr1

I

Timer Current 2 OLR=1.8V 40 50 60 µA

tmr2

TSD Thermal Shutdown

V

Over-Voltage Protection Voltage Sweep OLR 1.24 1.34 1.44 V

ovp

dcr

ENA2.3V OLP Disable/Enable Change Voltage

(4)

150 °C

Output Section

V

PMOS Gate High Voltage

pdhv

V

PMOS Gate Low Voltage VIN=15V VIN-9.5 VIN-8.5 VIN-7.0 V

phlv

V

NMOS Gate High Voltage VIN=15V 8.0 9.0 10.5 V

ndhv

V

NMOS Gate Low Voltage

ndlv

V

I

pdsur

I

pdsin

I

ndsur

I

ndsin

puv

nuv

PMOS Gate Voltage with UVLO Activated NMOS Gate Voltage with UVLO Activated

PMOS Gate Drive Source Current

PMOS Gate Drive Sink Current

NMOS Gate Drive Source Current

NMOS Gate Drive Sink Current

(4)

Maximum / Minimum Duty Cycle

DC

Minimum Duty Cycle

MIN

DC

Maximum Duty Cycle

MAX

(4)

f

(4)

f

Note:

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

(4)

Striking 0.65 0.70 0.75 V

(4)

3.4 3.5 3.6 V

2.1 2.3 2.5 V

(4)

VIN=15V VIN V

VIN=15V 0 V

=4.5V VIN-0.3 V

V

IN

V

=4.5V 0.3 V

IN

(4)

VIN=15V -300 mA

(4)

VIN=15V 400 mA

(4)

VIN=15V 300 mA

(4)

VIN=15V -400 mA

=100kHz 0 %

osc

=100kHz 45 49 %

osc

Fairchild (Now ON) FAN7318M, FAN7318M Schematic [ru]