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OB3309
Highly Integrated U Type CCFL Backlight Controller
Product Specification
GENERAL DESCRIPTION
OB3309 is a highly integrated and high
performance U-type Cold Cathode Fluorescent
Lamp (CCFL) controller optimized for LCD display
backlight application. Comprehensive protection
functions are integrated, thus it provides a cost
effective yet high reliability LCD backlight solution.
Operating in push pull configuration, OB3309
converts DC input voltage to the pure sinusoidal
voltage and current waveforms, to ignite and
operate CCFL lamps.
It provides a high degree of design flexibility by
offering great programmability for key parameters
which include operating frequency, striking
frequency, striking time, dimming polarity, burst
dimming frequency, soft-start time, and soft on/off
time for burst dimming.
Various dimming modes control and dimming
polarity programmability are offered. Both internal
burst and external low frequency PWM (LPWM)
dimming methods are available for a wide range of
dimming control. Analog dimming is also provided
through external DC input control to achieve wide
dimming range.
The highly integrated OB3309 provides complete
protection features covering output over voltage,
over output current protection, lamp fail safe
function, and IC under voltage lockout.
The OB3309 is available in SOP-16 Packages.
TYPICAL APPLICATION
FEATURES
High performance push pull topology
Optimized for U type CCFL solution
Adjustable dimming polarity
Adjustable striking frequency & time
Flexible Dimming mode Control:
| Analog dimming control
| Internal burst dimming control
| External burst (LPWM) dimming control
Adjustable minimum duty for internal burst
dimming
Adjustable minimum reference voltage for
analog dimming
0-2V DC voltage direct dimming control
without external circuits
Comprehensive Protection Coverage:
| Output over voltage protection (OVP)
| Output over current protection (OCP)
| Open lamp protection and short lamp
protection
| Arcing protection
APPLICATIONS
LCD Monitor
LCD TV
Flat panel display
VIN
DIM
ENA
+5V
GND
1 ENA
2 RI
3 RT
4 DRC
5 BF/DMOD
6 POL
7 VDD
8 GATE1
DIM 16
STIME 15
CMP 14
CS 13
PRT 12
VS 11
GND 10
GATE2 9
OB3309
PRT
VS
PRT
VS
VS
Figure1. OB3309 Typical Application Schematic
©On-Bright Electronics
Confidential
-1-
Preliminary Datasheet
OB_DOC_DS_330900
OB3309
Highly Integrated U Type CCFL Backlight Control
Electrical Characteristics
VDD=5V, ENA=5V, RT=36Kohm, RI=120Kohm, TA=25℃, if not otherwise noted.
Parameter
Symbol
Conditions
Min Typ Max Units
Current Consumption
Standby current
Operating supply current
Operating supply current
VDD UVLO
UVLO on
UVLO off
Istandby
IVDD
IVDD
ENA=0V
No loading, CMP=5V
Cload=2nF, CMP=5V
--
8 uA
- 4.5 6 mA
- 5.5 8 mA
3.6 V
4.4 V
Enable / Disable
ENA (Enable) threshold voltage
High Frequency Oscillator
Operating frequency
Striking frequency
Max. (overlap) duty cycle
ON
OFF
RENA
FOP
FSTK
Pull down resistor
2.0 V
0.8
100 Kohm
-
50 -
KHz
65 KHz
45 %
Low Frequency Oscillator for Burst Mode Dimming
Burst frequency
Max. burst duty
Min. burst duty 1 (set by DRC) 1
Min. burst duty 2 (set by DRC) 1
Min. burst duty 3 (set by DRC) 1
Min. burst duty 4 (set by DRC) 1
Analog Dimming Control
Min. Lamp Current Reference Voltage 1
(set by DRC) 1
Min. Lamp Current Reference Voltage 2
(set by DRC) 1
Max. Lamp Current Reference Voltage
DMAX
DMIN1
DMIN2
DMIN1
DMIN2
Vref_EA_MIN1
Vref_EA_MIN2
Vref_EA_MAX
CBF/DMOD=22nF
CBF/DMOD=22nF, DIM<0.2V
CBF/DMOD=22nF,
POL=0V,
VDRC=VRT, DIM>2V
CBF/DMOD=22nF,
POL=0V,
VDRC=92%VRT , VDRC <DIM<2V
CBF/DMOD=22nF,
POL=5V,
VDRC =0V, DIM<0.2V
CBF/DMOD=22nF,
POL=5V,
VDRC=9%VRT+0.2,DIM< VDRC
BF/DMOD=VDD, VDRC=0V
DIM>2V
BF/DMOD=VDD,
VDRC=25%VRT , DIM>1.28V
BF/DMOD=VDD, DIM<0.2V
,
-
-
-
-
-
-
-
-
-
External LPWM Dimming Control
External LPWM duty
External LPWM Logic input level
BF/DMOD=0V
high BF/DMOD=0V
low BF/DMOD=0V
0
2.0
200
100
0
9
0
9
0
0.5
1.25
-
-
-
-
-
-
-
-
-
-
100
0.8
Hz
%
%
%
%
%
V
V
V
%
V
V
©On-Bright Electronics
Confidential
-5-
Preliminary Datasheet
OB_DOC_DS_330900