Microsemi LX1686 Digital dimming ccfl controller ic Datasheet

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
T
H E
I
N F I N I T E
P
O W E R
I
O F
N N O VA T I O N
P
R E L I M I N A R Y
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.
D
A T A
S
H E E T
K E Y F E AT U R E S
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.
NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.
■ RangeMAXTM Wide Range Dimming (>100:1)
■ Synchronizable To Display Video Frequency
■ High Voltage Feedback Loop Directly
Controls Maximum Open Lamp And
Minimum Strike Voltages
■ Transformer Protected From Over-Heating
During Lamp Striking
■ Micro-Amp Sleep Mode
■ User-Programmable Fixed Frequency
Operation
■ Under-Voltage Lockout Feature With PowerUp Reset
■ Built-In Soft-Start Feature
■ Operates With 3.3V or 5V Power Supplies
■ 100mA Output Drive Capability
A P P L I C AT I O N S
■
■
■
■
Notebooks
Instrumentation Displays
Desktop Computer Monitors
Low Ambient Light Displays (used in
Aircraft, Automobiles, and Hand-held
Equipment)
BENEFITS
■ Extemely High Efficiency From 3.3V or 5V
Power Supplies
■ Lower Cost Than Conventional Buck / Royer
Inverter Topologies
■ Improved Lamp Strike Capability
■ Improved Over-Voltage Control
PRODUCT HIGHLIGHT
RANGEMAX
Power Used (Watts)
5
VS.
ANALOG DIMMING
Standard Analog
Dimming Inverter
4
3
LinFinity's
RangeMAX
2
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.
1
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
TSSOP
PW Plastic
24-pin
LX1686CPW
Note: All surface-mount packages are available in Tape & Reel.
Append the letter "T" to part number. (i.e. LX1686CPWT)
Copyright © 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
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
R E L I M I N A R Y
A B S O L U T E M A X I M U M R AT I N G S
D
A T A
S
H E E T
PACKAGE PIN OUTS
(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) .......................................................................... 150°C
Storage Temperature Range .............................................................. -65°C to 150°C
Lead Temperature (Soldering, 10 seconds) .................................................... 300°C
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.
AOUT
VSS_P
VSS
AFD_C
RAMP_C
RAMP_R
FVERT
PD_CR
VCO_C
BRT_POS
BRITE
DIG_DIM
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
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, 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.
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the recommended operating conditions of TA = 0 to 85°C, 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, CPDC= 0.047µF, RPD= 110kΩ.)
Parameter
Power Supply Voltage
Operating Current
Power Supply Voltage
Output Buffer Operating Current
UVLO Threshold
UVLO Hysteresis
Symbol
Test Conditions
VDD
IDD
VDD_P
I DD_P
VTH_UVLO
VH_UVLO
VDD = VDD_P
VDD = VDD_P = 5V
VDD = VDD_P
Volsns = VDD = VDD_P = 5V, CA = CB = 1000pF
Min.
LX1686
Typ.
3
Max.
160
V
mA
V
mA
V
mV
2.25
0.75
10
-2.55
2.65
2.25
0.75
1.5
1.65
100
200
300
45
1
V
V
Hz
µA
µA
V
V
V
V
KHz
KHz
mV
mV
µS
5
3
2
2.7
5.5
7
5.5
10
2.9
Units
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
2
FRAMP
FRAMP_HI
VTH_OLSNS
VH_OLSNS
TD_OLSNS
Tri_c = 0V
Tri_c = 3V
-2.3
2.3
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
-2.9
2.9
1.65
1.8
116
256
360
Copyright © 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
R E L I M I N A R Y
D
A T A
S
H E E T
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
Symbol
Test Conditions
Min.
LX1686
Typ.
Max.
Units
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
FR_VCO_I_SRC
FX_VCO
TD_AFD
VR_BRITE
VBRITE_FULL
Full-Darkness Brite Input Voltage
VBRITE_DARK
BRITE-to-ICOMP Propagation Delay
BRITE_POS Logic Threshold
DIG_DIM Logic Threshold
FR_FVERT
VTH_FVERT
RFVERT
VP_VCO
VV_VCO
40
Design Reference Only
Design Reference Only
VPD_CR = 3V, VDD = 3V
AFC_C = 0V, CVCO = 0.01µF
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
0
2.35
2.35
0.35
0.35
TD_BRITE
200
VDD/2
50
2.5
0.65
-5.8
250
1000
2.5
2.5
0.5
0.5
300
VDD/2
VDD/2
-5.2
VDD
2.65
2.65
0.65
0.65
Hz
V
kΩ
V
V
µA
Hz
ms
V
V
V
V
V
ns
V
V
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
DIG_DIM = VDD
VCOMP = 1.25V
VCOMP = 1.5V
VCOMP = 1.5V
Output Sink Current
ISK_OUTBUF
Output Source Current
IS_OUTBUF
AOUT, BOUT = VDD = 3V
AOUT, BOUT = 1V, VDD = 3V
AOUT, BOUT = 0V, VDD = 3V
AOUT, BOUT = 2V, VDD = 3V
VCOMP = VSNS
VCOMP = 0.5V, VDD = 3V
BRITE = 0.5 - 2.6V
ICOMP = 1.5V, VDD = 3V
ICOMP = 1.5V, VDD = 3V
CVCOMP = 1µF
VCOMP = 1.25V, VDD = 3V
VDD = 3V
ICOMP = 0.5 to 2.25V, VDD = 3V
BRITE = 1.25V, RAMP_C = 2V, VDD = 3V
0
10
20
0
1.12
0.8
70
-15
20
0
-10
-10
2.5
400
50
70
1.25
1.5
200
-40
60
110
120
VDD
1.38
10
700
-80
100
VDD
V
µmho
µA
µA
V
V
mA
µmho
µA
µA
V
ms
mV
ns
mV
ns
40
3
250
3
1100
10
500
10
45
35
-50
-40
80
55
-80
-55
mA
mA
mA
mA
1.02
V
µA
kΩ
V
V
V
mV
Output Buffer Block
25
20
-35
-20
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
Copyright © 2000
Rev. 0.4 1/00
VIR
IMAX_IR
RO_VBG
VEN3V
VEN5.5
VH_EN3
VH_EN5.5
0.98
Design Reference Only
Design Reference Only
VDD = 3V
VDD = 5.5V
1.5
2.7
50
10
1.9
3.2
0.45
350
2.4
3.6
3
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
R E L I M I N A R Y
D
A T A
S
H E E T
FUNCTIONAL PIN DESCRIPTION
4
Pin
Number
Pin
Designator
1
AOUT
Output driver A.
2
VSS_P
Power ground for output drivers only.
3
VSS
4
AFD_C
5
RAMP_C
Connects to external capacitor CRAMP for setting Direct Drive PWM operating frequency.
6
RAMP_R
Connects to external resistor RRAMP for setting Direct Drive PWM operating frequency.
7
FVERT
Vertical frequency reference digital input. Has internal pull down.
8
PD_CR
Phase Detector Filter. Part of phase lock loop. Connects to external capacitor and resistor network.
9
VCO_C
Connects to external capacitor CVCO.
10
BRT_POS
11
BRITE
12
DIG_DIM
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.
13
ENABLE
Chip Enable internal pullup. High enables the chip. Low disables.
14
I_R
Current Reference Resistor. External resistor to ground (Ri) determines internal capacitor CICOMP.
15
BRT
Current Error Amplifier non-inverting input.
16
VCOMP
17
VSNS
Voltage Error Amplifier inverting input.
18
ICOMP
Current Error Amplifier output. Connects to external frequency compensation capacitor CICOMP.
19
ISNS
20
OLSNS
21
TRI_C
Connects to external capacitor CTRI for setting strike frequency ramp slope.
22
VDD
VDD
23
VDD_P
Dedicated VDD for output buffers only.
24
BOUT
Output driver B.
Description
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.
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.
Voltage Error Amplifier output. Connects to external frequency compensation capacitor CVCOMP. Controls
soft-start timing.
Current Error Amplifier inverting input.
Open Lamp Sense Input.
Copyright © 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
R E L I M I N A R Y
D
S
A T A
H E E T
BLOCK DIAGRAM
C
B R T
IS N S
V S N S
P D _ C R
C
R
P D
C
P D
F V E R T
2 .5 V
A u to
F re q .
D e te c t
A F D _ C
C
V C O M P
IC O M P
V o lta g e
C o m p a ra to r
0 .2 5 -2 .2 5 V
C u rre n t
C o m p a ra to r
R A M P _ C
Q
E N A
P W R _ G D
2 .5 0 V
V D D _ S W
5 0 k
1 .5 V
V D D
O p e n L a m p
C o m p a ra to r
V D D
T r ia n g le
W a v e
G e n e ra to r
0 -3 V
Ig n ite
B
3 0 0 m V
2 5 5 m V
P W M
R a m p
G e n e ra to r
D im m in g C o n tr o l
R A M P _ C
C
R A M P
T R I_ C
R A M P _ R
R
R
R A M P 2
B O U T
V S S _ P
V D D
E N A B L E
I_ R
R i
B R T _ P O S
D IG _ D IM
A O U T
B ia s G e n e r a to r ,
U V L O , a n d V R EF
C L K
O U T
B R IT E
5 0 k
A
Q
R A M P _ D O U T
B u rs t
C o m p a ra to r
E N A
V D D _ P
IC O M P
0 .5 - 2 .5 V
V C O
O u tp u t
S te e r in g
L o g ic
V C O M P
IA M P
C u rre n t
E rro r A m p
V C O _ C
O u tp u t
D r iv e r s
P W M
C o n tr o lle r s
V A M P
1 .2 5 V
0 V
V C O
A F D
C
IC O M P
V o lta g e
E rro r
A m p
P h a s e
D e te c to r
P D C
C
V C O M P
C
V S S
O L S N S
T R I
R A M P 1
V D D
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 © 2000
Rev. 0.4 1/00
5
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