Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
DESCRIPTION
The LX1686E Backlight Controller
IC provides all the control functions
needed to implement Microsemi’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 LX1686E 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 fr ame
rate to prevent interference from
optical beat frequencies.
Safety and reliability features include
a new dual feedback control 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 LX1686E
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.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
Protected by U.S. Patents 5,615,093; 5,923,129; 5,930,121; 6,198,234; Patents Pending
PRODUCT HIGHLIGHT
0
1
2
3
4
5
0 3045607590105
Light Output (Nits)
Power Used (Watts)
Standard Analog
Dimming Inverter
Microsemi's
RangeMAX
KEY FEATURES
RangeMAX™ Wide Range
Dimming (>100:1)
Synchronizable to Display Video
Frequency
High Voltage Feedback Loop
Directly Controls Maximum Open
Lamp
Micro-Amp Sleep Mode
User Programmable F ixed
Frequency Operation
Under-Voltage Lockout Feature
With Power-Up Reset
Built-In Soft-Start Feature
Operates With 3.3V or 5V power
Supplies
100mA Output Drive Capability
APPLICATIONS
Notebooks
Instrumentation Display
Desktop Computer Monitors
Low Ambient Light Displays
(used in Aircraft, Automobiles,
and Hand-Held Equipm ent)
BENEFITS
Extremely High Efficiency From
3.3V to 5V Power Supplies
Lower Cost Than Conventional
Buck / Royer Inverter Topologies
Improved Lamp Strike Capability
Improved Over-Voltage Control
PACKAGE ORDER INFO
PW Plastic TSSOP
24-PIN
TA (°C)
RoHS compliant / Pb-free
0 to 85 LX1686ECPW
-40 to 85 LX1686EIPW
Note: Available in Tape & Reel. Append the
letters “TR” to the part number. (i.e.
LX1686ECPW-TR)
L
LX
X1
16
68
86
6E
E
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.
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
ABSOLUTE MAXIMUM RATINGS
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
Maximum Operating Junction Temperature ..............................................................150°C
Storage Temperature...................................................................................-65°C to 150°C
RoHS / Pb-free Peak Package Solder Reflow Temperature
(40 second maximum exposure)....................................................................260°C (+0, -5)
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal
PACKAGE PIN OUT
VSS
AFD_C VDD
AOUT
VSS_P
RAMP_C
RAMP_R
FVERT
PD_CR
VCO_C
BRT_POS
BRITE
DIG_DIM
VDD_P
TRI_C
OLSNS
ISNS
ICOMP
VSNS
VCOMP
BRT
I_R
ENABLE
BOUT
2
3
4
5
6
7
8
9
10
11
12
1
23
22
21
20
19
18
17
16
15
14
13
24
PW PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin lead Finish
THERMAL DATA
PW PACKAGE
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 100°C/W
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.
P
PA
AC
CK
KA
AG
GE
E
D
DA
AT
TA
A
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
FUNCTIONAL PIN DESCRIPTION
PIN NAME DESCRIPTION
AOUT Output driver A, typical 10K pull down resistor to VSS_P.
VSS_P Power ground for output drivers only.
VSS Signal ground.
AFD_C Connects to an external capacitor, 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 VC O oscillate at 2x the FVERT frequency.
RAMP_C Connects to external capacito r CRAMP for setting Direct Drive PWM operating frequency.
RAMP_R Connects to external resistor RRAMP for setting Direct Drive PWM operating frequency.
FVERT Vertical frequency reference digital input. Has internal pull down.
PD_CR Phase Detector Filter. Part of phase lock loop. Connects to external capacitor and resistor network.
VCO_C Connects to external capacitor CVCO
BRT_POS Brightness control polarit y. Has internal pull up. Leave open or pull up to VDD for dimming brightness
proportional to BRITE voltage, connect to ground for brightness inversel y proportional to BRITE voltage.
BRITE Analog voltage input for brightness control.
DIG_DIM Digital Dimming Enable internal pull up. Leave open or pull up to VDD for oper ating in digital dimming mode.
Connect to ground for analog dimming mode.
ENABLE Chip Enable internal pull up. High enables the chip. Low disables.
I_R Current Reference Resistor. External resistor to ground (Ri) determines internal capacitor CICOMP.
BRT Current Error Amplifier non-inverting input
VCOMP Voltage Error Amplifier output. Connects to external frequenc y compensation capacitor CVCOMP. Controls soft-
start timing.
VSNS Voltag e Error Amplifier inverting input.
ICOMP Current Error Amplifier output. Connects to external frequency compensation capacitor CICOMP.
ISNS Current Error Amplifier inverting Input.
OLSNS Open Lamp Sense Input.
TRI_C Connects to external capacitor CTRI for setting strike Frequency ramp slope.
VDD VDD
VDD_P Dedicated VDD for output buffers only.
BOUT Output Driver B typical 10K pull down resistor to VSS_P.
P
PA
AC
CK
KA
AG
GE
E
D
DA
AT
TA
A
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature -0°C≤ TA≤ 85°C for the LX1686E
CPW and -40°C ≤ TA ≤ 85°C for the LX1686E IPW except where otherwise noted. Test conditions: VDD = VDD_P = 3.0 to 5.5V, Ri =
40kΩ, CVCO = 0.01µF, CAFD = 0.22µF, CTRI = 0.83µF, CRAMP = 208pF, RRAMP = 15kΩ, CPD = 0.22µF, CPDB = 0.047µF, RPD = 110kΩ
LX1686E
Parameter Symbol Test Conditions Min Typ Max
Units
Power Supply Voltage VDD VDD = VDD_P 3 5.5 V
Operating Current IDD VDD = VDD_P = 5V 5 10 mA
Power Supply Voltage VDD_P VDD = VDD_P 3 5.5 V
Output Buffer Operating Current IDD_P Volsns = VDD = VDD_P = 5V, CA = CB = 1000pF 2 10 mA
UVLO Threshold VTH_UVLO 2.7 2.9 V
UVLO Hysteresis VH_UVLO 160 mV
` DIRECT DRIVE RAMP BLOCK
Triangular Wave Generator Analog
Output Peak Voltage VP_TRI 2.25 V
Triangular Wave Generator Analog
Output Valley Voltage VV_TRI 0.75 V
Triangular Wave Generator Oscillation
Frequency F_TRI 10 Hz
Triangular Wave Generator Oscillation
Charge Current ICHG_TRI Tri_c = 0V -2.3 -2.55 -2.9 µA
Triangular Wave Generator Oscillation
Discharge Current IDISCHG_TRI Tri_c = 3V 2.3 2.65 2.9 µA
Ramp Generator Analog Output Peak
Voltage VP_RAMP 2.25 V
Ramp Generator Analog Output Valley
Voltage VV_RAMP 0.75 V
VDD = 3V 1.35 1.6 1.65 V
Ramp Frequency Change Threshold VTH_RAMP_R VDD = 5.5V 1.35 1.6 1.85 V
Ramp Generator Oscillation
Frequency – Nominal FRAMP 0 < VTRI_C < 1.35V 84 100 116 KHz
Ramp Generator Oscillation
Frequency – Maximum FRAMP_HI V
TRI_C = 2.25V 170 200 256 KHz
OLSNS Threshold Voltage VTH_OLSNS VDD = 3V 200 300 400 mV
OLSNS Hysteresis VH_OLSNS VDD = 3V 45 mV
OLSNS-to-ICOMP Propagation Delay TD_OLSNS GBD 1 µS
` DIGITAL DIMMER BLOCK
FVERT Input Frequency Capture
Range FR_FVERT 45 200 Hz
FVERT Logic Threshold VTH_FVERT Design Reference Only VDD/2 V
FVERT Input Resistance RFVERT Design Reference Only 50 kΩ
VCO Analog Output Peak Voltage VP_VCO 2.5 V
VCO Analog Output Valley Voltage VV_VCO 0.65 V
VCO Forced Source Current FR_VCO_I_SRC VPD_CR = 3V, VDD = 3V -6.4 -5.6 -5.1 µA
Forced VCO Oscillation Frequency FX_VCO AFC_C = 0V, CVCO = 0.01µF 250 Hz
Auto-Frequency Detection Response TD_AFD FVERT Frequency is 200Hz, VDD = 3V 1000 ms
BRITE Voltage Range VR_BRITE 0 VDD V
Full-Brightness Brite Input Voltage VBRITE_FULL V
BRT_POS = VDD or float; BRITE = 2.5V 2.25 2.5 2.65 V
VBRT_POS = 0V, BRITE = 0.5V 2.25 2.5 2.65 V
Full-Darkness Brite Input Voltage VBRITE_DARK VBRT_POS = VDD or float, BRITE = 0.5V 0.35 0.5 0.65 V
VBRT_POS = 0V, BRITE = 2.5V 0.35 0.5 0.65 V
E
EL
LE
EC
CT
TR
RI
IC
CA
AL
LS
S
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, the following specifications apply over the operating ambient temperature -0°C≤ TA≤ 85°C for the LX1686E
CPW and -40°C ≤ TA ≤ 85°C for the LX1686E IPW except where otherwise noted. Test conditions: VDD = VDD_P = 3.0 to 5.5V, Ri =
40kΩ, CVCO = 0.01µF, CAFD = 0.22µF, CTRI = 0.83µF, CRAMP = 208pF, RRAMP = 15kΩ, CPD = 0.22µF, CPDB = 0.047µF, RPD = 110kΩ
LX1686E
Parameter Symbol Test Conditions Min Typ Max
Units
` DIGITAL DIMMING BLOCK (CONTINUED)
BRITE-to-ICOMP Propagation Delay TD_BRITE 300 ns
BRITE_POS Logic Threshold VDD/2 V
DIG-DIM Logic Threshold VDD/2 V
` DIRECT DRIVE PWM BLOCK
ISNS Threshold Voltage Range VR_ISNS DIG_DIM = VDD 0 2.5 V
VAMP Transconductance GM_VAMP VCOMP = 1.25V 400 µmho
VAMP Output Source Current IS_VAMP VCOMP = 1.5V 10 50 110 µA
VAMP Output Sink Current ISK_VAMP VCOMP = 1.5V 15 70 120 µA
VAMP Output Voltage Range VR_VAMP 0 VDD V
VSNS Threshold Voltage VTH_VSNS VCOMP = VSNS 1.12 1.25 1.38 V
VCOMP Discharge Current ID_VCOMP VCOMP = 0.5V, VDD = 3V 0.8 1.5 10 mA
IAMP Transconductance GM_IAMP BRITE = 0.5 – 2.6V 70 200 700 µmho
IAMP Output Source Current IS_IAMP ICOMP = 1.5V, VDD = 3V -15 -40 -80 µA
IAMP Output Sink Current ISK_IAMP ICOMP = 1.5V, VDD = 3V 20 60 100 µA
IAMP Output Voltage Range VR_IAMP 0 VDD V
VCMP Input Offset Voltage VOS_VCMP VCOMP = 1.25V, VDD = 3V -10 3 10 mV
VCOMP-to-Output Propagation Delay TD_VCOMP VDD = 3V 250 500 ns
ICMP Input Offset Voltage VOS_ICMP ICOMP = 0.5 to 2.25V, VDD = 3V -10 3 10 mV
ICOMP-to-Output Propagation Delay TD_ICOMP BRITE = 1.25V, RAMP_C = 2V, VDD = 3V 1100 ns
` OUTPUT BUFFER BLOCK
AOUT, BOUT = 1V, VDD = 3V 20 200 mA
Output Sink Current ISK_OUTBUF AOUT, BOUT = VDD = 3V 25 300 mA
AOUT, BOUT = 0V, VDD = 3V -35 -300 mA
Output Source Current ISOUT_BUF AOUT, BOUT = 2V, VDD = 3V -20 -200 mA
` BIAS CONTROL BLOCK
Voltage at Pin I_R VIR .975 1.02 V
Pin I_R Maximum Source Current IMAX_IR Design Reference Only 50 µA
ENABLE Logic Threshold – 3V VEN3V VDD = 3V 0.8 1.4 2.0 V
ENABLE Logic Threshold – 5.5V VEN5.5 VDD = 5.5V 0.8 1.4 2.0 V
ENABLE Threshold Hysteresis – 3V VH_EN3 20 mV
ENABLE Threshold Hysteresis – 5.5V VH_EN5.5 300 mV
E
EL
LE
EC
CT
TR
RI
IC
CA
AL
LS
S
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
BLOCK DIAGRAM
CPD
RPD
CPDN
CAFD
CVCO
PD_CR
FVERT
AFD_C
VCO_C
BRITE
BRT_POS
DIG_DIM
Phase
Detector
Auto Freq.
Detect
VCO
Burst
Comparator
50k
50k
0-3V
ENA
Voltage
Error
Amp Voltage
Comparator
Current
Comparator
BRT ISNS VSNS
VCOMP ICOMP
Output
Steering
Logic VDD_P
AOUT
BOUT
VSS_P
CVCOMP CICOMP
A
B
CLK
OUT
RAMP_C RAMP_R TRI_C OLSNS
VSS
I_R
ENABLE
VDD
Triangle
Wave Gen.
Open Lamp
Comparator
Ignite
RAMP_DOUT
CRAMP RRAMP2 RRAMP1 CTRI
Ri
ENA
PWR_GD
2.50V
VDD_SW
VDD VDD
1.5V
300mV
255mV
VDD
Q
Q
VAMP
IAMP
VCOMP
ICOMP
2.5V
0V
1.25V
+
-
+
-
+
++
+
-
--
-
Dimming Control
PWM
Controllers
Output
Drivers
Bias Generator,
UVLO, and VREF
PWM R am p
Generator
0.5 - 2.5V
Current
Error A mp
B
BL
LO
OC
CK
K
D
DI
IA
AG
GR
RA
AM
M
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
PACKAGE DIMENSIONS
PW 24-Pin Thin Small Shrink Outline (TSSOP)
C
123
P
D
E
F
A
G
HL
BM
SEATING PLANE
MILLIMETERS INCHES
Dim MIN MAX MIN MAX
A 0.85 0.95 0.033 0.037
B 0.19 0.30 0.007 0.012
C 0.09 0.20 0.0035 0.008
D 7.70 7.90 0.303 0.311
E 4.30 4.50 0.169 0.177
F 0.65 BSC 0.025 BSC
G 0.05 0.15 0.002 0.005
H – 1.10 – .0433
L 0.50 0.75 0.020 0.030
M 0° 8° 0° 8°
P 6.25 6.55 0.246 0.256
*LC – 0.10 – 0.004
* Lead Coplanarity
Note:
1. Dimensions do not include mold flash or protrusions;
these shall not exceed 0.155mm(.006”) on any side.
Lead dimension shall not include solder coverage.
M
ME
EC
CH
HA
AN
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IC
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Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
Copyright © 2004
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX1686E
Di
g
ital Dimmin
g
CCFL Controller IC
P
RODUCTION
D
ATA SHEET
TM ®
NOTES
PRODUCTION DATA – Information contained in this document is proprietary to
Microsemi and is current as of publication date. This document may not be modified in
any way without the express written consent of Microsemi. Product processing does not
necessarily include testing of all parameters. Microsemi reserves the right to change the
configuration and performance of the product and to discontinue product at any time.
N
NO
OT
TE
ES
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