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RangeMAX
T
HE
TM
LX1686
D
ATA
D I G I TA L D I M M I N G C C F L C O N T R O L L E R I C
I
NFINITE
P
OWER
OF
I
N N O VAT I O N
P
RELIMINARY
S
HEET
DESCRIPTION The LX1686 Backlight Controller IC provides all the control functions needed to implement Linfinity's direct drive inverters used to operate cold cathode fluorescent lamps (CCFL's). This IC can be used to control single or multiple-lamp configurations. CCFL's are used for back or edge lighting of liquid crystal flat panel displays (LCD's) and typically find application in notebook computers, web browsers, automotive and industrial instrumentation, and entertainment systems. The LX1686 includes a PWM controlled lamp current burst circuit that can provide a >100:1 dimming range from a simple zero to 2.5V potentiometer input. The PWM dimming burst rate is easily synchronized to the LCD panel's frame rate to prevent interference from optical beat frequencies. Safety and reliability features include a new dual feedback contol loop that permits regulation of maximum lamp strike voltage as well as lamp current. Regulating maximum lamp voltage permits the designer to provide for ample worst case lamp strike voltage while at the same time conservatively limit maximum open circuit voltage. An innovative new strike voltage generation technique enables the module designer to optimize high voltage transformer design for maximum operating efficiency with no power dissipating overhead to guarantee strike capability. Direct drive topology is a non-resonant, oscillator-controlled PWM regulation method. The LX1686 allows a wide choice of fixed operating frequencies to match lamp current frequency to the lamp's most efficient operating point, and to minimize high frequency interference.
K E Y F E AT U R E S
s RangeMAXTM Wide Range Dimming (>100:1) s Synchronizable To Display Video Frequency s High Voltage Feedback Loop Directly Controls Maximum Open Lamp And Minimum Strike Voltages s Transformer Protected From Over-Heating During Lamp Striking s Micro-Amp Sleep Mode s User-Programmable Fixed Frequency Operation s Under-Voltage Lockout Feature With PowerUp Reset s Built-In Soft-Start Feature s Operates With 3.3V or 5V Power Supplies s 100mA Output Drive Capability
A P P L I C AT I O N S
s s s s Notebooks Instrumentation Displays Desktop Computer Monitors Low Ambient Light Displays (used in Aircraft, Automobiles, and Hand-held Equipment)
BENEFITS
s Extemely High Efficiency From 3.3V or 5V Power Supplies s Lower Cost Than Conventional Buck / Royer Inverter Topologies s Improved Lamp Strike Capability s Improved Over-Voltage Control
NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.
PRODUCT HIGHLIGHT
RANGEMAX
5
VS.
ANALOG DIMMING
Light emitted by a CCFL is proportional to the current flowing through it. There are two ways to control the current: by adjusting the amplitude of a continuous AC current; or, as with RangeMAX technology, by varying the amount of time a burst of full current is present. RangeMAX technology frees the backlight inverter module designer to operate in a lower brightness and lower power consumption mode than is possible with conventional amplitude control methods.
Power Used (Watts)
Standard Analog Dimming Inverter
4 3 2 1
LinFinity's RangeMAX
0
30
45
60
75
90
105
Light Output (Nits)
PA C K A G E O R D E R I N F O TA (C) 0 to 85
PW Plastic TSSOP 24-pin
LX1686CPW
Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. LX1686CPWT)
Copyright (c) 2000 Rev. 0.4 1/00
LINFINITY MICROELECTRONICS INC.
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570
1
PRODUCT DATABOOK 1996/1997
LX1686
D I G I TA L D I M M I N G C C F L C O N T R O L L E R I C
P
RELIMINARY
RangeMAX
D
ATA
TM
S
HEET PACKAGE PIN OUTS
AOUT VSS_P VSS AFD_C RAMP_C RAMP_R FVERT PD_CR VCO_C BRT_POS BRITE DIG_DIM
1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13
A B S O L U T E M A X I M U M R AT I N G S
(Note 1)
Supply Voltage (VDD, VDD_P) ......................................................................... 6.5V Digital Inputs .................................................................................. -0.3 to VDD+0.5V Analog Inputs .................................................................................. -0.3 to VDD+0.5V Digital Outputs ................................................................................ -0.3 to VDD+0.5V Analog Outputs ............................................................................... -0.3 to VDD+0.5V Operating Junction Temperature Plastic (DB, PW Packages) .......................................................................... 150C Storage Temperature Range .............................................................. -65C to 150C Lead Temperature (Soldering, 10 seconds) .................................................... 300C
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal.
BOUT VDD_P VDD TRI_C OLSNS ISNS ICOMP VSNS VCOMP BRT I_R ENABLE
PW PACKAGE (Top View)
T H E R M A L D ATA
PW PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, JA 100C/W
Junction Temperature Calculation: TJ = TA + (PD x JA). The JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow.
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the recommended operating conditions of TA = 0 to 85C, VDD=VDD_P= 3.0 to 5.5V) (Ri = 40k, CVCO= 0.01F, CAFD= 0.22F, CTRI= 0.83F, CRAMP= 208pF, RRAMP = 15k, CPD= 0.22F, CPDC= 0.047F, RPD= 110k.)
Parameter
Power Supply Voltage Operating Current Power Supply Voltage Output Buffer Operating Current UVLO Threshold UVLO Hysteresis
Symbol
VDD IDD VDD_P I DD_P VTH_UVLO VH_UVLO
Test Conditions
VDD = VDD_P VDD = VDD_P = 5V VDD = VDD_P Volsns = VDD = VDD_P = 5V, CA = CB = 1000pF
Min.
3
LX1686 Typ.
5
Max.
5.5 7 5.5 10 2.9
Units
V mA V mA V mV V V Hz A A V V V V KHz KHz mV mV S
3 2 2.7 160 2.25 0.75 10 -2.55 2.65 2.25 0.75 1.5 1.65 100 200 300 45 1
Direct Drive Ramp Block
Triangular Wave Generator Analog Output Peak Voltage VP_TRI Triangular Wave Generator Analog Output Valley Voltage VV_TRI Triangular Wave Generator Oscillation Frequency F_TRI Triangular Wave Generator Oscillation Charge Current ICHG_TRI Triangular Wave Generator Oscillation Discharge Current IDISCHG_TRI Ramp Generator Analog Output Peak Voltage VP_RAMP Ramp Generator Analog Output Valley Voltage VV_RAMP Ramp Frequency Change Threshold VTH_RAMP_R Ramp Generator Oscillation Frequency - Nominal Ramp Generator Oscillation Frequency - Maximum OLSNS Threshold Voltage OLSNS Hysteresis OLSNS-to-ICOMP Propagation Delay FRAMP FRAMP_HI VTH_OLSNS VH_OLSNS TD_OLSNS
Tri_c = 0V Tri_c = 3V
-2.3 2.3
-2.9 2.9
VDD = 3V VDD = 5.5V VTRI_C = 1.4V VTRI_C = 2.25V VDD = 3V VDD = 3V GBD
1.4 1.55 84 170 250
1.65 1.8 116 256 360
2
Copyright (c) 2000 Rev. 0.4 1/00
PRODUCT DATABOOK 1996/1997
RangeMAX
TM
LX1686
D I G I TA L D I M M I N G C C F L C O N T R O L L E R I C
P
RELIMINARY
D
ATA
S
HEET
E L E C T R I C A L C H A R A C T E R I S T I C S (continued) Parameter Digital Dimmer Block
FVERT Input Frequency Capture Range FVERT Logic Threshold FVERT Input Resistance VCO Analog Output Peak Voltage VCO Analog Output Valley Voltage VCO Forced Source Current Forced VCO Oscillation Frequency Auto-Frequency Detection Response BRITE Voltage Range Full-Brightness Brite Input Voltage Full-Darkness Brite Input Voltage BRITE-to-ICOMP Propagation Delay BRITE_POS Logic Threshold DIG_DIM Logic Threshold FR_FVERT VTH_FVERT RFVERT VP_VCO VV_VCO FR_VCO_I_SRC FX_VCO TD_AFD VR_BRITE VBRITE_FULL VBRITE_DARK TD_BRITE 40 Design Reference Only Design Reference Only VDD/2 50 2.5 0.65 -5.8 250 1000 2.5 2.5 0.5 0.5 300 VDD/2 VDD/2 200 Hz V k V V A Hz ms V V V V V ns V V V mho A A V V mA mho A A V ms mV ns mV ns mA mA mA mA V A k V V V mV
Symbol
Test Conditions
Min.
LX1686 Typ.
Max.
Units
VPD_CR = 3V, VDD = 3V AFC_C = 0V, CVCO = 0.01F FVERT Frequency is 200Hz, VDD = 3V VBRT_POS VBRT_POS VBRT_POS VBRT_POS = = = = VDD or float; BRITE = 2.5V 0V, BRITE = 0.5V VDD or float BRITE = 0.5V 0V, BRITE = 2.5V
-6.4
-5.2
0 2.35 2.35 0.35 0.35
VDD 2.65 2.65 0.65 0.65
Direct Drive PWM Block
ISNS Threshold Voltage Range VAMP Transconductance VAMP Output Source Current VAMP Output Sink Current VAMP Output Voltage Range VSNS Threshold Voltage VCOMP Discharge Current IAMP Transconductance IAMP Output Source Current IAMP Output Sink Current IAMP Output Voltage Range IAMP Input Offset Voltage VCMP Input Offset Voltage VCOMP-to-Output Propagation Delay ICMP Input Offset Voltage ICOMP-to-Output Propagation Delay VR_ISNS GM_VAMP IS_VAMP ISK_VAMP VR_VAMP VTH_VSNS ID_VCOMP GM_IAMP IS_IAMP ISK_IAMP VR_IAMP TSS VOS_VCMP TD_VCOMP VOS_ICMP TD_ICOMP ISK_OUTBUF IS_OUTBUF DIG_DIM = VDD VCOMP = 1.25V VCOMP = 1.5V VCOMP = 1.5V VCOMP = VSNS VCOMP = 0.5V, VDD = 3V BRITE = 0.5 - 2.6V ICOMP = 1.5V, VDD = 3V ICOMP = 1.5V, VDD = 3V CVCOMP = 1F VCOMP = 1.25V, VDD = 3V VDD = 3V ICOMP = 0.5 to 2.25V, VDD = 3V BRITE = 1.25V, RAMP_C = 2V, VDD = 3V AOUT, BOUT = VDD = 3V AOUT, BOUT = 1V, VDD = 3V AOUT, BOUT = 0V, VDD = 3V AOUT, BOUT = 2V, VDD = 3V 0 10 20 0 1.12 0.8 70 -15 20 0 -10 -10 400 50 70 1.25 1.5 200 -40 60 40 3 250 3 1100 45 35 -50 -40 2.5 110 120 VDD 1.38 10 700 -80 100 VDD 10 500 10
Output Buffer Block
Output Sink Current Output Source Current 25 20 -35 -20 0.98 Design Reference Only Design Reference Only VDD = 3V VDD = 5.5V 50 10 1.9 3.2 0.45 350 80 55 -80 -55 1.02
Bias Control Block
Voltage at Pin I_R Pin I_R Maximum Source Current VBG Output Resistance ENABLE Logic Threshold - 3V ENABLE Logic Threshold - 5.5V ENABLE Threshold Hysteresis - 3V ENABLE Threshold Hysteresis - 5.5V VIR IMAX_IR RO_VBG VEN3V VEN5.5 VH_EN3 VH_EN5.5
1.5 2.7
2.4 3.6
Copyright (c) 2000 Rev. 0.4 1/00
3
PRODUCT DATABOOK 1996/1997
LX1686
D I G I TA L D I M M I N G C C F L C O N T R O L L E R I C
P
Pin Number
1 2 3 4 RELIMINARY
RangeMAX
D
ATA
TM
S
HEET
FUNCTIONAL PIN DESCRIPTION
Pin Designator
AOUT VSS_P VSS AFD_C
Description
Output driver A. Power ground for output drivers only. Signal ground. Connects to an external cap, CAFD. Forcing to ground or VDD will make the VCO oscillate at approximately 50% of the maximum VCO frequency. Forcing to VDD/2 will make the VCO oscillate at 2x the FVERT frequency. Connects to external capacitor CRAMP for setting Direct Drive PWM operating frequency. Connects to external resistor RRAMP for setting Direct Drive PWM operating frequency. Vertical frequency reference digital input. Has internal pull down. Phase Detector Filter. Part of phase lock loop. Connects to external capacitor and resistor network. Connects to external capacitor CVCO. Brightness control polarity. Has internal pullup. Leave open or pull up to VDD for dimming brightness proportional to BRITE voltage, connec to ground for brightness inversely proportional to BRITE voltage. Analog voltage input for brightness control. Digital Dimming Enable internal pullup. Leave open or pull up to VDD for operating in digital dimming mode. Connect to ground for analog dimming mode. Chip Enable internal pullup. High enables the chip. Low disables. Current Reference Resistor. External resistor to ground (Ri) determines internal capacitor CICOMP. Current Error Amplifier non-inverting input. Voltage Error Amplifier output. Connects to external frequency compensation capacitor CVCOMP. Controls soft-start timing. Voltage Error Amplifier inverting input. Current Error Amplifier output. Connects to external frequency compensation capacitor CICOMP. Current Error Amplifier inverting input. Open Lamp Sense Input. Connects to external capacitor CTRI for setting strike frequency ramp slope. VDD Dedicated VDD for output buffers only. Output driver B.
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
RAMP_C RAMP_R FVERT PD_CR VCO_C BRT_POS BRITE DIG_DIM ENABLE I_R BRT VCOMP VSNS ICOMP ISNS OLSNS TRI_C VDD VDD_P BOUT
4
Copyright (c) 2000 Rev. 0.4 1/00
PRODUCT DATABOOK 1996/1997
RangeMAX
TM
LX1686
D I G I TA L D I M M I N G C C F L C O N T R O L L E R I C
P
RELIMINARY
D
ATA
S
HEET
BLOCK DIAGRAM
C
VCOMP
C
IC O M P
BRT PD _CR
C R
PDC PD
IS N S
VSNS
V o lta g e E rro r Amp VAMP IA M P
VCOMP
IC O M P
PW M C o n tr o lle r s
V o lta g e C o m p a ra to r VCOMP Q IC O M P C u rre n t C o m p a ra to r Q RAM P_DO UT O u tp u t S te e r in g L o g ic A
O u tp u t D r iv e r s
VD D_P AOUT
C
PD
P hase D e te c to r 2 .5 V VCO 0V 1 .2 5 V
FVERT AFD_C
C
AFD
A u to F re q . D e te c t
VC O _C
C
VCO
C u rre n t E rro r A m p 0 .5 - 2 .5 V B u rs t C o m p a ra to r
0 .2 5 -2 .2 5 V
B
BOUT VSS_P
RAM P_C
B R IT E
50k 50k
CLK OUT ENA PW R _G D 2 .5 0 V VD D _SW 300m V 255m V
B ia s G e n e r a to r , U V L O , a n d V REF
VDD
ENA 1 .5 V
VDD
VDD T r ia n g le W ave G e n e ra to r
O pen Lam p C o m p a ra to r Ig n ite
ENABLE I_ R
Ri
0 -3 V
BRT_PO S D IG _ D IM
D im m in g C o n tr o l
RAM P_C
C
RAMP
PW M Ram p G e n e ra to r
RAM P_R
R
RAMP2
VSS
T R I_ C
R C
RAMP1 TRI
OLSNS
VDD
FIGURE 1 -- LX1686 Block Diagram
RangeMAX and is a trademark of Linfinity Microelectronics Inc.
PRELIMINARY DATA - Information contained in this document is pre-production data, and is proprietary to LinFinity. It may not modified in any way without the express written consent of LinFinity. Product referred to herein is offered in sample form only, and Linfinity reserves the right to change or discontinue this proposed product at any time.
Copyright (c) 2000 Rev. 0.4 1/00
5

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